Technical Training Product

Information.
Advanced Diesel with
BluePerformance.
 BMW Service
The information contained in the Product Information and the Workbook form an integral part of
the training literature of BMW Technical Training.

Refer to the latest relevant BMW Service information for any changes/supplements to the
Technical Data.

Information status: June 2008

Contact: conceptinfo@bmw.de

© 2008 BMW AG
München, Germany
Reprints of this publication or its parts require the written approval of
BMW AG, München
VH-23, International Technical Training
Product Information. Advanced
Diesel.

Diesel engine for North America

Selective Catalytic Reduction (SCR)

Low pressure exhaust gas recirculation

(LP EGR)
Notes on this Product Information
Symbols used
The following symbols are used in this Product Information to improve
understanding and to highlight important information:

3 contains important safety information as well as information that is

necessary to ensure smooth system operation and must be adhered to.

1 identifies the end of a note.

Information status and national variants

BMW vehicles conform to the highest safety and quality standards.
Changes in terms of environmental protection, customer benefits and
design render necessary continuous development of systems and
components. Consequently, there may be discrepancies between this
Product Information and the vehicles available in the training course.
This documentation describes left-hand drive vehicles. In right-hand
drive vehicles, the arrangement of some controls or components may
differ from the illustrations in this Product Information. Further differences
may arise as the result of the equipment variants used in specific markets
or countries.

Additional sources of information

Further information on the individual topics can be found in the following:
- Owner's Handbook
- Integrated Service Technical Application.

Contents.
Advanced Diesel.
 1
Objectives
Product information and working reference for
practical applications. 1

Models 3
Engine variants 3

Introduction 7

System components 23
Engine mechanical system 23
Air intake and exhaust system 25
Cooling system 38
Fuel preparation system 41
Overview of fuel supply system 43
Functions of the fuel supply system 47
Components of the fuel supply system 51
Overview of selective catalytic reduction Functions 60
of selective catalytic reduction
system 72
Components of the selective catalytic
reduction system 95
Engine electrical system 110
Automatic transmission 119
 6
Objectives.
Advanced Diesel.

Product information and working reference for practical

applications. This Product Information is structured as a
working reference and complements the
This Product Information provides information subject material of the BMW Aftersales
on the design and function of the M57D30T2 Training seminar. The Product Information is
US engine. also suitable for self-study.

1
 As a preparation for the technical training
program, this Product Information provides an
insight into the diesel engine for the US
market. In conjunction with practical exercises
carried out in the training course, its aim is to
enable course participants to carry out
servicing work on the M57D30T2 US engine.
Technical and practical background
knowledgeofthecurrentBMWdieselengines
willsimplifyyourunderstandingofthesystems
described here and their functions.

2
6

3
 7
Models.
Advanced Diesel.

Engine variants

200/265 580
335d E90 M57D30T2 2993 90/84 11/08
4200 1750

1
 200/265 580
X5 xDrive35d E70 M57D30T2 2993 90/84 11/08
4200 1750
Models with the M57D30T2 US engine at the
time of market launch in Autumn 2008.

1 - BMW 335d 2 - BMW X5 xDrive35d

2
7

History of the M57 engine its introduction and many improvements

have been made during this period. In
The M57 engine is by far one of the most
particular the re-engineering that took place
successful engines at BMW. It is fitted in
in 2002 and again in 2005 ensure that the
numerous models right across the vehicle
M57 engine is still state-of-the-art.
range. It plays the part of the extremely
powerfultop-of-the-rangeengine,forexample The following table shows an overview of the
in the 3 Series just as effectively as the individual models equipped with the M57
wellbalanced entry class engine in the 7 engine.
Series. 10 years have already passed since

M57D30O0 530d E39 2926 135/184 390 DDE4.0 9/98 3/00

M57D30O0 730d E38 2926 135/184 410 DDE4.1 9/98 3/00

M57D30O0 330d E46 2926 135/184 390 DDE4.0 9/99 3/03

M57D25O0 525d E39 2497 120/163 350 DDE4.0 3/00 2/04

M57D30O0 530d E39 2926 142/193 390 DDE4.0 3/00 5/04

M57D30O0 730d E38 2926 142/193 430 DDE4.1 3/00 7/01

M57D30O0 X5 3.0d E53 2926 135/184 410 DDE4.0 4/01 9/03

3
 M57D30O1 730d E65 2993 160/218 500 DDE506 9/02 3/05

M57D30O1 330d E46 2993 150/204 410 DDE506 3/03 9/06

M57D30O1 530d E60 2993 160/218 500 DDE508 3/03 4/04

M57D30O1 X3 3.0d E83 2993 150/204 410 DDE506 9/03 9/05

M57D30O1 X5 3.0d E53 2993 160/218 500 DDE506 9/03 9/06

M57D25O1 525d E60 2497 130/177 400 DDE509 4/04 3/07

M57D25O1 525d E61 2497 130/177 400 DDE509 4/04 3/07

M57D30O1 530d E60 2993 160/218 500 DDE509 4/04 9/05

M57D30O1 530d E61 2993 160/218 500 DDE509 4/04 9/05

M57D30T1 535d E90 2993 200/272 560 DDE606 9/04 3/07

M57D30T1 535d E61 2993 200/272 560 DDE606 9/04 3/07

M57D30O2 730d E65 2993 170/231 520 DDE626 3/05 9/08

M57D30O2 330d E90 2993 170/231 500 DDE626 9/05 9/08

M57D30O2 330d E91 2993 170/231 500 DDE626 9/05 9/08

M57D30O2 530d E61 2993 170/231 500 DDE626 9/05 in production

M57D30O2 530d E61 2993 170/231 500 DDE626 9/05 in production

M57D30O2 730Ld E66 2993 170/231 520 DDE626 9/05 9/08

M57D30O2 X3 3.0d E53 2993 160/218 500 DDE626 9/05 in production

M57D30U2 325d E90 2497 145/197 400 DDE606 9/06 in production

4
M57D30U2 325d E91 2497 145/197 400 DDE606 9/06 in production

M57D30O2 330d E92 2993 170/231 500 DDE626 9/06 in production

M57D30T2 335d E90 2993 210/286 580 DDE626 9/06 in production

M57D30T2 335d E91 2993 210/286 580 DDE626 9/06 in production

M57D30T2 335d E92 2993 210/286 580 DDE626 9/06 in production

M57D30T2 X3 3.0sd E83 2993 210/286 580 DDE626 9/06 in production

M57D30U2 325d E92 2497 145/197 400 DDE606 3/07 in production

M57D30U2 525d E60 2497 145/197 400 DDE606 3/07 in production

M57D30U2 525d E61 2497 145/197 400 DDE606 3/07 in production

M57D30O2 330d E93 2993 170/231 500 DDE626 3/07 in production

M57D30O2 X5 3.0d E70 2993 173/235 520 DDE626 3/07 in production

M57D30T2 535d E60 2993 210/286 580 DDE626 3/07 in production

M57D30T2 535d E61 2993 210/286 580 DDE626 3/07 in production

M57D30U2 325d E93 2497 145/197 400 DDE606 9/07 in production

M57D30T2 635d E63 2993 210/286 580 DDE626 9/07 in production

M57D30T2 635d E64 2993 210/286 580 DDE626 9/07 in production

M57D30T2 X5 3.0sd E70 2993 210/286 580 DDE626 9/07 in production

M57D30O2 X6 E71 2993 173/235 520 DDE626 5/08 in production

xDrive30d
M57D30T2 X6 E71 2993 210/286 580 DDE626 5/08 in production
xDrive35d

7
 8
Introduction.
Advanced Diesel.

A diesel engine for North America

Impressive power and performance as well synonym for extremely low CO2 emissions
as exemplary efficiency have contributed to not surprising when considering its
making BMW diesel engines an attractive as extremely low fuel consumption.
well as future-oriented drive technology. This EfficientDynamics is not solely an instrument
technology is now being made available to for reducing fuel consumption but rather it is
drivers in North America. designed as an intelligent entity with
BMW is introducing this diesel technology to increased dynamics. Not
the USA and Canada under the name "BMW withoutgoodreasontheM57D30T2engineis
Advanced Diesel". The introduction is an referred to as the world's most agile diesel
integral part of the EfficientDynamics engine.
development strategy, which has become a

History view of the improved dynamics and acoustics the

decision was made to introduce the diesel engine in
In 1892, Rudolf Diesel applied for a patent for his first
series production vehicles at BMW.
self-igniting combustion engine. Initially, this large,
slow-running engine was intended for stationary
operation only. The intricate engine structure and
complicated injection system meant production costs
were high. The first simple diesel engines were not
particularly comfortable and powerful-revving
machines. It was not possible to mistake the distinctive
sound of the harsh combustion process in the diesel
engine when cold (diesel
knock).Comparedtothesparkignitionengine, it offered
a poorer power/weight ratio, acceleration
characteristics and lower specific output.
"Miniaturization" could be realized only by improving
materials and the manufacturing process during the
course of commercial vehicle production. Although the
first diesel vehicle was presented as early as 1936, it
was not before the 1970s that the diesel engine
became accepted as a viable drive source. The
breakthrough came in the 1980s when the diesel
engine was finally refined enough to be a real
alternative to the spark ignition engine. At this time, in

6
 8
1 - Rudolf Diesel and his engine
therefore be built on the same
1983 production facilities.
The M21D24 engine introduced for At that time, the performance with a top speed of 180

the first time in the E28 as the km/h and acceleration from 0 to 100 km/h in 13.5
524td featured an exhaust seconds set new standards in the dynamics of diesel
turbocharger and had a motor vehicles. The 524td was therefore given the
displacement of 2.4 litres. It was nickname "Sport diesel".
derived from the M20 6cylinder ThiswasthefirstdieselengineatBMWand,at the same
petrol engine and developed 85
time, the last for a long time in the US market.
kW/ 115 bhp. Both engines could
2 - BMW 524td with M21 engine
As the world's first carmaker to do so, BMW
introduced the electronic engine management
1985 system, the so-called Digital Diesel Electronics
The M21 was also built as a (DDE). Faster and more exact than a mechanical
naturallyaspirated diesel engine as control system, the electronics effectively controls:
from September 1985, making it • Exhaust emission characteristics
possible to offer a costeffective
• Fuel consumption characteristics
"entry-level engine". This engine
made a name for itself in the 324d • Noise emission
(E30) as the smoothestrunningauto- • Engine running refinement.
ignitionengineonthe market.
1991
1987
1991 saw the debut of the newly developed M51D25
engine which, with intercooling and an output of 105
 8
kW/143 bhp was the most powerful diesel engine in
its class throughout the world. It replaced the M21
engine and was fitted with a crankcase based on a
completely new design.
The engine was offered in the output
variants 115 bhp and 143 bhp.
Exhaust emission and full load smoke
were reduced by a V-shaped main
combustion chamber in the piston.

3 - BMW 525tds with M51 engine

1994 hollow-cast camshaft mounted in 5 bearings

as well as a cylinder head cover the isolated
The M41 engine was the first 4-cylinder diesel structure-borne noise.
enginetobeusedatBMW.Itwasderivedfrom the M51D25 engine and shared 56 % of its This
engine was fitted in various models of the components. New features included the E36 series.

8
 8
1998 With 100 kW developed from 2 litre displacement, a
performance level was achieved which up until then
In 1998 BMW built the most
was the reserve only of petrol engines. This
powerful 4cylinder diesel engine -
corresponds to a specific output of 50 kW or 68 bhp.
the M47 with direct fuel injection.
4 - BMW 320d with M47 engine

Motor sport provided the best historic success on the Nürburg

proof of the efficiency and Ring.
reliability of the new diesel With the 320d, a diesel engine won a 24 hour race for
technology. BMW celebrated a the first time in motor sports history in 1998. This
victory came not only due to the fact that it needed

5 - BMW 320d touring car with M47 engine

 8
fewer pit stops for refuelling but also because the world's most powerful passenger vehicle diesel engine
BMW drove the fastest lap times. with common rail fuel injection and 2 exhaust
1999 turbochargers.
The engine is fitted with a crankcase
The first V8 diesel engine, the M67D40 engine,
made from high-strength cast iron
with 4 litre displacement was presented in the E38
with vermicular graphite (GGV), an
which developed an output of 175 kW. BMW
aluminium cylinder head and a two-
proved its technical authority with the, at that time,
piece oil sump.

6 - BMW 740d with M67 engine

2001
The M47TU with the second generation common rail
injection system and DDE5 boosted the power output
to 110 kW/150 bhp.
The M57D30 engine is a further development of the
M51D25 engine. It has a cast iron casing fitted with a
light alloy cylinder head with 4-valve technology. The
M57 engine is theworld'sfirst6-cylinderin-line
dieselengine in a passenger vehicle that is equipped
with future-oriented common rail injection technology.
This new, highly complex electronically
controlled fuel injection system
perfectly satisfies the demands for
high and constant injection pressure
over the entire injection period. The
engine offers substantially lower fuel
consumption compared to swirl-
chamber engines, superior
performance and smooth engine
operation under extreme conditions.

10
 8

7 - BMW 530d with M57 engine

535d develops 40 kW/54 bhp more
than at the same displacement (3.0
2004 litres) in the 530d.
The M57TU TOP engine with 2- The power output is 200 kW/272 bhp. The maximum
stage turbocharging is introduced torque of 560 Nm is reached at 2000 rpm. With this
as the most powerful diesel engine extraordinary engine, Luc Alphand won not only the
(E60 and E61). One diesel classification of the Paris-Dakar Rally, but also
smallandonelargeturbochargerisuse came fourth in the overall rankings.

8 - BMW X5 3.0d with M57TU TOP engine

dinthe 2-stage turbocharging 2005
system. The diesel engine in the
 8
The M57TU2 engine is fitted in the E65. In addition 1600 bar

to the increase in output and torque, it boasts the • Compliance with the exhaust
following technical features: emissionregulation EURO 4 and diesel
• Reduced weight through particulate filter as standard
aluminiumcrankcase • Optimized electric boost pressure
actuatorfor the turbocharger with variable
• 3rd generation common rail system
withpiezo-injector and a fuel rail pressure of turbine geometry.
9 - BMW 730d with M57TU2 engine

2005
The M67 engine in the E65 was comprehensively
reengineered in the same year. The aim was to
achieve a distinct boost in dynamics by increasing
power output and reducing weight. In the case of the
M67 specifically this aim is reflected in an increase in
power output of 16 % while simultaneously reducing
the engine weight by 14 % - and achieved without
increasing fuel consumption.
This was mainly achieved through a
new, lightweight aluminium crankcase
and by increasing the displacement to
4.4 litres.

12
 8

10 - BMW 745d with M67TU engine

the permissible limits for a range of pollutants have
been further and further reduced. In the meantime, all
2006 industrial nations have introduced exhaust emission
In 2006, the M57TU TOP engine legislation that defines the emission limits for petrol
was reengineered and equipped and diesel engines as well as the test methods.
with the same technical details as Essentially, the following exhaust emission legislation
the M57TU2, such as an aluminium applies:
crankcase and piezo-fuel injectors.
• CARB legislation (California Air ResourcesBoard),
This engine was given the
California
designation M57D30T2. It was
introduced simultaneously into the 3 • EPA legislation (Environmental ProtectionAgency),
Series as the 335d and in the X3 as USA
the 3.0sd. This re-engineering • EU legislation (European Union) andcorresponding
resulted in further-improved power ECE regulations (UN Economic Commission for
characteristics, enhanced smooth Europe), Europe
operation and a significant reduction
in fuel consumption. This engine • Japan legislation.
forms the basis for re-introducing This legislation has lead to the development of
diesel technology into the USA after different requirements with regard to the limitation of
more than 20 years. various components in the exhaust gas. Essentially,
the following exhaust gas constituents are evaluated:
Legislation
Since the first exhaust emission legislation for petrol • Carbon monoxide (CO)
engines came into force in the mid1960s in California,

11 - X3 3.0sd with M57TU2 TOP engine

 8

• Nitrogen oxides (NOx)

• Hydrocarbons (HC)
• Particulates (PM)
It can generally be said that
traditionally more emphasis is
placed on low nitrogen oxide
emissions in US legislation while in
Europe the focus tends to be more
on carbon monoxide.
The following graphic compares the
standard applicable to BMW diesel
vehicles with the current standards
in Europe. A direct comparison,
however, is not possible as •
different measuring cycles are used
and
• different values are measured forhydrocarbons.

14
 8
12 - Comparison of exhaust
emission legislation
Diesel engines
generally have
higher nitrogen
oxide emission
levels than petrol
engines as diesel
engines are
normally
operated with an
air surplus.
For this reason,
the challenge of
achieving
approval in all 50
states of the
USA had to be
met with a series
of new
technological
developments.
The following
table provides an
Standard Valid from CO NMHC** PM overview of the
NOx HC + NOx* special features
[mg/km] [mg/km] [mg/km] [mg/km] [mg/km]
of the
EURO 4 01.01.2005 500 250 300 - 25 M57D30T2 US
engine. They are
EURO 5 01.09.2009 500 180 230 - 5 divided into
EURO 6 01.09.2014 500 80 170 - 5 various
categories.
LEV II MY 2005 2110 31 - 47 6
• New
* In Europe, the sum of nitrogen oxide and hydrocarbons is evaluated, i.e. the higher the HC development
emissions, the lower the NOx must be and vice versa. signifies a
** In the USA, only the methane-free hydrocarbons are evaluated, i.e. all hydrocarbons with technologythat
has not
previously been
Overview of innovations, modifications and special features used on BMW
no methane engines.

Although the European and US

standards cannot be compared 1:1
it is clear that requirements relating
to nitrogen oxide emissions are
considerably more demanding.
 8
• Modificationsignifiesacomponentthatwasspecificall Europe version as well as
y designed for the fundamentalvehiclesystemsspecifictodi
M57D30T2 US engine but does not esel engines.

Component Remarks
Engine mechanical system 7 Very few modifications have been made to
the basic engine. The modifications that
have been made focus mainly on ensuring
smooth engine operation.
A significant feature, however, is the OBD
monitoring of the crankcase breather.
Air intake and exhaust 7 The most extensive changes were made to
system the air intake and exhaust system. For
instance, low pressure exhaust gas
recirculation (low pressure EGR) is used for
the first time at BMW on the E70.
In addition to other minor adaptations, there
are substantial differences in the sensor and
actuator systems.
Cooling system 7 In principle, the cooling system corresponds
to that of the Europe versions, however, it
has been adapted to hot climate
requirements.
Fuel preparation system 7 The functional principle of the fuel
preparation system does not differ from
that of the Europe version, however,
individual components have been adapted
to the different fuel specification.
represent a technical innovation.
• Adopted describes a component that hasalready
been used in other BMW engines.
This Product Information describes
only the main modifications to the
M57D30T2 engine compared to the

16
 8

Component Remarks
Fuel supply system 7 The fuel supply system is vehicle-specific
and corresponds to the Europe version.
Thereare,however,significantdifferencesto
petrol engine vehicles.
SCR system 7 The SCR system is used for the first time at
(Selective Catalytic BMW. Nitrogen oxide emissions are
Reduction) drastically reduced by the use of a reducing
agentthatisinjectedintotheexhaustsystem
upstream of a special SCR catalytic
converter. Since the reducing agent is
carried in the vehicle, a supply facility, made
up of two reservoirs, is part of this system.
Engine electrical system 7 The engine is equipped with the new DDE7
(digitaldieselelectronics)controlunitthatwill
beusedinthenextgenerationdieselengines
(N47, N57).
The preheater system also corresponds to
the N47/N57 engines.
Automatic transmission 7 The automatic transmission corresponds to
that in the ECE variant of the X5 xDrive35d.
The gearbox itself has already been used in
the US version of the X5 4.8i, however, a
different torque converter is used for the
diesel model.
 8

Technical data
The following table compares the M57D30T2
US engine with petrol engines that are offered
for the same models.
Designation N52B30O1 N54B30O0 N62B48O1 M57D30T2

Type Straight 6 Straight 6 V8 Straight 6

Displacement [cm3] 2996 2979 4799 2993

Firing order 1-5-3-6-2-4 1-5-3-6-2-4 1-5-4-8-6-3-7-2 1-5-3-6-2-4

Stroke/bore [mm] 88.0/85 88.9/84 88.3/93 90.0/84

Output at [kW/hp*] 193/260 225/300 261/350 200/265
engine speed [rpm] 6600 5800 6250 4200
Torque at [Nm/lbft] 305/225 407/300 475/350 580/428
engine speed [rpm] 2500 1400 3500 1750
Governed engine
[rpm] 7000 7000 6500 4800
speed limit
Power output per
[hp/l] 86.7 100 72.9 89.3
litre
Compression ratio ε 10.7 10.2 10.5 16.5
Cylinder spacing [mm] 91 91 98 91
Valves/cylinder 4 4 4 4

Intake valve ∅ [mm] 34.2 31.4 35.0 27.4

Exhaust valve ∅ [mm] 29.0 28.0 29.0 25.9
Main bearing
journal ∅ on [mm] 56 56 70 60
crankshaft
Big-end bearing
journal ∅ on [mm] 50 50 54 45
crankshaft
Fuel specification [RON] 98 98 98

Fuel [RON] 91-98 91-98 91-98 Diesel

18
 8

Engine
MSV80 MSD80 ME9.2.3 DDE7.3
management
Exhaust emission ULEVII
ULEVII ULEVII LEVII
standard US
* SAE-hp

Full load diagrams

To get an idea of the performance of the various petrol engines in the following full
load M57D30T2 US engine, it is compared to diagrams.

13 - M57D30T2 US
enginecompared to
N52B30O1 engine

By comparing these two 3 litre engines it can power output, the maximum torque of the
be clearly seen that, despite virtually identical diesel is almost double as high.
 8
14 - M57D30T2 US enginecompared to
N54B30O0 engine

This enormous
difference in
maximum torque
turbocharged 3
litre petrol engine
that has a is also
apparent when
comparing the
considerably
higher nominal power
output.

20
 8
15 - M57D30T2 US
enginecompared to N62B48O1
engine

Even the 4.8 litre V8 engine cannot achieve

the maximum torque of the 3 litre diesel
engine.
However, the decisive factor is the low engine
speeds at which the diesel engine develops
this high torque. This means that more power
is available in this range. In terms of power
output, the diesel engine is superior to any of
these petrol engines up to an engine speed of
4000 rpm.
 9
System components. Advanced Diesel.

Engine mechanical system

Only slight modifications have been made to The modifications include:
the engine mechanical system compared to
• C
rankcasethe Europe version.
• C
rankshaft and big-end bearings
• P
istons
• C
rankcase breather.

Crankshaft and big-end bearings

Only lead-free crankcase and big-end relating to environmental protection and the
bearings are used in the M57D30T2 US disposal of end-of-life vehicles.
engine. This conforms to requirements

Crankcase
In contrast to the Europe version, the In principle, the reinforcement panel serves to
M57D30T2 US engine has a larger enhance the stability of the crankcase.
reinforcement panel on the underside of the However, the enlargement was realized solely
crankcase. for acoustic reasons.
The reinforcement panel now covers four of Never drive the vehicle without the
the main bearing blocks for the crankshaft.
reinforcement panel. 1

Pistons
The piston pin has a greater offset than in the changes in piston contact. The acoustic
Europe version. The offset of the piston pin advantages of increasing the offset are further
means that the piston pin is slightly off centre. developed particularly at idle speed.
This provides acoustic advantages during

22
 9
Crankcase breather
The crankcase breather in the US version is The only probable reason for a leak in the
system would be that the blow-by pipe is not
connected to the cylinder head cover. To
facilitate protection of this situation by the
OBD,theheatinglineisroutedviaaconnector
tothecylinderheadcover(2).Essentially,this
connector serves only as a bridge so that
actuation of the heating system is looped
through. The plug connection is designed in
such a way that correct contact is made only
when the blow-by pipe has been connected
correctly to the cylinder head cover, i.e. the
contactfortheheatingsystemisnotclosedif
the blow-by pipe is not connected to the
cylinder head cover. OBD recognizes this
situation as a fault.

Index Explanation
1 Cylinder head cover
2 Blow-byheaterconnectorforOBD
monitoring
3 Blow-by heater connector at wiring
harness
4 Filtered air pipe
5 Intake air from intake silencer
6 Blow-by heater connector at blow-
1 -Blow-by pipe by pipe
generally heated. In addition, operation of the
crankcase breather is OBD monitored (On
Board Diagnosis). This is because a leaking
system would produce emissions.

23
 9
7 Intake air to exhaust turbocharger
8 Blow-by pipe

3 If the blow-by pipe is not connected to the

cylinder head correctly, the OBD will activate
the MIL (Malfunction Indicator Lamp). 1

Air intake and exhaust system

The M57D30T2 US engine exhibits the • Electric swirl flaps
following special features in the air intake and
• Electric exhaust gas recirculation valveexhaust system:
(EGR valve)
• Low pressure EGR
• Turbo assembly adapted for low pressureEGR.

24
 9

2 - Air intake and exhaust system - M57D30T2 US engine

Index Explanation Index Explanation

1 M57D30T2 US engine 18 Oxidation catalytic converter and
diesel particulate filter
2 Intake silencer 19 Exhaust gas temperature sensor
before oxidation catalytic converter
3 Hot-film air mass meter (HFM) 20 Oxygen sensor
4 Compressor bypass valve 21 Wastegate
5 Exhaust turbocharger, low pressure 22 Turbine control valve
stage

25
 9
6 Exhaust turbocharger, high pressure 23 Exhaust pressure sensor after
stage exhaust manifold
7 Bypass valve for high pressure EGR 24 Swirl flap regulator
cooler
8 High pressure EGR cooler 25 Boost pressure sensor
9 Temperature sensor, high pressure 26 Exhaust differential pressure sensor
EGR
10 High pressure EGR valve 27 NOx sensor before SCR catalytic
converter
11 Throttle valve 28 Temperature sensor after diesel
particulate filter
12 Charge air temperature sensor 29 Metering module (for SCR)
13 Intercooler 30 Mixer (for SCR)
14 Low pressure EGR valve with 31 SCR catalytic converter
positional feedback
15 Temperature sensor, 32 NOx sensor after SCR catalytic
low pressure EGR converter
16 Low pressure EGR cooler 33 Digital Diesel Electronics (DDE)
17 Exhaust gas temperature sensor 34 Rear silencer
after oxidation catalytic converter

Air intake system

Intake air system
The intake air system differs on the E70 and
E90. Both vehicles draw in unfiltered air
behind the BMW kidney grille.

3 - Air intake system E70 and E90

Index Explanation Index Explanation

26
 9
A Air intake system E70 3 Intake silencer (air cleaner housing)
B Air intake system E90 4 Hot-film air mass meter (HFM)
1 Intake 5 Filtered air pipe
2 Unfiltered air pipe 6 Blow-by pipe
On the E90, the intake silencer is located at to the vehicle. On the E70, the intake
silencer thefrontrightoftheenginecompartmentfixed is fixed over the engine.
Swirl flaps the US engine is the electric actuating system
with positional feedback.
The engine is equipped with the familiar swirl flapsinthetangentialport.Aspecialfeatureon

4 - Intake manifold with electric swirl flaps

Index Explanation Index Explanation

1 Linkage for operating the swirl flaps 5 Swirl port
2 Connection to throttle valve 6 Tangential port
3 Intake manifold 7 Swirl flaps
4 Electric motor

This system provides advantages in terms of

control, however, it is also a prerequisite for
meeting OBD requirements.

27
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Exhaust system

5 - E70 and E90 exhaust systems

Index Explanation Index Explanation

A Exhaust system E70 6 SCR catalytic converter
B Exhaust system E90 7 NOx sensor after SCR catalytic
converter
1 Oxygen sensor and concealed 8 Rear silencer
exhaust temperature sensor before
oxidation catalytic converter

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 9
2 Exhaust gas temperature sensor 9 Exhaust gas temperature sensor
after oxidation catalytic converter after diesel particulate filter
3 Differential pressure sensor 10 Metering module
4 NOx sensor before SCR catalytic 11 Diesel particulate filter
converter
5 Mixer

29
 9

Exhaust gas recirculation (EGR) speeds. This is why it is used in the heavier E70 as it
is often driven in the higher load ranges.
Exhaust gas recirculation is one of the available
options for reducing NOx emissions. Adding exhaust The advantage is based on the fact that a higher total
gas to the intake air reduces the oxygen in the mass of exhaust gas can be recirculated. This is made
combustion chamber, thus resulting in a lower possible for two reasons:
combustion temperature. • Lower exhaust gas temperature
The EGR systems in the E70 and E90 differ. The exhaust gas for the low pressure EGR is
Both vehicles are equipped with the familiar EGR tapped off at a point where a lower temperature
system. Due to its higher weight, the E70 additionally prevails than in the high pressure EGR.
features low pressure EGR, used for the first time at Consequently, the exhaust gas has a higher density
BMW. thus enabling a higher mass.
In addition, the exhaust gas is added to the fresh
Low pressure EGR
intake air before the exhaust turbocharger, i.e.
before the intercooler, where it is further cooled.
The lower temperature of the total gas enables a
higher EGR rate without raising the temperature in
the combustion chamber.
• Recirculation before the exhaustturbocharger
Unlike in the high pressure EGR where the exhaust
gas is fed to the charge air already compressed, in
this system the exhaust gas is added to the intake air
before the exhaust turbocharger. A lower pressure
prevails in this area under all operating conditions.
This makes it possible to recirculate a large volume
of exhaust gas even at higher engine speed and load
whereas this is limited by the boost pressure in the
high pressure EGR.

6 - Low pressure EGR

The known EGR system has been expanded by the

low pressure EGR on the E70. This system offers
advantages particularly at high loads and engine

30
 9
The following graphic shows the control of the Added to this, it
EGR system with low pressure EGR: is only activated
at a coolant
temperature of
more than 55 °C.
The low
pressure EGR
valve is closed as
from a certain
load level so that
only the high
pressure EGR
valve is active
again. This
means the EGR
rate is
continuously
reduced.

7 - Control of EGR system

Index Explanation Index Explanation

1 No exhaust gas recirculation 3 High and low pressure EGR are
active
2 Only high pressure EGR is active

As already mentioned, the low pressure EGR

hasthegreatestadvantageathigherloadsand is
therefore activated, as a function of the characteristic
map, only in this operating mode. The low pressure
EGR, however, is never active on its own but rather
always operatestogetherwiththehighpressureEGR.

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 9

8 - Installation position LP EGR

Index Explanation Index Explanation

1 Diesel particulate filter 4 Low pressure EGR
2 Turbo assembly 5 Exhaust system
3 Exhaust turbocharger, low pressure
stage
The low pressure EGR system is located on exhaust gas is branched off directly after the the right-hand side on
the engine directly next diesel particulate filter and fed to the intake air to the diesel particulate filter and the low
before the compressor for the low pressure pressure stage of the turbo assembly. The stage.

32
 9

9 - Low pressure EGR intake

nation
pressure EGR port
ered air intake
The following graphic shows the components of the low pressure EGR:

33
 9

10 - LP EGR components

Index Explanation Index Explanation

1 Temperature sensor, 5 Coolant infeed
low pressure EGR
2 Low pressure EGR valve 6 Coolant return
3 Connection for positional feedback 7 Low pressure EGR cooler
4 Vacuum unit for low 8 Sheet metal gasket with filter
pressure EGR valve

There is a fine meshed metal screen filter compressor blades of the exhaust
located at the exhaust gas inlet from the turbocharger. 3 The metal screen filter must
diesel particulate filter to the low pressure
be installed when fitting the low pressure EGR
EGR system. The purpose of this filter is to
cooler to the diesel particulate filter otherwise
ensure that no particles of the coating
there is a risk of the turbocharger being
particularly in a new diesel particulate filter can
damaged. 1
enter the low pressure EGR system. Such
particles would adversely affect the
High pressure EGR The exhaust gas recirculation known to date is

34
 9
referred to here as the high pressure EGR in
order to differentiate it from the low pressure
EGR.
Compared to the Europe version, the high
pressure EGR is equipped with the following
special features:
• Electric EGR valve with positional feedback
• Temperature sensor before high pressure
EGR valve

11 - High pressure EGR • EGR cooler with bypass.

12 - High pressure EGR system

Index Explanation Index Explanation

1 Coolant infeed 5 High pressure EGR cooler
2 High pressure EGR valve 6 Vacuum unit of bypass valve for high
pressure EGR cooler
3 Throttle valve 7 Coolant return
4 Temperature sensor, high pressure
EGR

The electric actuating system of the EGR • Pressure difference between exhaust
valve enables exact metering of the gaspressure in the exhaust manifold and
recirculated exhaust gas quantity. In addition, boost pressure in the intake manifold.
this quantity is no longer calculated based
solely on the signals from the hot-film air This enables even more exact control of the
mass meter and oxygen sensor but the EGR rate.
following signals are also used: The EGR cooler serves the purpose of
• Travel of high pressure EGR valve increasing the efficiency of the EGR system.
• Temperature before high pressure However, reaching the operating temperature
as fast as possible has priority at low engine
EGRvalve
temperatures. In this case, the EGR cooler

35
 9
can be bypassed in order to heat up the a flap which, in turn, is operated by a vacuum
combustion chamber faster. For this purpose, unit. The bypass is either only in the "Open"
a bypass that diverts the coolant is integrated or "Closed" position.
in the EGR cooler. This bypass is actuated by
Exhaust turbocharger
The US engine is equipped with the same
variable twin turbo as the Europe version,
however, the turbo assembly is modified due
to the low pressure EGR.
On the one hand, the inlet for the low
pressure EGR is located on the compressor
housing for the low pressure stage. On the
other hand, the compressor wheels are
nickel-coated to protect them from the
exhaust gas.

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 9

Cooling system
Thecoolingsystem,isinpart,vehicle-specific. TheE70andE90differwithregardtotheEGR In principle, there are
scarcely any differences cooler. Since the E70 is equipped with a low
between the cooling systems on petrol and pressure EGR system, it has a second EGR diesel engines.
cooler, the low pressure EGR cooler.
The two basic differences compared to petrol engines are:
• No characteristic map thermostat
• EGR cooler.

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 9

13 - X5 xDrive35d cooling system

Index Explanation Index Explanation

1 Radiator 10 Heating heat exchanger
Coolant-to-air heat exchanger
2 Gearbox cooler 11 Duo-valve
Coolant-to-air heat exchanger
3 Electric fan 12 Auxiliary coolant pump
4 Thermostat, gearbox oil cooler 13 Engine oil cooler
Engine oil-to-coolant heat exchanger
5 High pressure EGR cooler 14 Expansion tank
6 Thermostat 15 Gearbox oil cooler
Gearbox oil-to-coolant heat
exchanger
7 Coolant pump 16 Ventilation line

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 9

8 Low pressure EGR cooler 17 Additional radiator

Coolant-to-air heat exchanger
9 Coolant temperature sensor

14 - 335d cooling system

Index Explanation Index Explanation

1 Gearbox cooler 9 Heating heat exchanger
Coolant-to-air heat exchanger
2 Radiator 10 Duo-valve
Coolant-to-air heat exchanger
3 Additional radiator 11 Auxiliary coolant pump
Coolant-to-air heat exchanger
4 Thermostat, gearbox oil cooler 12 Engine oil cooler
Engine oil-to-coolant heat exchanger
5 High pressure EGR cooler 13 Expansion tank

39
 9

6 Thermostat 14 Gearbox oil cooler

Gearbox oil-to-coolant heat
exchanger
7 Coolant pump 15 Ventilation line
8 Coolant temperature sensor 16 Electric fan
Fuel preparation system

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 9
15 - Fuel preparation system, M57D30T2 US engine

The fuel Index Explanation Index Explanation

preparation
system differs A Fuel feed 6 Return line
neither in terms
B Fuel return 7 Feed line
of design layout
nor function from C Fuel high pressure 8 Fuel temperature sensor
the Europe
version. 1 Fuel rail pressure sensor 9 High-pressure line
However, some 2 High-pressure line 10 Fuel rail
components
have been 3 Leakage oil line 11 Restrictor
adapted to the 4 Piezo injector 12 High-pressure pump
different fuel
specification. 5 Fuel rail pressure control valve 13 Volume control valve
These components are:
• High-pressure pump
• Fuel rail
• Fuel injectors.
These adaptations are restricted to different
coatings and materials on the inside.

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 9
Overview of fuel supply system

16 - E90 Diesel fuel

supply system Index Explanation Index Explanation
Design 1 Fuel filler neck 5 Right-hand service opening
As for petrol
2 Left-hand service opening 6 Filler vent
engines, the fuel
system is 3 Fuel return line 7 Electric fuel pump controller
vehicle-specific.
There are, 4 Fuel filter with heating system

however, several general and significant differences • The breather system is significantly simpler
compared to petrol engine vehicles. • There is no carbon canister (AKF) and nofuel tank
These are: leakage diagnosis module (DMTL) • There is no
• The system includes a fuel return line pressure regulator

42
 9
• The fuel filter is not located in the fuel tank.
The design layout of the fuel supply systems in the
E70 and E90 are described in the following.

43
 9
E70 with diesel engine

17 - Fuel tank on E70 with diesel engine

Index Explanation Index Explanation

A Fuel filler cap 1 Initial fill valve
B Pressure relief valve 2 Intake mesh filter
C Non-return valve 3 Fuel pump
D Surge chamber 4 Pressure relief valve
E Fuel tank 5 Feed line
F Service cap 6 Return line
G Lever-type sensor 7 Leak prevention valve
H Filler vent valve 8 Suction jet pump
I Connection 9 Air inlet valve
J Maximum fill level 10 Suction jet pump
K Non-return valve 11 Pressure relief valve
L Filter

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 9
In addition to delivering the fuel to the engine, the fuel The fuel pump (3) with intake filter (2) is a part of the
supply system also filters the fuel. The fuel tank right-hand delivery unit. The surge chamber including
contains an additional venting system. a suction jet pump (10) with pressure relief valve (11)
and initial fill valve (1) as well as a lever-type sensor
The fuel tank is divided into two chambers because
of the space available in the vehicle. The fuel supply (G) complete this delivery unit.
system has two delivery units that are
accommodated in the right and left fuel tank halves.
The suction jet pump (8), lever-type sensor A line leads from the filler vent valve (H) to the (G), leak prevention
valve (7) and air inlet valve filter (L). The fuel filler pipe is connected to this (9) belong to the left-hand delivery unit.
line via the non-return valve (K).

E90 with diesel engine

18 - Fuel tank on E90 with diesel engine

Index Explanation Index Explanation

45
 9

A Fuel filler cap 1 Initial fill valve

B Pressure relief valve 2 Intake mesh filter
C Non-return valve 3 Fuel pump
D Surge chamber 4 Pressure relief valve
E Fuel tank 5 Feed line
F Service cap 6 Return line
G Lever-type sensor 7 Leak prevention valve
H Filler vent valve 8 Suction jet pump
I Connection 9 Non-return valve
J Maximum fill level 10 Suction jet pump
L Filter 11 Pressure relief valve
Functions of the fuel supply system

Fuel tank

19 - Fuel tank for E70 with diesel engine

Index Explanation Index Explanation

46
 9

A Fuel filler cap E Fuel tank

B Pressure relief valve F Service cap
C Non-return valve G Lever-type sensor
D Surge chamber

A pressure relief valve (B) is integrated in the Thefuelfilllevelcanbedeterminedviathetwo fuel filler cap (A) to
protect the fuel tank (E) lever-type sensors (G). from excess pressure. A non-return flap (C) is
The surge chamber (D) ensures that the fuel located at the end
of the fuel filler neck. The pump always has enough fuel available for non-returnflap preventsthefuel from
sloshing delivery. back into the fuel filler neck.
The components in the fuel tank can be reached via the two
service caps (F).

Fuel supply system

20 - Fuel supply system for E70 with diesel engine

Index Explanation Index Explanation

1 Initial fill valve 7 Leak prevention valve
2 Intake mesh filter 8 Suction jet pump

47
 9

3 Fuel pump 9 Air inlet valve

4 Pressure relief valve 10 Suction jet pump
5 Feed line 11 Pressure relief valve
6 Return line

In the event of the surge chamber being completely valve is used on the E90. The non-return valve ensures
empty, the initial filling valve (1) ensures that fuel that, while the engine is off, fuel from the right-hand
enters the surge chamber while refuelling. half of the fuel tank cannot flow back into the left-hand
The fuel reaches the fuel pump (3) via the intake filter half. The return system remains completely filled with
(2), then continues through the delivery line (5) to the fuel.
fuel filter. The fuel pump is located in the surge A further line branches off into the left-hand half of
chamber. A pressure relief valve (4) is integrated in the the fuel tank after the non-return valve (7) and
fuel pump to transports the fuel into the surge chamber via the
preventpressureinthedeliverylinefromrising too high. suction jet pump (8).
As the engine switches off, the delivery line is
depressurized but cannot run dry because, provided
the system is not leaking, no air is able to enter it. In
addition, after the fuel pump has switched off, the fuel
pressure/temperature sensor is checked for
plausibility.
Fuel that is required for lubrication and the function of
high pressure generation flows back into the fuel tank
via the return line (7). The fuel coming from the return
line is divided into two lines downstream of the leak
prevention valve (7). The non-return valve prevents
the fuel tank from draining in the event of damage to
lines on the engine or underbody. It also prevents the
return line from running dry while the engine is off.
One of the lines guides the fuel into the surge
chamber via a suction jet pump (10). The suction jet
pump transports the fuel from the fuel tank into the
surge chamber. If the fuel delivery pressure in the
return line increases too much, the pressure relief
valve (11) opens and allows the fuel to flow directly
into the surge chamber.
An air inlet valve is used in the E70. The air inlet valve
(9) ensures that air can enter the line when the engine
is off, preventing fuel from flowing back from the right-
hand half of the fuel tank to the left.
Instead of the air inlet valve (9) a non-return

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 9

Air supply and extraction

21 - Tank ventilation system for E70 with diesel engine

Index Explanation Index Explanation

H Filler vent valve K Non-return valve
I Connection L Filter
J Maximum fill level

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 9
Fuel ventilation is ensured by means of the filler vent and the fuel can flow from the fuel filler pipe into the
valve (H). tank.
The filler vent valve is located in the fuel tank and The filter (L) prevents dirt or insects from entering the
uses the connection (I) to determine the maximum fill ventilation and blocking the line. 3 If the ventilation
level (J). The filler vent valve
line does become blocked, fuel consumption during
contains a float that buoys upwards on the fuel when
operation would cause negative pressure and the fuel
the vehicle is refuelled and blocks the filler ventilation.
tank would be compressed and damaged. 1
The fuel rises in the fuel filler and the fuel nozzle
switches off. Index Explanation
A roll-over valve is also integrated in the filler vent
1 Valve head
valve to block the ventilation line when a certain
angle of incline is reached and prevents fuel from 2 Excess pressure spring
draining out if the vehicle were to roll over.
3 Brace
The non-return valve (K) prevents fuel from escaping
via the ventilation when the vehicle is refuelled. 4 Bottom section of housing
During operation, air can flow into the fuel filler pipe
5 Pressure relief valve
Components of the fuel supply system
6 Sealed housing

Pressure relief valve in fuel filler cap

50
9
The pressure relief valve ensures that, if there is a problem
with fuel tank ventilation, any excess pressure that may
form can escape and the fuel tank is not damaged.
If excess pressure forms in the fuel tank, this causes the
valve head (1) and with it the entire
pressure relief valve (5) to be lifted off the sealed housing
(6). The excess pressure can now escape into the
atmosphere. The excess pressure spring (2) determines
the opening pressure. The excess pressure spring uses a
defined pressure to push the pressure relief valve onto the
sealed housing and is supported by the brace (3).

22 - Pressure relief valve

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 9
Protection against incorrect refuelling

Index Explanation Index Explanation

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 9
23 - Protection
againstincorrect ∅ 21 mm Petrol fuel nozzle ∅ 24 mm Diesel fuel nozzle
refuelling

Index Explanation Index Explanation

1 Housing 5 Torsion spring
2 Locking lever 6 Rivet
3 Tension spring 7 Hinged lever
4 Flap 8 Ground strap
24 - Protection againstincorrect refuelling

The protection against incorrect refuelling feature nozzle with a diameter of approximately 24 mm can
ensures that the fuel tank cannot be filled with fit. If the diameter is approximately 21 mm, the flap
gasoline. As the previous graphic shows, only a fuel

53
 9
(4) does not open as the hinged lever (7) and the
locking lever (2) cannot be pushed apart.
If a diesel fuel nozzle is inserted, this pushes the
locking lever (2) and the hinged lever (7) at the same
time. The hinged lever is pushed outwards against the
tension spring (3) and releases the flap (4). This is only
possible, however, if the hinged lever cannot move
freely and is also locked in position by the fuel nozzle.

3 To open the protection against incorrect refuelling

feature in the workshop, a special tool is required. 1

54
 9

Fuel pump The electric fuel pump is located in the fuel tank.
There it is well protected against corrosion and the
Today's diesel vehicles are fitted with electric fuel
pump noise is adequately soundproofed.
pumps only. The electric fuel pump is designed to
deliver a sufficient amount of fuel to lubricate and
cool the injectors and the high-pressure pump and to
satisfy the maximum fuel consumption of the engine.
It has to deliver the fuel at a defined pressure. That
means that when the engine is idling or running at
medium power, the fuel pump delivers several times
more than the amount of fuel required. The fuel
pump delivers approximately three or four times the
volume of maximum possible fuel consumption.

25 - Electric fuel pump

Index Explanation Index Explanation

1 Impeller 6 Electrical connection
2 Drive shaft 7 Sliding contacts
3 Electric motor 8 Pressure chamber
4 Pressure relief valve 9 Intake section
5 Pressure connection

55
 9
The fuel pump on BMW diesel engines may either • Speed-regulated:
be a gear pump, a roller-cell pump or a screw-spindle The fuel pump operates with "ignition ON".
pump. The following fuel pumps are used on USA If the engine is not started, the fuel pump switches
vehicles: off again after a defined period. The fuel pump is
Vehicle Fuel pump controlled by an interposed control unit (fuel pump
controller) in response to a request signal from the
E70 Screw-spindle pump DDE. The fuel pump controller monitors and
E90 Gear pump regulates the pump speed. If the engine is
switched off, so too is the fuel pump.
The operating principle of each of these types of
pump is described below. The pump itself is • Pressure-regulated:
driven by the drive shaft (2) of the electric motor (3). The fuel pump operates with "ignition ON".
The electric motor is controlled by the electrical If the engine is not started, the fuel is switched off
connection (6) and sliding contacts (7). at a specific pressure. When the engine is running,
the fuel pump is regulated on-demand by the
Passing first through the intake filter and then the interposed fuel pump controller in response to a
remainder of the intake section (9), the fuel enters the load signal from the DDE in order to ensure a
impeller (1). The fuel is pumped through pressure uniform fuel pressure at the inlet to the high-
chamber (8) on the electric motor, past the pressure pressure pump.
connection (5) and onwards to the fuel filter and
engine. Bothspeedregulationandpressureregulation have
improved fuel economy, although it has been
If the fuel delivery pressure increases to an possible to improve fuel economy further still with
impermissible value, the pressure relief valve (4) pressure regulation. Other positive side effects
opens and allows the fuel to flow into the surge include an increase in the fuel pump's service life, an
chamber. unloading of the vehicle electrical system and a
reduction in fuel pump noise.
Control
Vehicle Control
In principle, there are three different types of fuel
pump control: E70 Pressure control
• Unregulated: E90 Speed control
The fuel pump operates with "ignition ON". Gear pump
If the engine is not started, the fuel pump switches
off again after a defined period. If the engine is The type of gear pump used is a rotor pump.
running, the fuel pump operates at maximum The rotor pump comprises an outer rotor (1) with
output and speed. teeth on the inside, and an inner rotor (4) with teeth
The fuel is switched off with "engine OFF". on the outside. The inner rotor is driven by the drive

56
 9
shaft (5) of the electric motor. The outer rotor is During the rotary motion, the spaces on the intake side
propelled by the teeth of the inner rotor and thus enlarge, while those on the pressure side become
turns inside the pump housing. proportionately smaller.
The inner rotor has one tooth fewer than the outer Thefuelisfedintotherotorpumpthroughtwo grooves in
rotor, which means that, with each revolution, fuel is the housing, one on the intake side and one on the
carried into the next tooth gap of the outer rotor. pressure side. Together with the tooth gaps, these
grooves form the intake section (6) and pressure
section (3).

26 - Gear pump/rotor pump

Index Explanation
1 Outer rotor
2 Fuel delivery to the engine
3 Pressure section

57
 9

4 Inner rotor
5 Drive shaft
6 Intake section
7 Fuel from the fuel tank
Screw-spindle pump
With the screw-spindle pump, two screw spindles
intermesh in such a way that the flanks form a seal with each
other and the housing. In the displacement chambers
between the housing and the spindles, the fuel is pushed
towards the pressure side with practically no pulsation.
In this way, the screw spindles pump fuel away
from the fuel tank (5). The fuel is then fed to
the engine (3) through the pump housing and the fuel
delivery line.
27 - Screw-spindle pump

Index Explanation
1 Drive shaft screw spindle
2 Gearwheel
3 Fuel delivery to the engine
4 Screw spindle
5 Fuel from the fuel tank

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 9

Fuel filter
The fuel filter with heater illustrated here was 3 BMW recommends the use of parts and
used in vehicle models with diesel engine and accessories for the vehicle that have been
distributor injection pump. Later models with approved by BMW for this purpose. These
diesel engine and common rail system are parts and accessories have been tested by
equipped with the following fuel filters. BMW for their functional safety and
compatibility in BMW vehicles. BMW accepts product
responsibility for them. However, BMW cannot accept any
liability for nonapproved parts or accessories. 1
The job of the fuel filter is to protect the fuel system against
dirt contamination. The highpressure pump and injectors in
particular are very sensitive and can be damaged by even the
tiniest amounts of dirt. The fuel delivered to the engine is
always fed through the fuel filter. Contaminants are trapped
by a paperlike material. The fuel filter is subject to a
replacement interval.
28 - Fuel filter with heater (later vehicle models)

Index Explanation
1 Fuel filter heater connection
2 Inlet into the fuel filter heating
3 Locking clamp
4 Fuel filter
5 Connection between fuel line and
high-pressure pump

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 9

Fuel filter heater • A defined fuel delivery pressure isexceeded due to

cold, viscous fuel.
The fuel filter heater is attached to the fuel filter
housing and fixed with a locking clamp. The fuel If the filter is clogged, a corresponding signal is sent via
flows through the fuel filter heating into the fuel filter. a diagnosis line to the DDE. This is the case when,
despite a sufficiently high temperature, the fuel
Since winter-grade diesel fuel remains thin even at low
pressure upstream of the filter does not drop.
temperatures, the fuel filter heater is not normally
active when winter-grade diesel fuel is used. In order Pressure-controlled system
to save energy, the fuel filter heater is only switched
on when the diesel actually becomes viscous due to The fuel filter heater is actuated by the DDE. A
low temperatures. combined fuel pressure and temperature sensor
upstream of the high pressure pump is used.
There are two different control systems depending on
whether the fuel supply system is speed-controlled or The fuel filter heater is switched on when both of the
pressure-controlled. following conditions are fulfilled:
• Temperature drops below a defined value
Speed-controlled system
• The required fuel pressure is not reacheddespite
The fuel filter heater is not controlled by the DDE. A increased power intake of the electric fuel pump.
pressure switch and a temperature sensor are
located in the fuel filter housing. The DDE recognizes a clogged filter when the target
pressure upstream of the high pressure pump is not
Overview of selective catalytic reduction reached despite
a sufficiently high
The fuel filter heater is switched on when both of the fuel temperature and high power intake of the electric
following conditions are fulfilled: fuel pump.
• Temperature drops below a defined value Selective catalytic reduction is a system for reducing
nitrogen oxides (NOx) in the exhaust gas. For this

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 9
purpose, a reducing agent (ureawater solution) is The nitrogen oxide reduction reaction then takes
injected into exhaust gas downstream of the diesel place in the SCR catalytic converter.

29 - Simplified representation of SCR system

particulate filter.

61
 9
The urea-water solution is carried in two reservoirs in
the vehicle. The quantity is measured out such that it
is sufficient for one oil change interval.
The following graphic shows a simplified
representation of the system:

62
 9

Index Explanation Index Explanation The larger,

unheated
1 Passive reservoir 10 Pump reservoir is the
passive
2 Level sensors 11 Filter
reservoir. A
3 Filler pipe, passive reservoir 12 Transfer line pump regularly
transfers the
4 Metering line 13 Metering module ureawater
5 Metering line heater 14 Level sensor solution from
the passive
6 Pump 15 Filler pipe, active reservoir reservoir to the
7 Function unit 16 Exhaust system active reservoir.

8 Heater in active reservoir 17 SCR catalytic converter

9 Active reservoir

The reason for using two reservoirs is that the urea-

water solution freezes at a temperature
of-11 °C.Forthisreason,thesmallerreservoir is heated
but the larger reservoir not. In this way, the entire
volume of the urea-water solution need not be
heated, thus saving energy. The amount is sufficient,
however, to cover large distances.
The small, heated reservoir is referred to as the active
reservoir. A pump conveys the ureawater solution
from this reservoir to the metering module. This line is
also heated.

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 9

Installation locations in the E70

64
 9
30 - Installations locations, E70 SCR system

Index Explanation Index Explanation

1 Active reservoir 8 Passive reservoir
2 Delivery module 9 Metering module
3 Filler for active reservoir 10 Exhaust gas temperature sensor
after diesel particulate filter
4 Transfer unit 11 NOx sensor before SCR catalytic
converter
5 Filter 12 Filler for passive reservoir
6 SCR catalytic converter 13 Oxidation catalytic converter and
diesel particulate filter
7 NOx sensor after SCR catalytic
converter
On the E70, the active reservoir, including the underbody, approximately under the driver's
delivery unit, is located on the right-hand side seat. The transfer unit is installed on the right
directly behind the front bumper panel. The in the underbody. Both fillers are located in the
passive reservoir is located on the left in the engine compartment.

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 9

Installation locations in the E90

31 - Installations locations, E90 SCR system

66
 9
Index Explanation Index Explanation
1 Active reservoir 8 Passive reservoir
2 Delivery module 9 Metering module
3 Filler for active reservoir 10 Exhaust gas temperature sensor
after diesel particulate filter
4 Transfer unit 11 NOx sensor before SCR catalytic
converter
5 Filter 12 Filler for passive reservoir
6 SCR catalytic converter 13 Oxidation catalytic converter and
diesel particulate filter
7 NOx sensor after SCR catalytic
converter
OntheE90,boththeactivereservoiraswellas the
passive reservoir are located under the luggage
compartment floor with the active reservoir being
the lowermost of both. The fillers are located on
the left-hand side behind the rear wheel where
they are accessible through an opening in the
bumper panel. The
fillers are arranged in the same way as the
reservoirs, i.e. the lowermost is the filler for the
active reservoir. The transfer unit and the filter are
located behind the filler.

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 9

Detailed system overview

32 - SCR system overview

Index Explanation Index Explanation

1 Operating vent 19 Filter
2 Passive reservoir 20 Metering line heater
3 Level sensors 21 Metering line
4 Filler vent 22 Operating vent
5 Filler pipe 23 Temperature sensor
6 Transfer line 24 Level sensor

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7 Delivery module 25 Intake line heater

8 Delivery module heater 26 Filter
9 Delivery pump 27 Active reservoir
10 Reversing valve 28 Heating element in function unit
11 Filter 29 Function unit
12 Pressure sensor 30 Filler pipe
13 Filter 31 Metering module
14 Restrictor 32 NOx sensor before SCR catalytic
converter
15 Extractor connections 33 Exhaust gas temperature sensor
after diesel particulate filter
16 Filler vent 34 SCR catalytic converter
17 Non-return valve 35 NOx sensor after SCR catalytic
converter
18 Transfer pump

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E70 System circuit diagram

33 - E70 SCR system circuit diagram

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Index Explanation Index Explanation

1 Heater module 10 Exhaust gas temperature sensor
after diesel particulate filter
2 Delivery module with delivery pump, 11 Transfer pump
reversing valve, pressure sensor and
heater
3 Function unit with level sensor in 12 Power distributor, battery
active reservoir, temperature sensor
and heater
4 Active reservoir 13 Passive reservoir
5 Metering line heater 14 Level sensors in passive reservoir
6 Digital Diesel Electronics (DDE) 15 Evaluator, level sensors in passive
reservoir
7 NOx sensor after SCR catalytic 16 DDE main relay
converter
8 NOx sensor before SCR catalytic 17 Power distributor, junction box
converter
9 Metering module 18 Evaluator, level sensor in active
reservoir

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E90 System circuit diagram

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34 - E90 SCR system circuit diagram

Index Explanation Index Explanation

1 DDE main relay 11 Transfer pump
2 Digital Diesel Electronics (DDE) 12 Evaluator, level sensor in active
reservoir
3 SCR relay 13 Function unit with level sensor in
active reservoir, temperature sensor
and heater
4 Power distributor, junction box 14 Active reservoir
5 Exhaust gas temperature sensor 15 Delivery module with delivery pump,
after diesel particulate filter reversing valve, pressure sensor and
heater
6 Metering module 16 Heater module
7 Power distributor, battery 17 NOx sensor after SCR catalytic
converter
8 Passive reservoir 18 NOx sensor before SCR catalytic
converter
9 Level sensors in passive reservoir 19 SCR load relay
10 Evaluator, level sensors in passive 20 Metering line heater
reservoir

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Functions of selective catalytic reduction system

Selective catalytic reduction is currently the This system carries a reducing agent,
most effective system for reducing nitrogen ureawater solution, in the vehicle.
oxides (NOx). During operation, it achieves
an efficiency of almost 100 % and approx.
90 % over the entire vehicle operating
range. The difference is attributed to the
time the system requires until it is fully
operative after a cold start.
The urea-water solution is injected into the exhaust A temperature sensor in the exhaust pipe after the
pipe by the metering module upstream of the SCR diesel particulate filter (i.e. before the SCR catalytic
catalytic converter. The DDE calculates the quantity converter) and the metering module also influences
that needs to be injected. The nitrogen oxide content this function. This is because injection of the urea-
in the water solution only begins at a minimum temperature
exhaust gas is determined by the NOx sensor before of 200 °C.
the SCR catalytic converter. Corresponding to this 36 - Nitrogen oxides

value, the exact quantity of the urea-water solution

Ammonia
(NH3) is used
for the
purpose of
reducing the
nitrogen
oxides in a
special
catalytic
converter.

35 - SCR functions

Index Explanation Index Explanation

1 NOx sensor before SCR catalytic 3 NOx sensor after SCR catalytic
converter converter
2 Metering module 4 Temperature sensor after diesel
particulate filter
required to fully reduce the nitrogen oxides is injected.
The urea-water solution converts to ammonia in the
exhaust pipe. In the SCR catalytic converter, the
ammonia reacts with the nitrogen oxides to produce
nitrogen (N2) and water (H2O). 37 - Ammonia

A further NOx sensor that monitors this function is

located downstream of the SCR catalytic converter. The ammonia is supplied in the form of a ureawater
solution.

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ThetaskoftheSCRsystemistosubstantially
reduce the nitrogen oxides (NOx) in the
exhaust gas. Nitrogen oxides occur in two
different forms:
•Nitrogen monoxide (NO)
•Nitrogen dioxide (NO 2).

38 -Urea-water solution

The urea-water solution is injected by the

metering system into the exhaust system
downstreamof thedieselparticulate filter.The required
quantity must be metered exactly as otherwise
nitrogen oxides or ammonia would emerge at the end.
The following description of the chemical processes
explains why this is the case.

Conversion of the urea-water solution

The uniform distribution of the urea-water solution in
the exhaust gas and the conversion to ammonia take
place in the exhaust pipe upstream of the SCR
catalytic converter.

Initially, the urea ((NH2)2CO) dissolved in the urea-

water solution is released.

39 - Release of urea from the urea-

water solution

The conversion of urea into ammonia takes

place in two stages.

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40 - Thermolysis: Urea
converts to ammonia Thermolysis
and isocyanic acid

This means, only Explanation: During thermolysis, the urea-water solution is split into two products
a part of the as the result of heating.
urea-water Initial product: Urea ((NH2)2CO)
solution is
converted into Result: Ammonia (NH3)
ammonia during Isocyanic acid (HNCO)
thermolysis. The
remainder, Chemical formula: (NH2)2CO → NH3 + HNCO
which is in the
form of isocyanic acid, is converted in a second step.
Hydrolysis

Explanation: The isocyanic acid that was produced during thermolysis is converted
into ammonia and carbon dioxide (CO2) by the addition of water in the
hydrolysis process.
Initial products: Isocyanic acid (HNCO)

Water (H2O)
Result: Ammonia (NH3)
Carbon dioxide (CO2)
Chemical formula: HNCO + H2 O → NH3 + CO2

41 - Hydrolysis: Isocyanic acid reacts with water to form ammonia and carbon dioxide

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The water required for this purpose is also Therefore, following hydrolysis, all the urea is provided by
the urea-water solution. converted into ammonia and carbon dioxide.

Nitrogen oxides are converted into harmless

nitrogen and water in the SCR catalytic
converter.

42 -Nitrogen and water

Reduction
Explanation: The catalytic converter serves as a "docking" mechanism for the
ammonia molecules. The nitrogen oxide molecules meet the
ammonia molecules and the reaction starts and energy is released.
This applies to NO in the same way as to NO2.
Initial products: Ammonia (NH3)
Nitrogen monoxide (NO)
Nitrogen dioxide (NO2)
Oxygen (O2)
Result: Nitrogen (N2)
Water (H2O)
Chemical formulae: NO + NO2 + 2NH3 → 2N2 + 3H2O

4NO + O2 + 4NH3 → 4N2 + 6H2O

6NO2 + 8NH3 → 7N2 + 12H2O

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43 - NOx reduction: Nitrogen oxides react with ammonia to form nitrogen and water

It can be seen that each individual atom has would emerge if too little urea-water solution
found its place again at the end of the were injected. By the same token, ammonia
process, i.e. exactly the same elements are on would emerge if too much urea-water
the left as on the right. This takes place only solution were injected, resulting in unpleasant
when the ratio of the urea-water solution to odour and possible damage to the
nitrogen oxides is correct. Nitrogen oxides environment.

SCR control
The SCR control is integrated in the digital divided into the metering system control
and diesel electronics (DDE). The SCR control is the metering strategy.

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44 -

Index Explanation Index Explanation

1 Digital diesel electronics DDE7 10 Pressure sensor
2 SCR control 11 Temperature sensor in active
reservoir
3 Metering system control 12 Outside temperature sensor
4 Metering strategy 13 Level sensor in active reservoir
5 Injection pump 14 Level sensor in passive reservoir
6 Transfer pump 15 NOx sensor before SCR catalytic
converter
7 Metering module 16 NOx sensor after SCR catalytic
converter
8 Heater 17 Exhaust temperature sensor
9 Reversing valve

Metering strategy However, the NOx sensor must reach its operating
The metering strategy is an integral part of the SCR temperature before it can start measuring.
control that calculates how much areawater solution is Depending on the temperature, this can take up to
to be injected at what time. 15 minutes. Until then the DDE uses a substitute
value to determine the amount of nitrogen oxide in
During normal operation, the signal from the NOx the exhaust gas.
sensor before the SCR catalytic converter is used for
the purpose of calculating the quantity. This sensor A second NOx sensor is installed after the SCR
determines the quantity of nitrogen oxide in the catalytic converter for the purpose of monitoring the
exhaust gas and sends the corresponding value to system. It measures whether there are still nitrogen
the DDE. oxides in the exhaust gas. If so the injected quantity
of the ureawater solution is correspondingly adapted.
The NOx sensor, however, measures not only

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nitrogen oxides but also ammonia but cannot 2 Correct quantity of little urea-water
distinguish between them. solution injected
If too much urea-water solution is injected, although 3 Too much urea-water solution
the nitrogen oxides are completely reduced so-called
injected
"ammonia slip" occurs, i.e. ammonia emerges from
the SCR catalytic converter. This in turn causes a rise This, however, is a long-term adaptation and not a
short-term control process as the SCR
in the value measured by the NOx sensor. The aim,
catalyticconverterperformsastoragefunction for
therefore, is to achieve a minimum of the sensor
ammonia.
value.
Metering system control
The metering system control could be considered as
the executing part. It carries out
therequirementssetbythemeteringstrategy. This
includes both the metering, i.e. injection as well as the
supply of the urea-water solution.
The tasks of the metering system control during
normal operation are listed in the following:
Metering of the urea-water solution:
• Implementation of the required targetquantity of
urea-water solution
45 - Nitrogen and ammonia emission diagram • Feedback of the implemented actualquantity of
Index Explanation urea-water solution.
Supplying urea-water solution:
A Value output by NOx sensor
• Preparationofmeteringprocess(fillinglinesandpress
B Injected quantity of urea-water urebuilt-up)undercorresponding ambient
solution conditions (temperature) • Emptying lines during
1 Too little urea-water solution afterrunning
injected • Heater actuation.

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In addition, the metering system control recognizes
faults, implausible conditions or critical situations and
initiates corresponding measures.
The metering strategy determines the quantity of The metering quantity is also determined over a longer
urea-water solution to be injected. The metering period of time. This long-term calculation is reset
during refuelling
or can be reset
by the BMW
Metering of the urea-water solution diagnosis
system control executes this request. A part of the system.
function is metering actuation that determines the Supplying urea-water solution
actual opening of the metering valve.
A supply of a urea-water solution is required for the
Depending on the engine load, the metering valve selective catalytic reduction process. It is necessary
injects at a rate of 0.5 Hz to 3.3 Hz. to store this medium in the vehicle and to make it
The metering actuation facility calculates the available rapidly under all operating conditions. In this
following factors in order to inject the correct case 'making available' means that the urea-water
quantity: solution is applied at a defined pressure at the
metering valve.
• The duty factor of the actuator of themetering
valve in order to determine the injection duration Various functions that are described in the following
are required to carry out this task.
• Actuation delay to compensate for
thesluggishness of the metering valve. Heater
The signal from the pressure sensor in the metering The system must be heated as the urea-water
line is taken into account to ensure an accurate solution freezes at a temperature of -11 °C.
calculation; the pressure, however, should remain at a
constant 5 bar. The heating system performs following tasks:
The metering system control also calculates the • To monitor the temperature in the activereservoir
quantity actually metered and signals this value back and the ambient temperature
to the metering strategy. • To thaw a sufficient quantity of urea-watersolution
and the components required for

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metering the solution during system startup
• To prevent the relevant componentsfreezing
during operation
• To monitor the components of the heatingsystem.
The following components are heated:
• Surge chamber in active reservoir
• Intake line in active reservoir
• Delivery module (pump, filter, reversingvalve)
• Metering line (from active reservoir tometering
module).
The heating systems for the metering line and delivery
module are controlled dependent on the ambient
temperature.
The heater in the active reservoir is controlled as a
function of the temperature in the active reservoir.
Theheatingcontrolisadditionallygovernedby the
following conditions:

Temperature in active reservoir and ambient temperature are the same Condition 1
Condition 2 Condition 3 Condition 4
Ambient temperature and > -4 °C < -4 °C < -5 °C < -9 °C
temperature in active reservoir
Metering line heater Not active Not active Active Active
Active reservoir heater Not active Active Active Active
Metering standby Established Established Established Delayed

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 9
Metering standby is delayed at a temperature considerablylowerthanthetemperatureinthe active
below -9 °C in the active reservoir, i.e. a defined waiting reservoir. In this case, the ambient temperature is
period is allowed to elapse until an attempt to build up taken for the delay in metering standby.
pressure begins. This time is constant from -9 °C to - The following graphic shows the delay as a function
16.5 °C as of the temperature sensor signals.
it is not possible to determine to what extent the
urea-water solution is frozen. At temperatures below
-16.5 °C, the heating time is extended until an
attempt to build up the pressure is made.
Heating the metering line generally takes
placemuchfaster.Therefore,thetemperature in the
active reservoir is the decisive factor for the period of
time until an attempt to build up the pressure is
undertaken. However, it is possible that the heating
time for the metering line is longer at ambient
temperature
46 - Diagram - metering
standby delay times
the active
reservoir is
longer than the
delay caused by
the ambient
temperature.
Only the times at
temperatures
below -9 °C are
relevant as they
are shorter than
3 minutes at
temperatures
above -9 °C. 3
Index Explanation Index Explanation minutes is the
time that the
A Delay as a function of temperature in B Delay as a function of ambient entire system
active reservoir temperature requires to
establish
t [s] Delay time in seconds T [°C] Temperature in degrees Celsius
metering
The graphic shows that, with the same temperature standby (e.g. also taking into account the temperature
signals, the delay time relating to the temperature in in the SCR catalytic converter). This is also the time
that is approved by the EPA (Environmental Protection

83
 9
Agency) as the preliminary period under all operating
conditions. This time is extended significantly at very
low temperatures.
The following example shows how the delay time up
to metering standby is derived at low temperatures.
Example: Ambient temperature: -30 °C, temperature
in active reservoir: -12 °C
The vehicle was driven for a longer period of time at
very low ambient temperatures of 30 °C. The heater in
the active reservoir has thawed the urea-water
solution. The vehicle is now parked for a short period
of time (e.g. 30 minutes). When restarted, the
temperature in the active reservoir is -12 °C.
The delay time that is initiated by the temperature in
the active reservoir is approx. 18 minutes while the
delay time initiated by the ambient temperature is 25
minutes. Since the delay time initiated by the ambient
temperature is longer, this will give rise to a longer
delay.
Now another condition comes into play. Only the end
of the delay caused by the temperature in the active
reservoir can enable metering. This means:
• The delay time initiated by the temperaturein the
active reservoir will have elapsed after 18 minutes.
No enable is yet provided by the second delay
caused by the ambient temperature. A second
cycle of 18 minutes now begins.
• The delay time initiated by the
ambienttemperature will elapse after 25 minutes
and will send its enable signal. However, this delay
cannot enable metering.
• The second cycle of the delay time causedby the
temperature in the active reservoir will have
elapsed after 36 minutes. Since the enable from
the delay caused by the ambient temperature is
now applied, metering will be enabled.

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Transfer pumping relates to pumping the urea-water solution If the passive
from the passive reservoir into the active reservoir was
So-called transfer pumping is required since reservoir. refilled, transfer
two reservoirs are used for storing the ureawater solution. pumping will
The term transfer pumping only take place
after a quantity
of approx. 3 l has
been used up in
the active
reservoir. The
entire quantity is
then pumped
over. The
system then
waits again until
a quantity of
approx. 3 l has
been used up in
the active
reservoir before
again pumping
the entire
quantity while
simultaneously
47 - Transfer pumping starting the
Index Explanation Index Explanation incorrect refilling
detection
1 Passive reservoir 6 Pump function. This
2 Level sensors 7 Non-return valve function
determines
3 Extractor connections 8 Level sensor whether the
4 Transfer line 9 Active reservoir system has
been filled with
5 Filter the wrong
medium as it is
The following conditions must be met for transfer present in high concentration in the active reservoir.
pumping:
Transfer pumping does not take place in the event of
• Thereisaurea-watersolutioninthepassivereservoir a fault in the level sensor system.
• The ambient temperature is above aminimum
value of -5 °C for at least 10 minutes
• A defined quantity (300 ml) was used up inthe
active reservoir or the reserve level in the active
reservoir was reached.
The solution is then pumped for a certain time
in order to refill the active reservoir. The transfer
pumping procedure is terminated if the "full" level is
reached before the time has elapsed.

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 9
Delivery • Heater provides a
speed
The urea-water solution is delivered from the • Pressure sensor
active reservoir to the metering module. This
• Filtertask
is performed by a pump that is integrated in the delivery unit.
The delivery unit • Return throttle additionally contains:
• Reversing
valve.

48 - Delivery

Index Explanation Index Explanation

1 Metering line 8 Filter
2 Delivery module 9 Level sensor
3 Pump 10 Filter
4 Reversing valve 11 SCR catalytic converter
5 Filter 12 Exhaust system
6 Restrictor 13 Metering module
7 Pressure sensor

The pump is actuated by a pulse-width modulated specification for the purpose of establishing
signal (PWM signal) from the DDE. The PWM signal

86
 9
the system pressure. The value for the speed
specification is calculated by the DDE based on the
signal from the pressure sensor.
When the system starts up, the pump is actuated with
a defined PWM signal and the line to the metering
module is filled. This is followed by pressure build-up.
Only then does pressure control take place.
When the metering line is filled, the opened metering
valve allows a small quantity of the urea-water
solution to be injected into the exhaust system.
During pressure control, i.e. during normal operation
with metering, the pump is actuated in such a way that
a pressure of 5 bar is applied
in the metering line. Only a small part of the urea-
water solution delivered by the pump is
actuallyinjected.Themajorityofthesolutionis
transferred via a throttle back into the active reservoir.
This means, the delivery pressure is determined by
the pump speed together with the throttle cross
section.
The solution is
injected four
times per
second. The
quantity is
determined by
the opening
time and stroke
of the metering
valve.
However, the
quantity is so
low that there is
no noticeable
drop in
pressure in the
metering line.

Evacuating

Afterturningofftheengine,thereversingvalve switches
to reverse the delivery direction of the pump, thus
evacuating the metering line and metering module.

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49 - Evacuating
liquid as opposed to an actual change in the liquid level
Evacuation also
takes place if the Index Explanation Index Explanation
system has to be
1 Metering line 8 Filter
shut down due
to a fault or if the 2 Delivery module 9 Level sensor
minimum
temperature in 3 Pump 10 Filter
the active 4 Reversing valve 11 SCR catalytic converter
reservoir can no
longer be 5 Filter 12 Exhaust system
maintained.
6 Throttle 13 Metering module
This is necessary
to ensure no 7 Pressure sensor
urea-water in the reservoir.Lowlevelisthereforesignalledwhen
solution remains in the metering line or metering thecorrespondingsensorisnolongercovered by the
module as it can freeze. urea-water solution for a defined period of time. Once
The metering valve is opened during evacuation. the level drops below this value, it can no longer be
reached during normal operation. This means, the
Level measurement liquid sloshing on the sensor or driving uphill/downhill
There are level sensors both in the active as well as in is no longer interpreted as a higher liquid level.
the passive reservoir. However, these sensors are not
continuous sensors as in the fuel system for example.
They can determine only a specific point, to which a
defined quantity of urea-water solution in the
reservoir is assigned.
Two separate level sensors are fitted in the passive
reservoir, one for "full" and one for "empty". The
signals from the level sensors are not sent directly to
the DDE but rather to an evaluator.
The active reservoir contains one level sensor that
has various measuring points:
• Full
• Warning
50 - Example: Level signal OK
• Empty.
Index Explanation
Also in this case, there is an evaluator installed
between the sensors and the DDE, which fulfils the 1 Measuring point "Full"
same tasks as for the passive reservoir.
2 Measuring point "Warning"
This evaluator sends a plausible level signal to the
DDE. It recognizes changes in the fill level caused, for 3 Measuring point "Empty"
example, by driving uphill/downhill or sloshing of the
Level of urea-water solution Level signal
Level > Full Full
Full > Level > Warning OK
Warning > Level > Empty Warning
Empty > Level Empty

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 9
4 Reference calculation is calibrated together with the level
measurement.
5 Level
Every time the level drops below a level sensor the
The level measurement system must also recognize corresponding amount of urea-water solution in the
when the active and passive reservoirs are refilled. This reservoir is stored. The amount of urea-water solution
is achieved by comparing the current level with the actually injected is then subtracted from this value
value last stored. while the pumped quantity is added.
The level sensor signal after refilling corresponds to This makes it possible to determine the level more
the signal while driving uphill. To avoid possible precisely than that would be possible by simple
confusion, the refilling recognition function is limited measurement. In addition, the level can still be
to a certain period of time after starting the engine determined in the event of one of the level sensors
and driving off - as it can be assumed that refilling will failing.
only take place while the vehicle is stationary.
Since it is possible that refilling is not recognized, the
A certain vehicle speed must be exceeded to ensure calculation is continued only until the level ought to
that sloshing occurs, thus providing a clear indication drop below the next lower sensor.
that the system has been refilled.
Example:
Refilling the system while the engine is running can
also be detected but with modified logic. The signals Once the level drops below the "full" level sensor, for
sent by the sensors while the vehicle is stationary are example, from now on the quantity of used and
also used for this purpose. The vehicle must be repumped urea-water solution is taken into account
stationary for a defined minimum period in order to and the actual level below "full" calculated. Normally,
make the filling plausible. the level then drops below the next lower level sensor
at the same time as determined by the level
When the urea-water solution is frozen, a level sensor calculation. An adjustment takes place at this point and
will show the same value as when it is not the calculation is restarted.
wetted/covered by the solution. A frozen reservoir is
therefore shown as empty. For this reason, the If, however, a quantity of urea-water solution is refilled
following sensor signals are used for measuring the without it being detected, the actual level will be higher
level: than the calculated level. The level calculation is
stopped if it calculates that the level ought to have
• Ambient temperature• Temperature in active dropped below the
reservoir next level sensor but the level sensor is still
wetted/covered.
• Heater enable.
By way of exception, a defective level sensor can
Level calculation cause the calculation to continue until the reservoir is
empty.
This function calculates the quantity of ureawater
solution remaining in the active reservoir. The

SCR system modes

When the ignition is switched on, the SCR other. The following graphic shows the
control undergoes a logical sequence of sequence of modes which are subsequently
modes in the DDE. There are conditions that described. initiate the change from one
mode to the

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 9

51 - Sequence of modes in SCR control

INIT (SCR initialization) when no faults occur in the system. In this mode, the
system is waiting for the pressure control enable that
The control unit is switched on (terminal 15 ON) and
the SCR system is initialized. is provided by the following sensor signals:
• Temperature in catalytic converter
STANDBY (SCR not active)
• Temperature in active reservoir• Ambient
STANDBY mode is assumed either after initialization
temperature
or in the case of fault.
• Engine status (engine running).
AFTERRUN mode is assumed if terminal 15 is
switched off in this state or a fault occurs. The system also remains in
NOPRESSURECONTROL mode for a
NOPRESSURECONTROL (waiting for enable for pressure minimum period of time so that a plausibility check of
control) the pressure sensor can be performed.
NOPRESSURECONTROL mode is assumed PRESSURECONTROL mode is assumed once the
enable is finally given.

90
 9
STANDBY mode is assumed if terminal 15 is time, the system switches to the next mode of
switched off or a fault occurs in METERINGCONTROL. If the required pressure
NOPRESSURECONTROL mode. built-up is not achieved after the defined period of
time has elapsed, a status
PRESSURECONTROL (SCR system running) loopisinitiated,andVENTILATIONmodeis assumed.
PRESSURECONTROL mode is the normal operating If the pressure cannot be built up after a defined
status of the SCR system and has four submodes. number of attempts, the system signals a fault and
assumes
PRESSURECONTROL mode is maintained until
PRESSUREREDUCTION mode.
terminal 15 is switched off. A change to
PRESSUREREDUCTION mode then takes place. PRESSUREREDUCTION mode is also
assumed when terminal 15 is switched off or
A change to PRESSUREREDUCTION mode also
takes place if a fault occurs in the system. another fault occurs in the system.
• VENTILATION
The four submodes of
PRESSURECONTROL are described in the following: If the pressure could not be increased beyond a
certain value in
• REFILL
PRESSUREBUILDUP mode, it is assumed that
The delivery module, metering line and the metering there is still air in the pressure line.
module are filled when REFILL mode is assumed.
The metering valve is opened for a defined period
The pump is actuated and the metering valve
of time to allow this air to escape. This status is
opened by a defined value. The fill level is
exited after this time has elapsed and the system
calculated.
returns to PRESSUREBUILDUP mode. The loop
The mode changes to PRESSUREBUILDUP when between PRESSUREBUILDUP and VENTILATION
the required fill varies corresponding to the
level is reached or a defined pressure increase is conditionofthereducingagent.Thereason for this is
detected. that a different level is established after REFILL
PRESSUREREDUCTION mode is depending on the ambient conditions. Repeating
the ventilation function will ensure that the
assumed if terminal 15 is switched off or a fault
pressure line is completely filled with reducing
occurs in the system.
agent.
• PRESSUREBUILDUP
PRESSUREREDUCTION mode is
In this mode, the pressure is built up to a certain assumed if terminal 15 is switched off or a fault
value. For this purpose, the pump is actuated while occurs in the system.
the metering valve is closed.
• METERINGCONTROL
If the pressure is built up within a certain

91
 9
The system can enable metering in NOPRESSURECONTROL mode is also assumed
METERINGCONTROL mode. This is the when terminal 15 is switched on.
actual status during normal operation. The urea-
water solution is injected in this mode. AFTERRUN
In this mode, the pump is actuated in such The system is shut down in AFTERRUN mode.
awaythatadefinedpressureisestablished. This If terminal 15 is switched on again before afterrun has
pressure is monitored. If the pressure progression been completed, afterrun is
overshoots or undershoots defined parameters, a cancelled and STANDBY mode is assumed. If
fault is detected and the system assumes
this is not the case the system goes through the
PRESSUREREDUCTION mode. These
submodes of AFTERRUN.
faults are reset on return to
METERINGCONTROL mode. • TEMPWAIT (catalytic converter cooling phase)
PRESSUREREDUCTION mode is also In AFTERRUN mode, TEMPWAIT
assumed if terminal 15 is switched off or another submode is initially assumed if the system is filled.
fault occurs in the system. This is intended to prevent excessively hot exhaust
gasses being drawn into the SCR system.
PRESSUREREDUCTION
The duration of the cooling phase is determined by
Metering enable is cancelled on entering the exhaust gas temperature. EMPTYING
PRESSUREREDUCTION mode. submode is assumed after this time, in which the
This status reduces the pressure in the delivery exhaust system cools down, has elapsed.
module, metering line and the metering module after EMPTYING submode is also assumed if a fault
PRESSURECONTROL mode. For this occurs in the system.
purpose,thereversingvalveisopenedandthe pump
actuated at a certain value, the metering valve is If terminal 15 is switched on in this status,
closed. STANDBY mode is assumed.
PRESSUREREDUCTION mode ends when the • EMPTYING
pressure drops below a certain value. The system The system assumes
assumes NOPRESSURECONTROL AFTERRUN_EMPTYING submode after the
mode if the pressure threshold is reached (undershot) cooling phase. The pressure line and the delivery
within a defined time. module are emptied in this submode. The urea-
The system signals a fault if the pressure does not water solution is drawn back into the active reservoir
drop below the threshold after a defined time has by opening the reversing valve, actuating the pump
elapsed. In this case or also in the and opening the metering valve. This is intended to
case of another fault, the system assumes prevent the urea-water solution freezing in the
NOPRESSURECONTROL mode. metering line or the metering module.

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Thelevelinthemeteringlineiscalculatedin this mode. To ensure the driver is not caught out, a warning and
PRESSURECOMPENSATION mode is assumed if shut-down scenario is provided that begins at a
the metering line is empty. sufficiently long time before the vehicle actually shuts
down so that the driver can either conveniently top up
PRESSURECOMPENSATION mode is
the ureawater solution himself or have it topped up.
also assumed if a fault occurs in the system. If
terminal 15 is switched on, STANDBY mode is Warning scenario
assumed. The warning scenario begins when the level drops
• PRESSURECOMPENSATION (intake line - After executing the steps correctly the below the
ambient pressure) system assumes "Warning" level
WAITING_FOR_SHUTOFF submode. sensor in the
After the system has been completely
active reservoir.
emptied, PRESSURECOMPENSATION WAITING_FOR_SHUTOFF is also
At this point, the
submode is assumed. In this status the assumed if a fault occurs in the system.
active reservoir is
pump is switched off, the reversing valve is If terminal 15 is switched on, STANDBY still
then closed followed by the metering valve mode is assumed. approximately 50
after a delay. The time interval between WAITING_FOR_SHUTOFF (shutting % full with urea-
switching off the pump and closing the down SCR) water solution.
valve prevents a vacuum forming in the The level is then
intake line; pressure compensation The control unit is shut down and determined as a
between the intake line and ambient • switched off. defined volume
pressure takes place. (depending on
type of vehicle).
From this point
Warning and shut-down scenario on, the actual
consumption of
The SCR system is relevant to the vehicle complying the urea-water solution is subtracted from this value.
with the exhaust emission regulations - it is a The mileage is recorded when the amount of 2500 ml
prerequisite for approval/ homologation! If the system is reached.
fails, the approval will be invalidated and the vehicle
must no longer be operated. A very plausible case A countdown from 1000 mls now takes place -
leading to the system failure is that the ureawater irrespective of the actual consumption of the urea-
solution runs out. water solution. The driver receives a priority 2 (yellow)
check control message showing the remaining range.
Vehicle operation is no longer permitted without the
urea-water solution, therefore, the engine will no
longer start.

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52 - CC message in 54 - CC message in
instrumentcluster, range < 1000 mls instrumentcluster, range < 200 mls

If the vehicle is equipped with In this case the following

an on-board computer (CID - message is shown in the CID:
Central Information Display),
instruction will also be
displayed.

55 - CC message in CID, range < 200 mls

53 - CC message in CID, range < 1000 mls

The driver receives a priority 1 (red) check control

message as from 200 mls.

Shut-down scenario Exhaust fluid incorrect

If the range reaches 0 mls, similar as to in the Ifthesystemisfilledwithanincorrectmedium, fuel
gauge, three dashes are shown instead of this will become apparent after several
the range. hundred miles (kilometres) later by elevated

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The check control message in the CID

changes and shows that the engine can no
longer be started.

58 -CC message in instrument

cluster in the case of
incorrect exhaust fluid

Theexclamationmarkinthesymbolidentifies
the fault in the system.
In this case, the message in the CID informs
the driver to go to the nearest workshop.

57 -CC message in CID, range=0mls

Inthiscase,itwillnolongerbepossibletostart
theengineifithasbeenshutdownforlonger
than three minutes. This is intended to allow
thedrivertomoveoutofahazardoussituation
if necessary.
If the system is refilled only after engine start
has been disabled, the logic of the refill
recognition system is changed in this special
case, enabling faster refill.
nitrogen oxide values in the exhaust gas
despite adequate injection of the supposed
urea-water solution. The system recognizes
an incorrect medium when certain limits are
exceeded. From this point on, a warning and
shut-down scenario is also initiated that
allows a remaining range of 200 mls.
56 - CC message in instrument cluster,
range = 0 mls

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 9
59 - CC message in CID in the case of incorrect exhaust fluid

Refilling
The active and passive reservoirs can be refilled with
urea-water solution either by the service workshop or

by the customer himself.

The system can be refilled without any
problemswiththevehicleonaninclineofupto
5° in any direction. In this case, 90 % of the maximum
possible fill is still achieved.
The volume of the urea-water solution reservoir is
designed such that the range is large enough to
cover one oil change interval. This means the
"normal" refill takes place as part of the servicing work
in the workshop. If, however, the supply of urea-water
solution should run low prematurely due to
extraordinarydrivingprofile,itispossibletotop up a
smaller quantity.

Refilling in service workshop

Refilling in the service workshop refers to the routine
refill as part of the oil change procedure. This takes
place at the latest after:
• 13000 mls on the E90,• 11000 mls on the
E70 or
• one year.
In this case, the system must be emptied first in order
to remove older urea-water solution.
This takes place via the extractor connections in the
transfer line. Although a small residual quantity always
remains in the reservoirs, it is negligible.

Topping up
Any required quantity can be topped up if the urea-
water solution reserve does not last up to the next oil
change. Ideally, this quantity
should only be as much as is required to reach the next
oil change, as the system is then emptied.

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 9

Components of the selective catalytic reduction system The urea-water

solution is not
toxic. It is an
Urea-water solution aqueous solution which, according to valid European
chemical law, poses no special risks. It is not a
The urea-water solution is the carrier for the ammonia
hazardous substance and it is not a dangerous
that is used to reduce the nitrogen
medium as defined by transport laws.
oxides (NOx) in the exhaust gas. To protect persons
and the environment from the effects of ammonia and If small amounts of the product come in contact with
to make it more easy to handlefor transportand the skin while handling the ureawater solution it is
refuellingprocedures, it is provided in an aqueous urea sufficient to simply rinse it off with ample water. In this
solution for the SCR process. way, the possibility of any ill effects on human health
are ruled out.
The recommended urea-water solution is
AdBlue. The VDA (Association of German Degradability and disposal
Automobile Industry) holds the rights to the
The urea-water solution can be broken down by
trademark AdBlue. AdBlue is a high-purity, water-
microbes and is therefore easily degradable. The
clear, synthetically manufactured 32.5 % urea
urea-water solution poses a minimum risk to water
solution that is standardized in accordance with DIN
and soil. In Germany, the urea-water solution is
70070/AUS32.
categorized in the lowest water hazard class (WGK 1).
The urea-water solution used must correspond to this In view of its excellent degradability properties, small
standard. quantities of spilt urea-water solution can be flushed
into the sewage system with ample water.
Health and safety

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 9
Materials compatibility storage and filling systems should be set up in such a
Contact of urea-water solution with copper and zinc as way that a temperature range from 30 °C to -11 °C is
well as their alloys and aluminium must be avoided as ensured.
this leads to corrosion. No problems whatsoever are Provided the recommended storage temperature of
encountered with stainless steel and most plastics. maximum 25 °C is maintained, the urea-water solution
meets the requirements stipulated by the standard
Storage and durability DIN 70070 for at least 12 months after its
To avoid adverse effects on quality due to manufacture. This period of time is shortened if the
contamination and high testing expenditure, the urea- recommended storage temperature is exceeded. The
water solution should only be handled in storage and urea-water solution will become solid if cooled to
filling systems specifically designed for this purpose. temperatures below -11 °C. When heated up, the
In view of the fact that the urea-water solution freezes frozen ureawater solution becomes liquid again and
can be used without any loss in quality.
solid at a temperature of -11 °C and decomposes at an
accelerated rate at temperatures above 25 °C, the Avoid direct UV radiation.

Passive reservoir
The passive reservoir is the larger of the two
supply reservoirs.

Vehicle Volume Location Position of filler neck

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 9

E70 16.5 l In underbody, approximately On the left in engine

under driver's seat compartment, under unfiltered
air pipe
E90 14.4 l Under luggage compartment Left side in rear bumper panel
floor instead of multifunction pan

The name passive reservoir refers to the fact • Level sensors (2x) that it is not heated.
• Operating vent (2x on
E90)
The following components make up the

Index Explanation Index Explanation

1 Operating vent 5 Fill line connection
2 Filler vent 6 "Empty" level sensor
3 "Full" level sensor 7 Passive reservoir

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4 Operating vent

• Filler vent.passive
reservoir:

60 - E90 Passive reservoir

The passive reservoir on the E70 is encased in

insulation as it is positioned near the front of
the exhaust system where the heat transfer to the urea-
water solution would be very high.

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 9

Index Explanation Index Explanation

1 Connection for transfer line 5 Fill line connection
2 Operating vent 6 Filler vent
3 "Full" level sensor 7 "Empty" level sensor

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 9
61 - Insulation of
4 Passive reservoir passive reservoir E70

62 - E70 Passive reservoir

Level sensors
There are two level sensors in the passive
reservoir. One supplies the "Full" signal and
the other the "Empty" signal.
The sensors make use of the conductivity of
the urea-water solution. Two contacts
project into the reservoir. When these
contacts are wetted with urea-water solution
the circuit is closed and current can flow,
thus enabling a sensor signal.
The two level sensors send their signal to an The "Full" level sensor is located at the top
evaluator. This evaluator filters the signals and of the passive reservoir. Both contacts are
recognizes, for example, sloshing of the wetted when the passive reservoir is
ureawater solution and transfers a completely filled and the sensor sends the
corresponding level signal to the digital diesel "Full" signal.
electronics. The "Empty" level sensor is located at the
bottom end of the passive reservoir. The
reservoir is considered to be "not empty" for
as long as the sensor is covered by urea-

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 9
water solution. The evaluator detects that the Venting
passive reservoir is empty when no sensor The passive reservoir is equipped with one
signal is received.
operating vent (2 in the E90) and one filler
63 - Level sensor in passive reservoir

vent.
The operating vent is directed into atmosphere. A so-called sintered tablet ensures that no
impurities can enter the reservoir via the operating vent. This sintered tablet consists of a
porous material and serves
as a filter that allows particles only up to a certain size to pass through.
The filler vent is directed into the filler pipe and therefore no filter is required.

Transfer unit
The transfer unit pumps the urea-water This pump is designed as a diaphragm pump.
solution from the passive reservoir to the It operates in a similar way to a piston pump
active reservoir. There is a screen filter in the but the pump element is separated from the
inlet port of the pump. mediumbyadiaphragm.Thismeansthereare
no problems regarding corrosion.

Index Explanation
1 Connection for transfer line to
passive reservoir (inlet)
2 Pump motor connection
3 Connection for transfer line to
active reservoir (outlet)

64 -Transfer unit

Active reservoir
The active reservoir is the smaller of the two energy is required to heat the urea-water
reservoirs and its name refers to the fact that it solution.
is heated. In view of its small volume, little
Vehicle Volume Location Position of filler neck
E70 6.4 l On front right in side panel On front right in engine
module between bumper panel compartment at the end of the
and wheel arch support carrier cross member
E90 7.4 l Behind the rear axle differential Left side in rear bumper panel
directly under the passive
reservoir

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 9

65 - E90
Active reservoir

Index Explanation Index Explanation

1 Active reservoir 4 Filler vent
2 Operating vent 5 Fill line connection
3 Delivery module 6 Connection of transfer line from p

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Index Explanation
1 Fill line connection, active reservoir
2 Delivery module
3 Metering line
4 Filler vent
5 Connection of transfer line from
passive reservoir
6 Active reservoir

66 - E70 Active reservoir

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 9
Function unit Index Explanation
The so-called function unit is located in the
1 Operating vent
active reservoir. It has the external appearance of
a surge chamber and accommodates a heater, 2 Bowl
filter and a level sensor. The delivery unit is
attached to it. 3 Level sensor
Unlike a surge chamber in the fuel tank, the
lower section of the function unit has slots.
This chamber creates a smaller volume in the
reservoir that scarcely mixes with the
ureawater solution outside the chamber.
There is a PTC heating element (positive
temperature coefficient) in the base of the
chamber that can heat up this smaller volume
at a relatively fast rate. The intake line is also
heated. In this way, liquid urea-water solution
can be made available for vehicle operation
even at the lowest temperatures.
The heating element in the chamber is
connected to the heater for the intake line to
form one heating circuit. A power
semiconductor supplies the current for this
heating circuit. The power semiconductor is
controlled by the DDE. The DDE can
determine the current that flows across the
heating elements and can therefore monitor
their operation.

67 - Function unit

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 9
68 - Sectional view of functionunit

Index Explanation Index Explanation

1 Level sensor 4 Intake line with heater
2 Heating element 5 Operating vent
3 Filter

The temperature sensor provides the signal

for the heating control system. It is designed
as an NTC sensor (negative temperature
coefficient). The temperature sensor is Index Explanation
integrated at the bottom end of the level
sensor. 3 "Empty" contact

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 9
The level sensor in the function unit provides
the level value for the entire active reservoir.
The level sensor in the active reservoir
operates in accordance with the same
principle as the level sensors in the passive
reservoir. In this case, however, there is only
one sensor with several contacts that extend
at different levels into the active reservoir.
The sensor makes use of the conductivity of
the urea-water solution. A total of four
contacts project into the reservoir. When
these contacts are wetted with urea-water
solution the circuit is closed and current can
flow, thus enabling a sensor signal.
Three contacts are responsible for signalling
the different levels. The fourth contact is the
reference, i.e. the contact via which the
electric circuit is closed. This reference
contact cannot be seen in the figure as it is
located directly behind the "Empty" contact
(3).
The level sensor sends its signal to an
evaluator. This evaluator filters the signal and 69
- Level sensor in active reservoir
recognizes, for example, sloshing of the
ureawater solution and transfers a Index Explanation
corresponding level signal to the digital
diesel electronics. 1 "Full" contact

2 "Warning" contact

Delivery unit
The delivery unit is located on the active
reservoir at the top end of the function unit.
Among other things, the delivery unit
comprises the pump that transfers the
ureawater solution from the active reservoir
to the metering module. The delivery unit is
also heated by a PTC element.

108
Metering module and mixer

71 - Metering module

Index Explanation Index Explanation

1 Metering line connection 2 Metering valve connection

70 - Delivery unit

Index Explanation Index Explanation

1 Pump motor and heater connection 3 Pressure sensor connection
2 Reversing valve connection 4 Metering line connection
The heating element in the delivery unit is controlled by the DDE. The DDE can
connected to the heater for the metering determine the current that flows across the
line to form one heating circuit. A power heating elements and can therefore monitor
semiconductor supplies the current for this their operation.
heating circuit. The power semiconductor is
Pump metering line while the pump delivers in the same
direction. It is designed as a4/2-
The pump is a common part with the pump in the
wayvalveinterchangesthemeteringline and intake line
transfer unit. While the engine is running, it pumps the
to the pump.
urea-water solution from the active reservoir to the
metering module. It sucks the The valve is not actuated in intervals and therefore has
meteringlineemptywhentheengineisturned off. only two positions. Since power is permanently
applied to the valve when it is actuated, the maximum
Pressure sensor actuation time is limited in order to avoid overheating.
The pressure sensor measures the pressure in the The metering module is responsible for injecting the
delivery line to the metering module. The value is urea-water solution into the exhaust pipe. It features a
transferred to the DDE. valve that is similar to the fuel injector in a petrol
Reversing valve engine with intake manifold injection.

The reversing valve ensures the delivery direction in

the metering line can be reversed to empty the

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 9

Although the metering module does not have The metering module is actuated by a pulsewidth
aheater,itisstillheatedbytheexhaustsystem to such an modulated (PWM) signal from the DDE such that the
extent that it even requires cooling fins. pulse duty factor determines the opening duration of
the valve.
72 - Metering module in installed position

Index Explanation Index Explanation

1 Mixer 4 Diesel particulate filter
2 NOx sensor before SCR catalytic 5 Metering module
converter
3 Exhaust gas temperature sensor 6 Insert
after diesel particulate filter
The metering module is equipped with a Mixer
tapered insert (6) that prevents urea-water

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 9

The mixer mounted in the flange connection

solution residue drying up and clogging the of the exhaust pipe is located directly behind
valve. Its shape creates a flow that prevents
the metering module in the exhaust system.
It urea-water solution from collecting on the swirls the flow of exhaust gas to ensure the walls
of the exhaust system. Urea deposits on urea-water solution is thoroughly mixed with the
insert are burnt off as it is heated to very the exhaust gas. This is necessary to ensure high
temperatures by the flow of exhaust gas. the urea converts completely into ammonia.

Index Explanation Index Explanation

1 Pump flow 1st chamber 5 Barrier 2
2 Catalytic element 6 Solid electrolyte zircon dioxide
(ZrO2)

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 9

3 Nitrogen outlet 7 Barrier 1

4 Pump flow 2nd chamber

112
 9

The nitrogen oxide sensor consists of the

actual measuring probe and the
corresponding control unit. The control unit
communicatesviatheLoCANwiththeengine
control unit.
Intermsofitsoperatingprinciple,thenitrogen
oxide can be compared with a broadband
oxygen sensor. The measuring principle is
basedontheideaofbasingthenitrogenoxide
measurement on oxygen measurement.
The following graphic shows the functional
principle of this measuring system.

73 -NO x sensor

113
 9
The exhaust gas flows through the NOx sensor. Here,
only oxygen and nitrogen oxides are of interest. In the
first chamber, the oxygen is ionized out of this mixture
with the aid of the first pump cell and passed through
the solid electrolyte. A lambda signal can be tapped off
from the pump current of the first chamber. In this way,
the exhaust gas in the NOx sensor is liberated from free
oxygen (not bound to nitrogen).
The remaining nitrogen oxide then passes through
the second barrier to reach the second chamber of
the sensor. Here, the nitrogen oxide is split by a
catalytic element into oxygen and nitrogen. The
oxygen released in this way is again ionized and can
then pass through the solid electrolyte. The pump
current that occurs during this process makes it
possible to deduce the quantity of oxygen and the
nitrogen level can be concluded from this quantity.

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Engine electrical system • Preheating system with LIN-bus link andceramic
heater plugs

In contrast to the ECE version of the M57D30T2 • Additional OBD sensors

engine, the US version of the engine electrical
• Electrically operated swirl flap and EGRvalve
system features following differences:
• Additional actuators and sensors forthe
• Engine control unit DDE7 lowpressure EGR system.
Engine control unit DDE7.3 The reason for this is that the capacity of
the DDE6 is no longer sufficient for the
The new DDE7 engine control unit that will
additional functions (especially SCR).
otherwise be used in the next generation of
diesel engines (N47, N57) is used in the US
version of the M57D30T2 engine.

Preheating system • System voltage

The heating system is responsible for providing • Status signal, starter enable.
reliable cold start properties and smooth operation The digital diesel electronics sends the required
when the engine is cold. heater plug temperature to the heating control unit to
The DDE control unit sends the temperature activate heating.
requirement of the heater plug to the heating control The heating system assumes various operating
unit. The heating control unit implements the request modes that are explained in the following.
and actuates the heater plugs with a pulse-width
modulated signal. The heating control unit additionally Preheating
sends diagnosis and status information via the LIN-bus
connection back to the digital diesel electronics. Preheating is activated after terminal 15 has been
switched on.
The LIN-bus is a bi-directional data interface that The heater system indicator in the instrument cluster
operates in accordance with the masterslave is activated at a coolant temperature of ≤ 10 °C.
principle. The DDE control unit is the master. Preheating is finished when:
Each of the six heating circuits can be diagnosed • The engine speed threshold of 42 rpm isexceeded
individually. (starter is operated) or
When the heating control unit is switched on • the preheating time has elapsed. Thepreheating
forthefirsttime,theelectricalresistanceofthe heater time is dependent on the coolant temperature and
plugs is evaluated at the start of the is defined in a characteristic curve.
heating process. A hot heater plug has a much
higherresistancethanacoldplug.Ifhotheater plugs are
detected based on their resistance, less power is Coolant Preheating time temperature in
applied to the heater plugs at the start of the heating seconds
cycle. If, on the other hand, cold heater plugs are in °C
detected, the maximum
powerisappliedtotheheaterplugsatthestart of the < -35 3.5
heating cycle. This function is known as dynamic -25 2.8
repeat heating. This function avoids the situation
where too much power is applied to a heater plug, -20 2.8
which is already hot, as the result of a second heating -5 2.1
cycle following shortly after the first, and therefore
overheats. 0 1.6
The DDE control unit determines the necessary 5 1.1
heater plug temperature as a function of the following
operating values: 30 1.1
• Engine speed > 30 0
• Intake air temperature Start standby heating
• Injected quantity Start standby heating is activated when the
preheating process is terminated by the preheating
• Ambient pressure time elapsing. Start standby heating is terminated:

115
 9
• After 10 secondsor • Valid key
• whentheenginespeedthresholdof42rpmis • Terminal R
exceeded. • Clutch operated.
Start heating Partial load heating
Start heating is activated during every engine start Partial load heating can occur at coolant temperatures
procedure when the coolant temperature is below 75
below 75 °C after starting the engine. Actuation of the
°C. Start heating begins after the engine speed
heater plugs depends on the engine speed and load,
threshold of 42 rpm has been exceeded. Start heating thus improving the exhaust gas characteristics.
is terminated:
• After the maximum start heating time of Actuation and fault detection
60seconds has elapsed or The power output stages for heater plug actuation are
• after the engine start operation has located in the heater control unit. The heater control
beencompleted or unit does not have its own fault code memory. Faults
in the heating system detected by the heater control
• when the coolant temperature of 75 °C is unit are signalled via the LIN-bus to the digital diesel
exceeded. electronics. The corresponding fault codes are then
stored in the DDE fault code memory.
Emergency heating
Toavoiddamage,theheatercontrolunitshuts down all
Emergency heating is triggered for 3 minutes in the heating activities when the permissible operating
event of communication between the DDE control temperature of the heater control unit is exceeded.
unit and heating control unit failing for more than 1
second. The heating control unit then uses safe The ceramic heater plugs are designed for an
values so as to prevent damage to the heating operating voltage of 7.0 to 10.0 V. A voltage of 10 V
system. can be applied to heat up the plug at a faster rate
during the heating process. A PWM
Concealed heating signal is applied to the heater plugs for the purpose of
maintaining the heater plug temperature.
Preheating and start standby heating are activated as Consequently, an effective voltage is established at the
so-called concealed heating up to a coolant
heater plugs that is lower than the system voltage. 3
temperature of 30 °C.
The ceramic heater plugs are susceptible
Concealed heating is triggered a maximum of toimpactandbendingloads.Heaterplugsthat have been
4 times and is then not enabled again before the dropped may be damaged. 1
engine is restarted.
Concealed heating is triggered by the following 3 A maximum voltage of 7 V may be applied to the
signals: heater plugs when removed. Higher voltages without
cooling air movement can irreparably damage the
• Driver's seat occupancy
heater plugs. 1
• Driver's seat belt buckle

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 9
Sensors and actuators
In the M57D30T2 US engine, the this system. The table below provides an modifications to the sensors
and actuators are overview. It shows a comparison between the restricted to the air intake and exhaust
system. E70 US and E90 US and the EURO4 version Several new components have been added to of
the ECE variant.
Sensors EURO4 E70 US E90 US
Outside temperature sensor 7 7 7
Ambient pressure sensor 7 7 7
Hot-film air mass meter (HFM) 7 7 7
Intake air temperature sensor (in HFM) 7 7 7
Charge air temperature sensor 7 7 7
Boost pressure sensor 7 7 7
Exhaust pressure sensor at exhaust manifold 7 7

Oxygen sensor 7 7 7
Exhaust gas temperature sensor before 7 7 7
oxidation catalytic converter
Exhaust gas temperature sensor before 7 7 7
diesel particulate filter
Exhaust backpressure sensor before diesel 7 - -
particulate filter
Exhaust differential pressure sensor - 7 7
Temperature sensor after - 7 -
low pressure EGR cooler
Temperature sensor after - 7 7
high pressure EGR cooler
Exhaust gas temperature sensor before - 7 7
SCR catalytic converter
NOx sensor before SCR catalytic converter - 7 7

NOx sensor after SCR catalytic converter - 7 7

Positional feedback, swirl flaps - 7 7
Positional feedback high - 7 7
pressure EGR valve
Positional feedback low - 7 -
pressure EGR valve
Blow-by connection - 7 7

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 9
OBD function Actuators EURO4 E70 US E90 US
The engine Compressor bypass valve EUV EUV EUV
management
has the Turbine control valve EPDW EPDW EPDW
additional task of
Wastegate EPDW EPDW EPDW
monitoring all
exhaust-relevant Throttle valve EL EL EL
systems to
ensure they are Swirl flaps EUV EL EL
functioning High pressure EGR valve EPDW EL EL
correctly. This
task is known as Low pressure EGR valve - EPDW EPDW
OnBoard Bypass valve for high pressure EGR cooler - EUV EUV
Diagnosis (OBD).
The malfunction SCR metering valve EL EL EL
indicator lamp
(MIL) is activated EL = Electrically operated
if the onboard EUV = Pneumatically operated via electric changeover valve
diagnosis
EPDW = Pneumatically operated via electropneumatic pressure
registers a fault.
converter
The events specific to US diesel engines that cause particulate filter regeneration cycles, an irreversible
the MIL to light up are described in the following. fault is stored and the MIL is activated.
SCR catalytic converter
Oxidation catalytic converter
The effectiveness of the SCR catalytic converter is
The oxidation catalytic converter is monitored with
regard to its conversion ability which diminishes with monitored by the two NOx catalytic converters.
ageing. The conversion of hydrocarbons (HC) during The nitrogen mass is measured before and after the
cold start is used as the indicator as heat is produced SCR catalytic converter and a sum is formed over a
as part of the chemical reaction and it follows a defined defined period of time. The actual reduction is
temperature progression after the oxidation catalytic compared with a calculated value that is stored in the
converter. DDE.
The exhaust gas temperature sensor after the The following conditions must be met for this
oxidation catalytic converter measures the purpose:
temperature. The DDE maps the temperature
progression during cold start and compares it to • NOx sensors plausible
calculated models. The result determines how • Metering active
effective the oxidation catalytic converter is operating.
A reversible fault is stored if the temperature • Ambient temperature in defined range
progression drops below a predetermined value. If this • Ambient pressure in defined range
fault is still determined after two successive diesel
• Regeneration of diesel particulate filter notactive

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 9
• SCR catalytic converter temperature indefined If the defined pressure threshold cannot be reached
range (is calculated by means of exhaust within a certain time, the metering module is opened
temperature sensor before SCR catalytic in order to vent the metering line. This is followed by
converter) a new attempt to build up pressure.
• Flow of exhaust gas in defined range. A reversible fault is stored if a defined number of
Monitoring involves four measuring cycles. A pressure build-up attempts remain unsuccessful. If the
reversible fault is stored if the actual value is lower fault is determined in two successive driving cycles, an
than the calculated value. If the fault is determined in irreversible fault is stored and the MIL is activated.
two successive driving cycles, an irreversible fault is This monitoring takes place only once per driving
stored and the MIL is activated. cycle before metering begins. Continuous pressure
Long-term adaptation is implemented, where the monitoring begins after this monitoring run was
metered quantity of urea-water solution is adapted, to successful.
ensure the effectiveness of the SCR catalytic Aconstantpressureoftheurea-watersolution
converter over a long period of time. To execute this (5 bar) is required for the selective catalytic reduction
adaptation procedure, the signal of the NOx sensor process. The actual pressure is measured by the
after the SCR catalytic converter is compared with a pressure sensor in the delivery module and compared
calculated value. If variations occur, the metered with a minimum and a maximum pressure threshold.
quantity is correspondingly adapted in the short term. A reversible fault is stored if the limits are exceeded
The adaptations are evaluated and a correction factor for a certain time. If the fault is determined in two
is applied to the metered quantity. successive driving cycles, an irreversible fault is
stored and the MIL is activated.
The operating range for the long-term adaptation is
the same as that for effectiveness monitoring. This monitoring run takes place while metering is
active.
A reversible fault is stored if the correction factor
exceeds a defined threshold. If the fault Level measurement in active reservoir
isdeterminedintwosuccessivedrivingcycles, an
irreversible fault is stored and the MIL is activated. A level sensor with three contacts at different heights
is used for the active reservoir. The plausibility of the
Supplying urea-water solution sensor is checked in the evaluator in that it checks
whether the signals are logical. For example, it is
A supply of a urea-water solution is required to ensure
improbable that the "Full" contact is covered by the
efficient operation of the SCR catalytic converter. solution while the "Empty" contact is not.
Once the SCR catalytic converter has reached a In this case, the evaluator sends a plausibility error to
certain temperature (calculated by the exhaust gas the DDE. This takes place at a pulse duty factor of 30
temperature sensor before the SCR catalytic % of the PWM signal. A reversible fault is set. If the
converter), the metering control system attempts to fault is determined in two successive driving cycles, an
build up pressure in the metering line. For this irreversible fault is stored and the MIL is activated.
purpose, the metering module must be closed and the
delivery pump This monitoring procedure only takes place if the
actuated at a certain speed for a defined period of temperature in the active reservoir is above a defined
time. value.

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If the line between the evaluator and at least one • Measured value outside the defined rangefor a
contact of the level sensor is interrupted, the fault is certain period of time
signalled to the DDE by a PWM signalwith40 • Operating temperature is not reached aftera
%pulsedutyfactor.Areversible
defined heating time
fault is set. If the fault is determined in two successive
driving cycles, an irreversible fault is stored and the • The distance from the measured value tozero is
MIL is activated. too great in overrun mode (no nitrogen oxides
expected)
Suitable urea-water solution • During the transition from load to overrunmode,
The SCR system is monitored with regard to refilling the signal of the NOx sensor does not drop fast
with an incorrect medium. This monitoring function enough from 80 % to 50 % (only NOx sensor
starts when refilling is detected. Refilling detection is before SCR catalytic converter)
described in the section on the SCR system.
Effectiveness monitoring of the SCR catalytic • If, despite a peak in the signal of the NOx sensor
converter is used for the purpose of determining before the SCR catalytic converter, at least a
whether an incorrect medium has been used. An defined change in the signal of the NOx sensor
incorrect medium is detected if the effectiveness after the SCR catalytic converter is not determined
drops below a certain value within a defined period of this is interpreted as implausible.
time after refilling. A reversible fault is set in this case.
If the fault is determined in two successive driving Exhaust gas recirculation (EGR)
cycles, an irreversible fault is stored and the MIL is During normal operation, the exhaust gas
activated. recirculation is controlled based on the EGR ratio.
In addition, the warning scenario with a remaining During regeneration of the diesel particulate filter, it is
range of 200 mls is started. conventionally controlled based on the air mass.
NOx sensors The monitoring function also differs in this way:
During normal operation a fault is detected when the
A dew point must be reached for effective operation
EGR ratio is above or below defined limits for a
and therefore also the monitoring of the NOx sensor. certain period of time. This applies to the air mass
This ensures that there is no longer any water in the during regeneration of the diesel particulate filter.
exhaust system that could damage the NOx sensors.
In order to monitor the high pressure EGR cooler, the
A reversible fault is set if the following temperature after the high pressure EGR cooler is
monitoring functions detect a fault at the NOx sensor. measured with the bypass valve open and close with
If the fault is determined in two successive driving the engine running at idle speed. A fault is detected if
cycles, an irreversible fault is stored and the MIL is the temperature difference is below a certain value.
activated. For the low pressure EGR cooler (only E70), the
• Detection signal or correction factorincorrect measured temperature after the low pressure EGR
cooler is compared with a calculate temperature for
• Line break or short-circuit betweenmeasuring this position. A fault is detected if the difference
probe and control unit of NOx sensor exceeds a certain value.

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Each of these faults is stored reversible. If the fault is
determined in two successive driving cycles, an
irreversible fault is stored and the MIL is activated.
Diesel particulate filter (DPF)
The diesel particulate filter is monitored by means of
the differential pressure sensor. If the filter is defective,
the differential pressure before and after the filter will
be lower than for a new filter.
Monitoringstartswhentheflowofexhaustgas and the
diesel particulate filter temperature exceed certain
values. A fault is detected when the differential
pressure drops below a defined threshold for a
certain period of time.
Conversely, an overloaded/clogged diesel particulate
filter is detected when the differential pressure
exceeds a defined value for a certain period of time.
When regeneration of the diesel particulate filter is
started, the time required until the
exhaust temperature before the DPF reaches 250 °C
is measured. This time is set to zero if
the engine runs for a longer period of time at idle
speed or in overrun mode. A fault is detected if a
defined time is exceeded before the temperature of
250 °C is reached. In this way, the response
characteristics of the increase in exhaust temperature
for DPF regeneration are monitored.
The system also monitors whether the exhaust gas
temperature before the diesel particulate filter
corresponds to the expected
valueafteradefinedperiodoftime.Ifthisisnot the case
although the control system has reached its limits, a
fault is detected.
Also in this case, each of these faults is stored
reversible. If the fault is determined in two successive
driving cycles, an irreversible fault is stored and the
MIL is activated.

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Automatic transmission
In view of the high torque developed by the gearbox is used, which is normally fitted in 8-
M57D30T2 engine, the GA6HP26TU cylinder petrol engine vehicles.

75 -GA6HP26TU gearbox

Twin damper torque converter

The gearbox is identical to that used in the X5 4.8i;
only the torque converter is different. A so-called
turbine torsional damper (TTD) is used while a twin
damper torque converter is used for diesel engines.
In principle, the twin damper torque converter is a
turbine torsional damper with a further damper
connected upstream.
The primary side of the first damper is connected to
the converter lockup clutch while the secondary side
is connected to the primary side of the second
damper. As in the turbine torsional damper, the
secondary side is fixed to the turbine wheel of the
torque converter.

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76 - Twin damper torque converter

Index Explanation Index Explanation

1 Annular spring 5 Stator
2 Converter housing 6 Transmission input shaft
3 Turbine wheel 7 Annular spring assembly
4 Impeller

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When the converter lockup clutch is open, the power
flow is equal to that of the turbine torsional damper.
The power is transferred from the turbine wheel via the
second damper
(but without damping) to the transmission input shaft.
When the converter lockup clutch is closed, the
power is transmitted via the first damper that consists
of an annular spring. From here the power is
transmitted to the second damper which
operationally corresponds to the turbine torsional
damper and also consists of two annular springs.
These further improved damping properties
effectively adapt the transmission to the operational
irregularities of the diesel engine.

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