N42 Engine

Course Contents/Background Material

Information status:
12/2000

VS-20 Gernot Nehmeyer

NOTE
The information contained in this training course manual is intended solely for
the participants of the BMW Service Training course.
Refer to the relevant "Technical Service" information for any
changes/supplements to the Technical Data.

© 2000 BMW AG
München, Germany. Reprints of this manual or its parts
require the written approval of BMW AG, München
VS-42 MFP-HGK-N42
N42 Engine Chapter 1-6

Course contents/Background material

Contents
Page

CHAP 1 N42 engine 3

Introduction 3
New engine generation NG4 8

CHAP 2 N42: notes on documents 14

N42 engine mechanical system 14
Intake system 14
Crankcase ventilation 14
Alternator 14
Characteristic map thermostat 14
Oil pan seal 14
Counterbalance shafts 14
Assembled crankshaft bearing 14
Oil-to-water heat exchanger 14
N42 engine management 15
General 15
Variable-geometry intake system 15
N42 fuel system 15
Mixture control 15
Fuel tank ventilation 15
N42 clutch 15
Self-adjusting clutch (SAC) 15

CHAP 3 N42 engine mechanical system 16

Air ducts 16
Fresh air system 16
Intake silencer with air cleaner 17
Intake system 17
Crankcase ventilation system 20
Exhaust system 21
Ancillary components and belt drive 23
Cylinder head 28
Cooling system 54
Engine block 60
Lubrication system 68
Service notes 74

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N42 Engine Chapter 1-6

Course contents/Background material

CHAP 4 N42 engine management 75

New features ME 9.2 75
Introduction 75
Overview ME 9.2 76
Components 82
Functional description ME 9.2 84
VANOS 84
Secondary air system 85
Emission control 86
Ambient pressure sensor 89
Intake pipe pressure sensor 89
Valvetronic 91
General 91
Eccentric shaft sensor 93
Electric motor for eccentric shaft adjustment 94
Functional description Valvetronic 95
Eccentric shaft sensor 95
Electric motor for eccentric shaft adjustment 98
Valvetronic control unit 99
Idle speed control 100

CHAP 5 N42 fuel system 101

Mixture control 101
Fuel tank ventilation 101

CHAP 6 N42 clutch

SAC - Self adjusting clutch 103
Introduction 103
Notes on maintenance and repair 104

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N42 Engine Chapter 1 P.1

Course Contents/Background Material

N42 engine
Introduction

History

Today's turbocharged diesel engines with direct fuel injection

are true hightech powerplants. With these engines it has been
possible to further reduce fuel consumption while making
inroads into performance ranges which, to date, were the
reserve of the petrol engine.
In the past years development of the petrol engine has achieved
a high performance level, a fuel reduction of 10% while, at the
same time, achieving no increase in emissions. Instruments in
achieving these objectives include 4-valve technology, friction-
optimized valve timing gear, camshaft adjustment (VANOS),
intake pipe injection and electronic engine management.
Nevertheless, in the meantime, a noticeable gap has developed
with regard to fuel consumption between the petrol engine and
diesel engine. Concepts such as direct fuel injection and
throttle-free load control with fully variable valve timing gear
exhibits such a potential in the petrol engine that they are
approaching the partial load fuel consumption values of modern
diesel engines.

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N42 Engine Chapter 1 P.2

Course Contents/Background Material

Future

The objectives for the future include the following customer and
legislative requirements:
- Reduced fuel consumption
- Improved performance
- Increased comfort
- Reduced emissions
- Improved cost/benefit ratio

By analyzing the development of the specific fuel consumption

(fuel consumption in gram to achieve an output of one kilowatt
hour) of petrol engines at a defined operating point a wide
scatter range can be determined at approx. 400 g/kWh. The
best values of modern engines are expected to be found at
approx. 385 g/kWh. Improvements of 10% have been achieved
in the last 15 years in this scatter range. Refer to the following
diagram.

Petrol engines

g/kWh
Chamber diesel

DI diesel

Year
KT-6297
Fig. 1: Consumption diagram
valid for partial load operating point 2000 rpm and 0.2 kJ/dm3

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N42 Engine Chapter 1 P.3

Course Contents/Background Material

Refered to the engine, improvements in fuel consumption mean

an increase in efficiency. There are three technically feasible
options for increasing efficiency:
- Increasing the efficiency of the engine
(e.g. direct injection with air surplus, variable compression
ratio, etc.)
- Reduction of losses attributed to frictional work
(e.g. better oils, roller-type fingers, etc.)
- Avoidance of charge cycle losses
(e.g. fully variable valve timing gear)

Of these three options, avoiding charge cycle losses represents

the greatest improvement potential and, in principle, can be
used on any throttle-controlled engine.

VANOS Valvetronic Petrol-DI

(direct injection)

High pressure efficiency + + ++

Charge cycle work o ++ ++

Emission characteristic + + -

Full load + + +(+)

++ = very good; + = good; o = normal; - = poor

Throttle-free load control with fully variable valve timing gear

represents a potential for reducing fuel consumption
approaching that of the petrol engine with direct injection
without having to make allowances for any weak points in the
functional principle.
At BMW, the fully variable valve timing gear is referred to as
Valvetronic.
Valvetronic allows for a significant improvement in fuel
consumption without the disadvantages of direct injection with
regard to the exhaust emission characteristics.

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N42 Engine Chapter 1 P.4

Course Contents/Background Material

The principle

Gain Gain

Loss
Loss

KT-6299 KT-6298

Fig. 2: Charge cycle diagram comparison - left without Valvetronic, right with
Valvetronic

Index Explanation Index Explanation

P Pressure AÖ Exhaust valve opens

OT Top dead centre AS Exhaust valve closes

UT Bottom dead centre Z Ignition timing

EÖ Intake valve opens 1 Work output

ES Intake valve closes 2 Compression output

The upper area designated "gain" represents the gained output

during the combustion of fuel. The lower area designated "loss"
represents the charge cycle work. This is the energy that must
be applied in order to expel the combusted exhaust gases from
the cylinder and to draw the fresh gases into the cylinder.
The throttle valve is almost always fully opened during intake in
the Valvetronic engine. Load control is based on the moment the
valve closes. Compared to the standard engine which is load-
controlled by means of the throttle valve, no vacuum occurs in
the intake system, i.e. the energy used for generating the
vacuum is no longer required.

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N42 Engine Chapter 1 P.5

Course Contents/Background Material

The improved efficiency is achieved by the lower power loss

during the intake operation.
In the previous diagram, the conventional procedure with the
slightly greater loss is shown on the left.
The reduced loss can be clearly seen in the right-hand diagram.
Differing from the diesel engine, in the case of the conventional
petrol engine, the volume of intake air is controlled by means
of the accelerator pedal and the throttle valve and the
corresponding volume of fuel is injected in the stoichiometric
ratio (λ=1).
In contrast to direct fuel injection with layer-type cylinder charge,
the air volume is controlled in the Valvetronic system thus
realizing λ=1 operation.
This renders unnecessary an expensive DeNOx catalytic
converter which is also susceptible to sulphur. Worldwide use
is possible (also in the USA with fuel containing sulphur).
DeNOx is the designation for the catalytic reduction of nitrogen
oxides.
This reduction is achieved in two different ways.
1. Buffer catalytic converter method:
A catalytic converter is installed which is capable of buffering
NOx components. The engine must then be operated for
a short period in "rich" setting in order to break down the
NOx components. The catalytic converter is coated with
vanadium and platinum.
2. Continuous method:
A catalytic converter is installed which is coated with iridium. To
facilitate continuous conversion, the catalytic converter also
contains urea. The iridium and urea now facilitate continuous
breakdown of the NOx components.

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N42 Engine Chapter 1 P.6

Course Contents/Background Material

New engine generation NG4

NG4 engine family

The new engine generation NG4 will gradually replace the

M43TU engine. The N42 engine is the founding member of the
new 4-cylinder engine family and is a completely new
development. A fully variable valve timing gear, i.e. Valvetronic,
will be introduced for the first time with this engine family.
The name Valvetronic refers to a system with which the valve
timing and the valve lift of the intake valve are set variable.

Engine Special feature

N42B18 Engine with Valvetronic (double VANOS and valve lift adjustment)
N42B20 Engine with Valvetronic (double VANOS and valve lift adjustment)
and DISA

The following table shows the phase-in dates of the N42 engine
in the respective models:

Model Engine Planned phase-in

316ti E46/5 N42B18 04/01
316i E46/4/3 N42B18 03/02
318i E46/2/3/4/C N42B20 09/01
318ti E46/5 N42B20 03/02

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N42 Engine Chapter 1 P.7

Course Contents/Background Material

Technical data

Engine N42B18 N42B20

Engine type 4-cyl. in-line 4-cyl. in-line

Displacement (cm3) 1796 1995

Bore/stroke (mm) 84/81 84/90

Cylinder spacing (mm) 91 91

Main bearing Ø of crankshaft (mm) 4 x 56 4 x 56

1 x 65 1 x 65

Big-end bearing Ø of crankshaft (mm) 50 50

Output (kW) 85 105

at engine speed (rpm) 5500 6000

Torque (Nm) 175 200

at engine speed (rpm) 3750 3750

Cutoff speed (rpm) 6500 6500

Compression ratio 10.2 10.0

Valves/cylinder 4 4

Intake valve Ø (mm) 32 32

Exhaust valve Ø (mm) 29 29

Intake valve lift (mm) 0.3 - 9.7 0.3 - 9.7

Exhaust valve lift (mm) 9.7 9.7

Camshaft opening angle I/E (º) 250/258 250/258

Camshaft spread I/E (º) 60-120/60-120 60-120/60-120

Engine weight (kg) (UFG 11 to 13) 120 120

Fuel system (RON) 98 98

Fuel (RON) 91-98 91-98

Knock control Yes Yes

Variable-geometry intake system (DISA) No Yes

Digital motor electronics ME9.2 + ME9.2 +

Valvetronic Valvetronic
control unit control unit

Emission regulation Germany EU3/D4 EU3/D4

Other countries EU3 EU3

Engine length (mm) 490 490

Reduction in fuel consumption compared to 12% 12%

M43TU

Vmax (km/h) E46/5 (provisional) 201 213

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N42 Engine Chapter 1 P.8

Course Contents/Background Material

Full load diagrams

N42B18
Output in kW

Torque in Nm

Engine speed rpm

KT-6611

Fig. 3: Full load diagram N42B18

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N42 Engine Chapter 1 P.9

Course Contents/Background Material

N42B20
Output in kW

Torque in Nm

Engine speed rpm

KT-6677

Fig. 4: Full load diagram N42B20, provisional

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N42 Engine Chapter 1 P.10

Course Contents/Background Material

Views of N42B18 engine

KT-6385
Fig. 5: N42 engine

KT-6383
Fig. 6: N42 engine

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N42 Engine Chapter 1 P.11

Course Contents/Background Material

KT-6384
Fig. 7: N42 engine

KT-6386
Fig. 8: N42 engine

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N42 Engine Chapter 2 P.1

Course Contents/Background Material

N42: notes on documents

N42 engine mechanical system
Intake system
For fundamental information on the DISA see M43TU

Crankcase ventilation
For function of the pressure control valve see M44

Alternator
For functional principle see M57 EU3

Characteristic map thermostat

For function of the characteristic map thermostat see M43TU

Oil pan seal

For design and function of the oil pan seal see M54

Counterbalance shafts
For function of counterbalance shafts see M43TU

Assembled crankshaft bearing

For design of assembled crankshaft bearing see M43TU

Oil-to-water heat exchanger

For design and function see M43TU

© BMW AG, Service Training

N42 Engine Chapter 2 P.2

Course Contents/Background Material

N42 engine management

General
For functions and components known from the BMW petrol
engines, see BMW petrol engine management Part 1 and Part 2
as well as M54.

Variable-geometry intake system

For functional principle of the DISA see M44, M42, M43

N42 fuel system

Mixture control
For design and function see E46 M54

Fuel tank ventilation

For design and function see E46

N42 clutch
Self-adjusting clutch (SAC)
For design and function see self-adjusting clutch

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N42 Engine Chapter 3 P.1

Course Contents/Background Material

N42 engine mechanical system

Air ducts
Fresh air system
The complete fresh air system has been newly designed. The
two figures below show the air ducts up to the intake manifold.

KT-6690

Fig. 1: Top view of fresh air duct (arrow = air cleaner housing)

KT-6691

Fig. 2: Bottom view of fresh air duct (arrow = air cleaner housing), resonator (circle)

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N42 Engine Chapter 3 P.2

Course Contents/Background Material

Intake silencer with air cleaner

The intake system has been newly designed with the aim of
reducing the intake noise and facilitating ease of servicing.
The volume of the air cleaner housing is 9.4 l. The air cleaner
itself has a volume of 1.9 l and is designed as a round filter,
allowing for a service life of approx. 100,000 km. The entire air
cleaner must be removed in order to change it.
A gaiter is fitted between the air cleaner and the throttle valve.
An acoustic resonator is mounted on the gaiter. The resonator is
designed as an empty plastic housing. Its task is to reduce
intake noise in a defined vibration range. The resonator can be
seen in the previous picture (in the circle) located beneath the air
cleaner housing.

Intake system

KT-6385

Fig. 3: N42 engine

The intake system of the N42B18 is made completely of plastic

and, compared to the M43TU engine, it is designed as a single
component.

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N42 Engine Chapter 3 P.3

Course Contents/Background Material

DISA

The N42B20 engine is equipped with the variable-geometry

intake system (DISA) in order to achieve a robust torque
progression already at low engine speeds without having to
accept losses in engine output in the higher speed ranges.
For this purpose, the self-charging principle can be utilized in
the lower speed range while higher output values are achieved
in the upper engine speed range by switching over to the shorter
intake path.
The function of the DISA of the N42B20 is comparable with that
of the DISA of the M43TU. In the N42B20 engine, the function of
the DISA is realized by one sliding sleeve per cylinder.
Adjustment of the sliding sleeves is controlled by the DME with a
12 V electric motor with integrated gear mechanism. The DME
determines whether a shift up or down has been output.

1
2 3

KT-6770

Fig. 4: DISA sectional view, short intake path (yellow arrow), long intake path
(red arrow)

Index Explanation Index Explanation

1 Sliding sleeve 3 Throttle valve connection
2 Electric motor 4 Intake system

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N42 Engine Chapter 3 P.4

Course Contents/Background Material

The changeover to the short intake path takes place speed-

dependent at 4500 rpm. The return to the long intake path takes
place delayed at approx. 4400 rpm in order to avoid the DISA
overshooting in the switching range.
The position of the sliding sleeves can be viewed through the
opening in the throttle valve.
In the event of the DISA failing, the system stops in the
respective position. For the driver, such a failure may mean loss
of power and reduced top speed.
After turning off the engine (terminal 15 off), the system is moved
once to the extreme stop positions for the purpose of avoiding
deposits and sticking of the sliding sleeves during longer driving
periods at low engine speeds.

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N42 Engine Chapter 3 P.5

Course Contents/Background Material

Crankcase ventilation system

1
3

2
KT-6399
Fig. 5: Crankcase ventilation system

Index Explanation Index Explanation

1 Breather hose 3 Cyclone oil separator
2 Condensation water return line 4 Pressure control valve

The N42 engine features a pressure-controlled crankcase

ventilation system. The crankcase gases at the cylinder head
cover are routed via a plastic hose (1) to the cyclone oil
separator (3). The cyclone oil separator is mounted between the
engine block/cylinder head and the intake system. The conden-
sation water separated at this point flows via the condensation
water return line (2) to a connection at the oil dipstick and via
this back into the oil pan. The remaining gases are fed via the
pressure control valve (4) into the intake system to the engine for
combustion.
The throttle valve is controlled such that there is always a
vacuum of 50 mbar in the intake system.
The pressure control valve regulates a vacuum of 20 mbar
±20 mbar in the crankcase.
Refer to the document M44 engine for a description of the
function of the pressure control valve.

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N42 Engine Chapter 3 P.6

Course Contents/Background Material

Exhaust system

System overview

1 2 3 4 5 6 7
KT-6722

Fig. 6: Exhaust system E46/4

1 2 3 4 5 6 7
KT-6723

Fig. 7: Exhaust system E46/5

Index Explanation Index Explanation

1 2 planar (flat sensors) 5 1 monitor oxygen sensor
wideband oxygen sensors
2 1 monitor oxygen sensor 6 Centre silencer
3 Preliminary catalytic 7 Rear silencer
converters
4 Main catalytic converter

The exhaust system has been newly designed for the N42B18
and N42B20 engines and is identical for both engines.
The exhaust system consists of the exhaust manifold, two metal
carrier preliminary catalytic converters, one main catalytic
converter, one centre silencer and the rear silencer.

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N42 Engine Chapter 3 P.7

Course Contents/Background Material

Exhaust manifold with catalytic converter

A four in two manifold with two planar (flat sensor elements)

Bosch wideband oxygen sensors (designation LSU 4.2), two
metal carrier preliminary catalytic converters, one monitor
oxygen sensor after the main catalytic converter (designation
LSU 25) as well as one monitor oxygen sensor after the
preliminary catalytic converter (designation LSU 25) are
installed.

Centre silencer and rear silencer

The centre silencer is designed in accordance with the

adsorption principle and has a volume of 7.3 l.
The rear silencer represents a combination of reflection and
absorption system and has a volume of approx. 19 l.
Reflection involves the reflection of sound waves on solid
surfaces, e.g. inlet and outlet of the silencer pipe are offset in
the silencer.
Absorption involves the absorption of sound waves, e.g. use of
steel wool in order to "swallow" the sound waves.

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N42 Engine Chapter 3 P.8

Course Contents/Background Material

Ancillary components and belt drive

Belt drive

8 5
7
6

KT-6386
Fig. 8: Belt drive

Index Explanation Index Explanation

1 Alternator belt pulley 5 Belt progression without A/C
compressor
2 Deflection pulley 6 Belt progression with A/C
compressor
3 Belt tensioner 7 Crankshaft vibration absorber
4 A/C compressor belt pulley 8 Power steering pump and water pump
belt pulley

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N42 Engine Chapter 3 P.9

Course Contents/Background Material

KT-6410

Fig. 9: Belt tensioner in installed position with retaining pin (arrow)

The belt tensioner is new. A strong coil spring undertakes the

belt tensioning function. A cone is responsible for damping by
means of friction. The belt tensioner is secured by means of a
central screw to the engine block.

Vibration absorber

KT-6386

Fig. 10: Vibration absorber

The torsional vibration absorber is secured by means of three

screws on the hub of the crankshaft.

© BMW AG, Service Training

N42 Engine Chapter 3 P.10

Course Contents/Background Material

Alternator

The alternator is mounted on the left-hand side of the engine. A

new generation of alternators is used. The functional principle of
this alternator is known from the diesel engines.
It has been necessary to modify the regulator of the alternator
due to the implementation of the Valvetronic system. Since the
actuator of the Valvetronic system has a very high power intake
during start-up, the task of the alternator regulator is to very
quickly compensate for these fluctuations occurring in the
vehicle electrical system. If the old regulator were still used,
there would be a noticeable difference in the brightness of the
lighting while driving at night.
The new generation of regulators is now even faster. This rapid
control is only possible outside the load response function.
The general module and the light switch centre have also been
modified to ensure the vehicle lighting does not flicker.
Two different power stages of alternators are fitted. The
manufacturers of the new generation of alternators are Bosch
and Valeo. A 90 A alternator is installed as standard. A 120 A
alternator is fitted when the vehicle is equipped with automatic
transmission and air conditioning or manual transmission with
seat heating.
Regulator

KT-6675

Fig. 11: Circuit diagram of 90 A alternator

Index Explanation Index Explanation

G1 Alternator S1 Ignition/starter switch
DME Engine control unit B1 Battery
L1 Battery charge indicator lamp BSD Bit-serial data interface

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N42 Engine Chapter 3 P.11

Course Contents/Background Material

The data exchange between the DME and alternator takes place
via the BSD (bit-serial data interface) thus making it possible to
almost completely compensate the load torque at idle speed.
The idle speed control is thus correspondingly supported and
the charge level can be improved by intervention of the engine
management.
Refer to Section "Engine management, idle speed control" for
further information.

Power steering pump

KT-6435

Fig. 12: Power steering pump on right-hand side of engine

The power steering pump is mounted on the right-hand side of

the engine thus rendering it necessary to correspondingly adapt
the power steering lines to the new conditions. The engine has
also been designed for transverse installation.

A/C compressor

The A/C compressor is mounted on the left-hand side of the

engine thus rendering it necessary to rearrange the lines in the
air conditioning system. The new type of A/C compressor is
manufactured by Calsonik.

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N42 Engine Chapter 3 P.12

Course Contents/Background Material

Starter

KT-6401
Fig. 13: Starter

The starter is located under the intake manifold which must be

removed in order to replace the starter.
The starter is designed as a compact reduction gear starter with
an output of 1.4 kW.

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N42 Engine Chapter 3 P.13

Course Contents/Background Material

Cylinder head

Ignition coil cover

KT-6674

Fig. 14: Ignition coil cover

The ignition coil cover encompasses the ignition lead wiring

loom, the rod-type ignition coils and the actuator for the
eccentric shaft.

Cylinder head cover

KT-6422
Fig. 15: Cylinder head cover

The cylinder head cover is made of plastic. The sleeves (arrow)

for the rod-type ignition coils are fitted in the cylinder head as
well as in the cylinder head cover and sealed with O-rings.

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N42 Engine Chapter 3 P.14

Course Contents/Background Material

Fully variable valve timing gear

The valve timing gear is a new BMW development.

For the first time, a fully variable valve timing gear system,
Valvetronic, is used in automotive engineering.
Function:
The need to draw in air against a partially closed throttle valve
uses up fuel particularly in the partial load range.
Valvetronic is a system which, together with the VANOS and a
valve lift adjustment system, can facilitate fully variable control
of the intake valves. With the throttle valve fully opened, the air
volume is controlled by the valve lift and the VANOS. The valve
lift control is realized by means of an intermediate lever (6)
between the camshaft (4), roller-type finger (9) and eccentric
shaft (5). The required gear ratio is adjusted by means of the
eccentric shaft (5) and the intermediate lever (6). The eccentric
shaft (5) is operated by a worm gear drive powered by an
electric motor. The DME stipulates the setpoint and the
Valvetronic correspondingly sets this setpoint. Feedback is
provided by the eccentric shaft sensor.

KT-6442
Fig. 16: N42 valve timing gear

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N42 Engine Chapter 3 P.15

Course Contents/Background Material

7 6
4

KT-6733

Fig. 17: Graphic representation of valve lift adjustment

Index Explanation Index Explanation

4 Intake camshaft 7 Retaining spring for intermediate
lever
5 Eccentric shaft 9 Roller-type finger
6 Intermediate lever

KT-6405
Fig. 18: Intake (E) and exhaust camshaft (A)

The exhaust camshaft features round recesses (arrows). They

serve the purpose of providing access to the cylinder head bolt.
It is possible to disassemble the cylinder head without removing
the camshafts.

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N42 Engine Chapter 3 P.16

Course Contents/Background Material

Double VANOS (variable camshaft control)

The N42 engine features a new, compact, infinitely variable

vane-type VANOS for the intake and exhaust sides. The VANOS
unit is easy to disassemble and install. The VANOS unit is
designed as an integrated component of the chain drive and is
secured to the respective camshaft with a central bolt.
Setting the valve timing has become greatly simplified with the
new VANOS unit as it is locked in the basic setting by means of
a locking pin when no pressure is applied. It is, however,
important that the repair instructions are followed exactly. The
VANOS unit can no longer be dismantled.

1
3
4
2

KT-6421

Fig. 19: Position sensor and VANOS solenoid valves

Index Explanation Index Explanation

1 Solenoid valve, exhaust 3 Exhaust camshaft sensor
VANOS
2 Solenoid valve, intake VANOS 4 Intake camshaft sensor

KT-6388

Fig. 20: VANOS unit on the exhaust side

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N42 Engine Chapter 3 P.17

Course Contents/Background Material

KT-6418
Fig. 21: VANOS with sensor gearwheels and mounting screws

KT-6419

Fig. 22: VANOS on intake side with marking

The letters "EIN IN" can be clearly seen in the figure above. The
VANOS units on the intake and exhaust sides differ and are
identified by this marking. The designation "AUS OUT" is
provided on the VANOS unit for the exhaust side.
When replacing components, particular attention must be
paid to the part number as, in future, engines will feature
VANOS units which can only be differentiated visibly by
the part number. Installing the incorrect VANOS unit can
cause serious engine damage.

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N42 Engine Chapter 3 P.18

Course Contents/Background Material

13 11

12

KT-6404
Fig. 23: Camshaft with VANOS supply holes

KT-6468

Fig. 24: Sectional view through the camshaft at the VANOS connection

Index Explanation Index Explanation

11 Pressure channel A 13 Hook seal
12 Pressure channel B

The hook seal (13) is important for the oil supply of the VANOS
unit. The seal must be installed to ensure effective VANOS
operation. The hook seal (plastic ring) is designed as an open
O-ring with hooks on both ends that engage in each other.

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N42 Engine Chapter 3 P.19

Course Contents/Background Material

The VANOS solenoid valve is a 4/3-way proportional valve.

The solenoid valve is mounted in the cylinder head and
connected via channels in the cylinder head to the camshaft and
the VANOS unit. The oil galleries pass through the cylinder head
and the camshaft.

KT-6420

Fig. 25: VANOS solenoid valve

The solenoid valve is sealed off by means of O-rings (see arrow).

The solenoid valve is secured on the cylinder head with the aid
of retaining plates (pressed against the cylinder head with a
minimum force of 300 N). The retaining plates must not be
deformed. Follow the repair instructions precisely.

© BMW AG, Service Training

N42 Engine Chapter 3 P.20

Course Contents/Background Material

The figure below shows the adjustment procedure together with

the pressure progression based on the example of the VANOS
unit for the exhaust side.

9
3
8 8 8

1 2
10
4

7
5
KT-6509

Fig. 26: System diagram of VANOS adjustment on exhaust side

Index Explanation Index Explanation

1 Top view of VANOS unit 6 Engine oil from oil pump
2 Side view of VANOS unit 7 Engine oil from oil pump
3 Hole for hydraulics in 8 Pressure channel A
camshaft, pressure channel B
4 Solenoid valve 9 Pressure channel B
5 Oil pump, engine 10 Reservoir return in cylinder head

The oil from the solenoid valve returns into a reservoir. This
reservoir is designed as an oil duct in the cylinder head leading
upward into the camshaft chamber.

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N42 Engine Chapter 3 P.21

Course Contents/Background Material

9
3
8 8 8

1 2
10
4

7
5

KT-6508

Fig. 27: System diagram of VANOS reset on exhaust side

Index Explanation Index Explanation

1 Top view of VANOS unit 6 Engine oil return in cylinder head
2 Side view of VANOS unit 7 Engine oil pressure from oil
pump
3 Hole for hydraulics in 8 Pressure channel A
camshaft
4 Solenoid valve 9 Pressure channel B
5 Oil pump, engine 10 Reservoir return in cylinder head

© BMW AG, Service Training

N42 Engine Chapter 3 P.22

Course Contents/Background Material

KT-6456 KT-6459

Fig. 28: Sectional view through the VANOS unit

Index Explanation Index Explanation

1 Housing with crown gear 7 Rotor
2 Front plate 8 Back plate
3 Torsion spring 9 Blade
4 Lock spring 10 Spring
5 Retaining plate for lock spring 11 Pressure channel A
6 Locking pin 12 Pressure channel B

The figure above shows a sectional view of the VANOS unit. The
rotor (7) is screw-mounted on the camshaft.
The timing chain connects the crankshaft with the housing of the
VANOS unit (1). Springs (10) which press the blades (9) against
the housing are fitted on the rotor (7). There is a recess in
rotor (7) in which the locking pin (6) engages without pressure
being applied. If the solenoid valve now switches the oil
pressure to the VANOS unit, the locking pin (6) is pressed back
thus releasing the VANOS for adjustment. The applied engine oil
pressure in pressure channel A (11) now presses the blade (9)
and thus the rotor (7) into another position thus adjusting the
timing as the camshaft is screwed to the rotor.
As the VANOS solenoid valve switches over, the oil pressure
applied in pressure channel B (12) moves the rotor (7) back into
the initial position. The torsion spring (3) acts against the
camshaft torque.

© BMW AG, Service Training

N42 Engine Chapter 3 P.23

Course Contents/Background Material

Crankshaft

TDC BDC TDC BDC TDC

Normal position Normal position

Intake VANOS Exhaust VANOS
Maximum adjustment Maximum adjustment
Intake VANOS Exhaust VANOS
KT-6450

Fig. 29: N42 timing diagram

© BMW AG, Service Training

N42 Engine Chapter 3 P.24

Course Contents/Background Material

Valve lift adjustment

The valve lift control is realized by means of an intermediate

lever (6) between the camshaft (4), roller-type finger (9) and
eccentric shaft (5). The required gear ratio is adjusted by means
of the eccentric shaft (5) and the intermediate lever (6). The
eccentric shaft (5) is operated by a worm gear drive powered by
an electric motor.

7 6
4

KT-6733

Fig. 30: Graphic representation of valve lift adjustment

Index Explanation Index Explanation

4 Intake camshaft 7 Retaining spring for intermediate
lever
5 Eccentric shaft 9 Roller-type finger
6 Intermediate lever

© BMW AG, Service Training

N42 Engine Chapter 3 P.25

Course Contents/Background Material

The drive of the valve lift control is provided by an electric motor.

The eccentric shaft is turned by a worm gear unit.

KT-6402
Fig. 31: Electric motor for adjusting the eccentric shaft

KT-6432

Fig. 32: Eccentric shaft

KT-6426

Fig. 33: Drive of eccentric shaft (worm gear drive)

© BMW AG, Service Training

N42 Engine Chapter 3 P.26

Course Contents/Background Material

7
5
8

6 4
2

KT-6442
Fig. 34: Top view of cylinder head

Index Explanation Index Explanation

1 VANOS unit on the exhaust 5 Eccentric shaft
side
2 VANOS unit intake side 6 Intermediate lever
3 Exhaust camshaft 7 Retaining spring for intermediate
lever
4 Intake camshaft 8 Eccentric shaft sensor

5
4
6

KT-6427

Fig. 35: Top side view of timing gear

© BMW AG, Service Training

N42 Engine Chapter 3 P.27

Course Contents/Background Material

Uniform distribution must be ensured as the minimum valve lift

at idle speed is only 0.3 mm. All valves must be opened wide to
the same extent. The maximum deviation of the opening stroke
may only be ±10%.
For this reason, the roller-type fingers and the intermediate
levers are divided into four classes. The classification is marked
by means of laser on the components. The components are
subject to precision measurement in order to be able to classify
them.
Specific allocation of the roller-type fingers and of the
intermediate levers ensures that all valves open wide simulta-
neously. The idle lift of the valves is additionally measured at the
factory.
A matching pair of roller-type fingers is installed as required.
This pair of roller-type fingers may deviate with regard to the
classification from the other installed roller-type fingers.

KT-6424
Fig. 36: Intermediate lever (6) and roller-type finger
The intermediate lever transmits the cam movement to the roller-type finger
dependent on the setting of the eccentric shaft.

KT-6425
Fig. 37: Intermediate lever (6) and roller-type finger

CAUTION:
Particular care must be taken when disassembling the valve
timing gear to ensure that all intermediate levers and roller-type
fingers are marked so that they are reinstalled in the correct
position during reassembly.
Disregard of this requirement can cause uneven distribution of
the cylinder charge.
Irregular opening of the valves results in irregular, rough idle
speed.

© BMW AG, Service Training

N42 Engine Chapter 3 P.28

Course Contents/Background Material

5 7

KT-6433

Fig. 38: Rear top view of the valve timing gear (roller-type finger (9))

KT-6394

Fig. 39: Retaining spring for intermediate lever (7)

The retaining spring presses the intermediate lever against the eccentric
shaft, the camshaft and the roller-type finger.

© BMW AG, Service Training

N42 Engine Chapter 3 P.29

Course Contents/Background Material

10

KT-6393

Fig. 40: Torque compensation spring (10) for eccentric shaft

Index Explanation Index Explanation

4 Intake camshaft 10 Torque compensation spring
5 Eccentric shaft

10

KT-6392

Fig. 41: Torque compensation spring (10) for eccentric shaft

The torque compensation spring (10) facilitates electric motor

adjustment of the eccentric shaft.

© BMW AG, Service Training

N42 Engine Chapter 3 P.30

Course Contents/Background Material

5
5

10
10
KT-6823

Fig. 42: Functional principle of the torque compensation spring

Index Explanation Index Explanation

FF Spring force h Lever arm of eccentric shaft
MF Torque on eccentric shaft 5 Eccentric shaft
10 Torque compensation spring

In the left-hand diagram, the torque is very low since there is

only a very low or no lever arm for transmitting the spring force
FF.
In the right-hand diagram, the spring force FF acts on the
eccentric shaft 5 over the lever travel h thus generating the
torque MF.

© BMW AG, Service Training

N42 Engine Chapter 3 P.31

Course Contents/Background Material

11 5

KT-6428

Fig. 43: Magnetic wheel (11) on eccentric shaft (5)

Powerful magnets are fitted in the magnetic wheel (11) of the

eccentric shaft (5). Together with the eccentric shaft sensor (8)
these magnets serve the purpose of determining the exact
position of the eccentric shaft (5). The magnetic wheel is
secured to the eccentric shaft by means of a non-magnetic
special steel screw. On no account should a magnetic screw be
used otherwise the eccentric shaft sensor would supply
incorrect values.

KT-6429
Fig. 44: Cam carrier

The cam carrier serves as a guide for the intake camshaft and
eccentric shaft. The cam carrier also accepts the electric motor
for the valve lift control. The cam carrier is paired with the
cylinder head and must not be replaced individually.

© BMW AG, Service Training

N42 Engine Chapter 3 P.32

Course Contents/Background Material

variable

variable
variable
Crankshaft

TDC BDC TDC

Retard setting intake Intake VANOS adjusted variably

VANOS, max. valve lift Valve lift adjusted variably

Advance setting intake Intake VANOS adjusted variably

VANOS, max. valve lift Valve lift adjusted variably

Intake VANOS adjusted variably

Valve lift minimum
KT-6743

Fig. 45: Valve lift control diagram with intake VANOS adjustment

The figure above shows the VANOS adjustment facility. The valve
lift adjustment facility has been additionally incorporated in the
graphic.
The special feature of the Valvetronic is that the air mass drawn
in can be freely determined by the closing time of the valve and
the valve lift.
The air mass in the cylinder is thus limited, thus the term load
control.
With the aid of VANOS, the closing point can be freely selected
within a defined range. With the valve lift control, the opening
duration and the cross section of the valve opening can also be
freely selected within a defined range.

© BMW AG, Service Training

N42 Engine Chapter 3 P.33

Course Contents/Background Material

Vacuum pump

Due to the introduction of the Valvetronic, the N42 engine

requires a vacuum pump for brake power assistance. Since the
throttle valve is open while driving, insufficient vacuum is built
up in the intake pipe for brake power assistance.
The vacuum pump is driven by the exhaust camshaft. The
delivered air is fed into the engine interior. The vacuum pump is
lubricated via an oil gallery in the cylinder head.

KT-6400

Fig. 46: Vacuum pump

KT-6413
Fig. 47: Vacuum pump (arrow = feed hole for lubrication)

© BMW AG, Service Training

N42 Engine Chapter 3 P.34

Course Contents/Background Material

The following figures show the design of the vacuum pump.

KT-6414 KT-6415

Fig. 48: Vacuum pump

1 2

KT-6416 KT-6417

Fig. 49: Vacuum pump disassembled

Index Explanation Index Explanation

1 Brake booster connection 2 Opening to cylinder head

© BMW AG, Service Training

N42 Engine Chapter 3 P.35

Course Contents/Background Material

Chain drive

The chain drive is completely new and based on a modular

design. The drive is divided into the chain drive module and the
oil pump drive module.

Chain drive module

1 1

2 3

6
4 5

10 6
9

11

8
KT-6670

Fig. 50: Chain drive module

Index Explanation Index Explanation

1 VANOS threaded connection 7 Chain pinion guide
2 VANOS sensor segment, exhaust 8 Chain pinion, camshaft
3 VANOS sensor segment, intake 9 Chain tensioner
4 VANOS exhaust 10 Chain tensioner seal
5 VANOS intake 11 Tensioning rail
6 Threaded connection for chain
drive

The seal for the chain tensioner must be replaced every time the
tensioner is loosened off.
The chain drive module is fitted in the timing case from above as
a sealed unit and secured with screws.

© BMW AG, Service Training

N42 Engine Chapter 3 P.36

Course Contents/Background Material

KT-6398

Fig. 51: Chain tensioner

The chain tensioner is new. The arrows in the figure above

indicate the punch marks on the banjo bolt on the chain
tensioner. These punched sections ensure the piston of the
chain tensioner is connected to the banjo bolt so that it moves.

Oil pump drive module

1
2

5
2 2
KT-6671

Fig. 52: Oil pump drive module

Index Explanation Index Explanation

1 Chain pinion for oil pump drive 4 Drive chain
2 Threaded connection 5 Oil pump sprocket
3 Chain tensioning rail

© BMW AG, Service Training

N42 Engine Chapter 3 P.37

Course Contents/Background Material

Cylinder head

The cylinder head is a new development. The timing case is cast

together with the cylinder head and no longer mounted by
threaded connections. The cylinder head is designed as a cross
flow head.

KT-6440
Fig. 53: Top view of cylinder head

KT-6441
Fig. 54: Bottom view of cylinder head

© BMW AG, Service Training

N42 Engine Chapter 3 P.38

Course Contents/Background Material

KT-6444
Fig. 55: Cylinder head bolts

Three different cylinder head bolts are fitted in the N42 engine.
The slightly shorter bolts are fitted in the front and rear areas.
The reason for this is to ensure the cylinder head gasket is
pressed down uniformly. Uniform pretension is achieved
between the cylinder head and engine block at all points due to
the different pretensioning forces of the various bolts. Follow the
repair instructions exactly during assembly and disassembly
(tightening torque, torquing angle and tightening
sequence).

Cylinder head gasket

KT-6443
Fig. 56: Cylinder head gasket

The cylinder head gasket is designed as a rubberized multi-layer

steel gasket. This gasket variant is already known from other
engines.

© BMW AG, Service Training

N42 Engine Chapter 3 P.39

Course Contents/Background Material

Cooling system

Coolant circuit

KT-6734

Fig. 57: Coolant circuit with IHKA

KT-6735

Fig. 58: Coolant circuit without air conditioning system

Index Explanation Index Explanation

1 Radiator 12 Heating heat exchanger
2 Electric fan, infinitely variable 13 Return, oil-to-water heat exchanger
3 Radiator supply hose 14 Heating supply hose (VL)
4 Radiator return hose 15 Heating return hose (RL)
5 Thermostat 16 Auxiliary water pump
6 Mechanical water pump 17 Supply, oil-to-water heat exchanger
7 Expansion tank 18 Heating valve
8 Hose between expansion tank 19 Transmission oil-to-water heat
and water pump exchanger
9 Bypass hose 20 Control cartridge
10 Double temperature sensor 21 Low temperature radiator
11 Fan temperature sensor

© BMW AG, Service Training

N42 Engine Chapter 3 P.40

Course Contents/Background Material

The bypass circuit (smaller coolant circuit) is not integrated in

the cylinder head but rather it is fed via a duct outside the
cylinder head. The coolant hoses are equipped with quick-
release couplings. The system pressure is 2.0 bar.
Section A-A
Cylinder head

Section B-B
Crankcase

Section C-C
Engine block

KT-6874

Fig. 59: Coolant circuit of N42 engine

Index Explanation Index Explanation

7 Expansion tank 19 Transmission oil-to-water heat
exchanger
10 Double temperature sensor 20 Control cartridge
12 Heating heat exchanger 21 Low temperature radiator
14 Heating supply hose 22 Bleeder screws
16 Auxiliary water pump 23 Oil-to-water heat exchanger
18 Heating valve 24 Level sensor

© BMW AG, Service Training

N42 Engine Chapter 3 P.41

Course Contents/Background Material

Water pump

The water pump is combined with the power steering pump. The
figure below shows the combination of the power steering
pump, water pump and thermostat.

2
1

3
KT-6395

Fig. 60: Water pump (1), power steering pump (2) and thermostat (3)

The combination is mounted on the right side of the engine and

is secured to the engine block by means of four screws.

KT-6434

Fig. 61: Water pump fitted in position

© BMW AG, Service Training

N42 Engine Chapter 3 P.42

Course Contents/Background Material

In the following figure, the connection flange between the water

pump and power steering pump can be seen at the top.

KT-6436

Fig. 62: Water pump with view of connection flange

KT-6437
Fig. 63: Water pump with view of pump wheel

The delivery capacity of the water pump is 7 m3/h.

A water pump is available for hot countries (hot country water
pump) with a delivery capacity of 10 m3/h.

© BMW AG, Service Training

N42 Engine Chapter 3 P.43

Course Contents/Background Material

Thermostat

The thermostat housing is connected by screws to the water

pump.

KT-6435
Fig. 64: Thermostat flanged on to water pump

KT-6411

Fig. 65: Thermostat

KT-6412

Fig. 66: Thermostat housing

© BMW AG, Service Training

N42 Engine Chapter 3 P.44

Course Contents/Background Material

Characteristic map thermostat

With the introduction of the N42B20 in 09/2001, a characteristic

map thermostat will also be introduced for the N42B18. The
maximum opening temperature is 105 ºC.
The characteristic map thermostat functions in the same way as
already known from the other engines (see M43TU). The use of
the characteristic map thermostat reduces fuel consumption by
approx. 1 - 2%.

Radiator

The radiator is identical to the radiator of the M43 engine.

The coolant expansion tank has been adopted from the
M52 engine.

Fan

A controlled electric fan is fitted. The electric fan has a sucking

action. Depending on the type, the electric fan has an output of
150 W or 390 W.

© BMW AG, Service Training

N42 Engine Chapter 3 P.45

Course Contents/Background Material

Engine block

Oil pan

The sheet steel oil pan is sealed off from the crankcase by
means of a rubberized sheet steel gasket. This type of gasket is
already known from the M54 engine.

Counterbalance shafts

The counterbalance shafts are similar to those in the M43TU

engine. The design has been correspondingly adapted for the
N42. The weight of the counterbalance shaft package has been
halved.
The counterbalance shaft housing is made of pressure die cast
aluminium. The drive is provided by the oil pump. The oil pump
in turn is driven via a separate chain by the crankshaft. This
chain is tensioned by a hydraulic chain tensioner.
Refer to the repair instructions for the installation sequence and
setting.

1 2
KT-6502
Fig. 67: Bottom view of engine

Index Explanation Index Explanation

1 Counterbalance shafts 2 Oil pump

© BMW AG, Service Training

N42 Engine Chapter 3 P.46

Course Contents/Background Material

Caution:
The counterbalance shaft housing is bolted to the oil pump. On
no account must these threaded connections be released as the
tooth backlash is set by means of this threaded connection and
this procedure should only be carried out at the factory.
The counterbalance shafts or the oil pump should only be
replaced as a common unit.

Crankcase

The two-piece crankcase is made completely of aluminium

(chilled casting). The parting point is in the centre of the
crankshaft bearings.
Cast iron cylinder liners are cast into the upper section of the
crankcase. The top of the cast iron cylinder liners are cast with
aluminium in order to ensure effective sealing with the cylinder
head gasket.
The crankcase can be reworked once. Pistons of repair stage 1
are available for this purpose.

3
2 1

KT-6403 KT-6835

Fig. 68: Sectional view of crankcase (right)

Index Explanation Index Explanation

1 Cast iron cylinder liner 2 3 Aluminium casting of crankcase
2 Cast iron cylinder liner 1

© BMW AG, Service Training

N42 Engine Chapter 3 P.47

Course Contents/Background Material

The bottom section of the crankcase is referred to as the

bedplate.

KT-6503
Fig. 69: Bottom section of crankcase (bedplate)

KT-6504
Fig. 70: Filler opening in upper section of crankcase for sealing compound between
upper section and lower section of crankcase

There is a groove in the lower section of the crankcase for

accepting the sealing compound via a special connection.
Since the crankshaft forces act on the threaded connection of
both parts of the crankcase it is important to ensure that this
connection is free of play. For this reason, the sealing compound
is applied after the threaded connections have been fitted.

© BMW AG, Service Training

N42 Engine Chapter 3 P.48

Course Contents/Background Material

1 3
4
2
KT-6697

KT-6696

Fig. 71: Crankshaft seal with sealing groove

Index Explanation Index Explanation

1 Upper section of crankcase 3 Seal
2 Bottom section of crankcase 4 Sealing compound

A repair kit containing sealing compound and a filler tool will be

available for repairs.
The graphic above shoes the position of the seal with respect to
the crankcase. The groove of the seal must be located at the
parting point of the upper section of the crankcase (1) to the
lower section of the crankcase (2) and the seal (3). During the
filling procedure, the sealing compound emerges from this
groove. It is important to make sure that sealing compound
emerges from all four grooves (seal at front and rear). Only in this
way is it possible to ensure that the crankcase is properly
sealed.

© BMW AG, Service Training

N42 Engine Chapter 3 P.49

Course Contents/Background Material

Crankshaft

The crankshaft of the N42 is a cast component. Axial mounting

is ensured by a 65 mm diameter built-in bearing (similar to the
M43TU) at the fifth bearing in the upper section of the
crankcase. Bearings 1 - 4 have a diameter of 56 mm.
Thanks to the larger thrust bearing it has been possible to
improve acoustics (counteracts flywheel sway).

4
6
1
7

3
KT-6672

Fig. 72: Crankshaft with bearings and incremental gearwheel

Index Explanation Index Explanation

1 Crankshaft 5 Lower bearing shell (5) ø 65 mm
2 Upper bearing shells (1-4) 6 Incremental gearwheel
ø 56 mm
3 Lower bearing shells (1-4) 7 Ball bearing for gear shaft
ø 56 mm
4 Upper thrust bearing shell (5)
ø 65 mm

© BMW AG, Service Training

N42 Engine Chapter 3 P.50

Course Contents/Background Material

KT-6505
Fig. 73: Crankshaft with thrust bearing

Flywheel

KT-6380

Fig. 74: Dual-mass flywheel

A dual-mass flywheel is fitted.

© BMW AG, Service Training

N42 Engine Chapter 3 P.51

Course Contents/Background Material

Connecting rod and piston

KT-6692

Fig. 75: Connecting rod and piston assembly

Index Explanation Index Explanation

1 Plain rectangular compression 3 3-piece oil scraper ring
ring
2 Taper face ring

The connecting rod is made of steel and is cracked. The shape

of the small connecting rod eye is trapezoidal. The pin diameter
is 20 mm, the bearing diameter 50 mm.
The piston is a cast full slipper skirt piston with valve pockets in
the crown. The pistons of the N42B18/B20 are identical.
A new feature is the cooling by means of oil spray nozzles on the
exhaust side. Previously the cooling was on the intake side.

© BMW AG, Service Training

N42 Engine Chapter 3 P.52

Course Contents/Background Material

Power transmission area

KT-6845

Fig. 76: Trapezoidal piston principle

Index Explanation Index Explanation

1 Piston 3 Connecting rod
2 Gudgeon pin

The drawing above left shows a U-slot piston (trapezoidal); the

drawing on the right shows a standard piston.
The combustion pressure acts via the piston crown on the
gudgeon pin and in turn on the connecting rod. Thanks to the
trapezoidal shape the area (green power transmission area) via
which the force is transmitted is larger than in a standard piston.

© BMW AG, Service Training

N42 Engine Chapter 3 P.53

Course Contents/Background Material

Lubrication system

Technical data

Oil capacity in litres Explanation

5.00 Total filling capacity for first fill at factory
4.25 Filling capacity for service with oil filter change
1.25 Filling capacity between MIN/MAX mark on dipstick

Oil pressure Explanation

1.5 - 2.0 bar Minimum oil pressure at 20 ºC
4.0 - 6.0 bar Maximum oil pressure at 20 ºC

Oil delivery capacity Explanation

9 - 12 l/min At idle speed (700 rpm) at 20 ºC
50 - 55 l/min At maximum engine speed (6500 rpm) and 20 ºC

© BMW AG, Service Training

N42 Engine Chapter 3 P.54

Course Contents/Background Material

Oil circuit

4 5
2 6
3
1

7
9
8
13
11 14
10

12

16
15

17

18 19
KT-6725

Fig. 77: Oil circuit

Index Explanation Index Explanation

1 VANOS exhaust side 11 Hydraulic valve lash adjusters
2 Exhaust camshaft 12 Non-return valves
3 VANOS "Tank" 13 Unfiltered oil gallery from oil pump
4 Oil spray rails 14 Filtered oil gallery from oil filter
5 Vacuum pump supply 15 Oil spray nozzles
6 Intake camshaft 16 Crankshaft bearings
7 Solenoid valve, exhaust 17 Chain tensioner for oil pump drive
VANOS
8 Solenoid valve, intake VANOS 18 Unfiltered oil gallery from oil pump
9 Chain tensioner 19 Counterbalance shaft connection
10 VANOS intake side

© BMW AG, Service Training

N42 Engine Chapter 3 P.55

Course Contents/Background Material

KT-6423

Fig. 78: Non-return valves (12) in oil gallery

Oil pump

1 2

KT-6500
Fig. 79: Gear pump stage 1 (1) and stage 2 (2)

Two-stage oil pump with 2 pairs of gearwheels one behind the

other.
Stage 2 is deactivated hydraulically at a pressure of 2 bar. It is
active only in the lower engine speed range (up to approx.
2000 rpm) in order to make available sufficient oil pressure for
the VANOS at high oil temperatures.

KT-6502

Fig. 80: Oil pump (arrow)

© BMW AG, Service Training

N42 Engine Chapter 3 P.56

Course Contents/Background Material

Oil pressure control

KT-6555 KT-6556

Fig. 81: Oil pressure control valve in initial position, depressurized (left) and under
2 bar oil pressure (right)

KT-6557 KT-6729

Fig. 82: Oil pressure control valve with stage 2 deactivated (left) and high pressure
control (right)

Index Explanation Index Explanation

1 Oil pump stage 1 5 Screw plug
2 Oil pump stage 2 6 Oil pump housing
3 Piston of pressure control valve 7 Engine oil pan
4 Spring of pressure control valve

© BMW AG, Service Training

N42 Engine Chapter 3 P.57

Course Contents/Background Material

Oil filter

A full-flow oil filter with oil-to-water heat exchanger is fitted.

1 2

KT-6408

Fig. 83: Oil filter (1) with oil-to-water heat exchanger (2)

Oil cooling

The oil-to-water heat exchanger is connected both to the oil

circuit as well as to the water circuit of the engine. This
arrangement ensures that the coolant quickly heats up the
engine oil when the engine is cold and the coolant cools the
engine oil when the engine is hot. Shortening the warm-up
phase contributes to reducing the overall fuel consumption. The
engine oil is cooled in order to extend its service life.

KT-6407
Fig. 84: Oil filter with oil-to-water heat exchanger

© BMW AG, Service Training

N42 Engine Chapter 3 P.58

Course Contents/Background Material

Oil spray nozzles

KT-6506
Fig. 85: Oil spray nozzles for piston crown cooling

The oil spray nozzles are arranged on the exhaust side.

Consequently, the heat on the exhaust side can be dissipated
more effectively.

Oil lubrication camshaft

KT-6409
Fig. 86: Oil spray nozzles for camshaft and eccentric shaft lubrication

© BMW AG, Service Training

N42 Engine Chapter 3 P.59

Course Contents/Background Material

Service notes

Lubrication system

The oil filler cover is a two-piece component. Both parts are

connected by means of a hinge. The retaining ring (2) is clipped
onto the neck (3) of the valve cover.

1
3

KT-6406
Fig. 87: Captive oil filler cover

Index Explanation Index Explanation

1 Oil filler cover 3 Neck
2 Retaining ring

An arrow (in the circle in the figure above) is marked on the

retaining ring and on the filler neck of the valve cover to facilitate
assembly and disassembly.
The retaining ring can be easily removed from or fitted on the
filler neck when both arrows are aligned.

© BMW AG, Service Training

N42 Engine Chapter 4 P.1

Course Contents/Background Material

N42 engine management

New features ME 9.2
Introduction
In view of more stringent emission requirements as well as
endeavours to reduce fuel consumption and to increase driving
dynamics the newly developed Bosch engine management
system ME 9.2 is to be introduced worldwide.
A flash EPROM is used as the storage medium for the program,
data, fault code memory as well as the adaptation values.
The control unit plug connector is of modular design and
features 5 connector modules in an SKE housing with a total of
134 pins.
The ME 9.2 control unit is the same for all N42 engine variants in
the different models. The engine management data are
programmed corresponding to the specific variant.
The ME 9.2 control unit is combined with the BMW
development, i.e. the Valvetronic control unit.
The ME 9.2 control unit is responsible for the engine
management of the N42 engine.
The task of the Valvetronic control unit is to control the valve lift
of the intake valves.

© BMW AG, Service Training

N42 Engine Chapter 4 P.2

Course Contents/Background Material

Overview ME 9.2

KT-6389

Fig. 1: Block diagram ME 9.2

© BMW AG, Service Training

N42 Engine Chapter 4 P.3

Course Contents/Background Material

Index Description
A1 Ignition lock
ABS/ASC Anti-lock brake system/traction control
DIAG Diagnostic plug
DISA Variable-geometry intake system (N42 B20 only)
DME/ME 9.2 Engine control unit
EDK Electronic throttle valve
EV 1-4 Fuel injectors 1 to 4
EWS3 Electronic vehicle immobilisation 3
FPM Accelerator pedal module
G Alternator
HFM Hot-film air mass meter
K1 DME relay
K2 Electric fuel pump relay
K3 Compressor relay
K4 Secondary air pump relay
K5 Power supply relay ignition coils 1-4
KS 1 Knock sensor 1
KS 2 Knock sensor 2
KT Characteristic map thermostat
KWG Crankshaft sensor
L Electronic fan
LSH 1 Oxygen sensor after catalytic converter 1
LSH 2 Oxygen sensor after catalytic converter 2
LSV 1 Oxygen sensor before catalytic converter 1
LSV 2 Oxygen sensor before catalytic converter 2
MFL Multifunction steering wheel
NTC 1 Radiator water outlet temperature sensor
NTC 2 Coolant temperature sensor
NWGA Exhaust camshaft sensor
NWGE Intake camshaft sensor
P1 Pressure sensor, intake system
P2 Ambient pressure sensor
S1 Clutch switch
S2 Brake switch
SLP Secondary air pump
TEV Fuel tank vent valve
TÖNS Thermal oil level sensor
VA VANOS exhaust camshaft
VE VANOS intake camshaft
V SG Valvetronic control unit
ZS 1-4 Rod-type ignition coils 1 to 4

© BMW AG, Service Training

N42 Engine Chapter 4 P.4

Course Contents/Background Material

Pin Type Description/type of signal Connection/measurement note

X6001 9-pin black Plug connector, DME module 1

1-01 I Voltage supply, terminal 15 End of line programming

1-02 Not used

1-03 D TxD End of line programming

1-04 G Ground Earth/ground point

1-05 G Ground Earth/ground point

1-06 G Ground Earth/ground point

1-07 I Voltage supply, terminal 30 Fuse F4

1-08 I Terminal 87 Fuse F1

1-09 O Activation, DME relay DME relay

X6002 24-pin black Plug connector, DME module 2

2-01 O Oxygen sensor heating Oxygen sensor 1 before catalytic

converter

2-02 O Oxygen sensor heating Oxygen sensor 2 before catalytic

converter

2-03 D CAN-bus vehicle low CAN-bus vehicle low

2-04 D CAN-bus vehicle high CAN-bus vehicle high

2-05 Not used

2-06 O Ground supply, oxygen sensor heater Oxygen sensor 1 after catalytic
converter

2-07 G Virtual ground, oxygen sensor Oxygen sensor 1 before catalytic

converter

2-08 G Ground, oxygen sensor signal Oxygen sensor 2 after catalytic

converter

2-09 G Virtual ground, oxygen sensor Oxygen sensor 2 before catalytic

converter

2-10 G Ground signal, oxygen sensor Oxygen sensor 1 after catalytic

converter

2-11 Not used

2-12 O Ground supply, oxygen sensor heater Oxygen sensor 2 after catalytic
converter

2-13 O Pump current, constant oxygen sensor Oxygen sensor 1 before catalytic
converter

2-14 I Oxygen sensor signal Oxygen sensor 2 after catalytic

converter

2-15 O Pump current, constant oxygen sensor Oxygen sensor 2 before catalytic
converter

2-16 I Oxygen sensor signal Oxygen sensor 1 after catalytic

converter

2-17 Not used

2-18 Not used

2-19 I Pump current, constant oxygen sensor (ground signal) Oxygen sensor 1 before catalytic
converter

2-20 I Oxygen sensor reference cell Oxygen sensor 1 before catalytic

converter

2-21 I Pump current, constant oxygen sensor (ground signal) Oxygen sensor 2 before catalytic
converter

2-22 I Oxygen sensor reference cell Oxygen sensor 2 before catalytic

converter

© BMW AG, Service Training

N42 Engine Chapter 4 P.5

Course Contents/Background Material

Pin Type Description/type of signal Connection/measurement note

2-23 O Activation, DME relay DME relay

2-24 Not used

X6003 52-pin black Plug connector, DME module 3

3-01 I Signal, hot-film air mass meter Hot-film air mass meter

3-02 I Pressure sensor signal

3-04 O Voltage supply HFM5 HFMREF

3-05 I TOENS signal Thermal oil level sensor

3-06 O Negative activation, fuel injector Fuel injector

3-07 O Negative activation, fuel injector Fuel injector

3-08 Not used

3-09 O Signal, VANOS valve Exhaust camshaft

3-10 O Signal, VANOS valve Intake camshaft

3-11 Not used

3-12 O Negative activation, characteristic map thermostat Characteristic map thermostat

3-13 O Negative activation, fuel injector Fuel injector

3-14 G Ground, hot film air mass sensor Throttle potentiometer 2

3-15 Not used

3-16 Not used

3-17 Not used

3-18 O Emergency operation signal Valvetronic Activation

3-19 D Alternator Alternator output

3-20 Not used

3-21 O TEV Fuel tank ventilation

3-22 Not used

3-23 Not used

3-24 Not used

3-25 O Negative activation, fuel injector Fuel injector

3-26 Not used

3-27 I Crankshaft sensor signal Crankshaft sensor

3-28 I NTC signal Coolant temperature

3-29 I Camshaft sensor signal Intake camshaft

3-30 I Camshaft sensor signal Exhaust camshaft

3-31 I DKG1 signal Throttle position

3-32 I DKG2 signal Throttle position

3-33 I KS1-2 Knock sensor signal

3-34 I KS3-4 Knock sensor signal

3-35 G NTC ground Coolant temperature

3-36 O NWG ground Exhaust camshaft

3-37 G KWG Crankshaft sensor

3-38 D LoCAN engine high Valvetronic control unit

3-39 Not used

3-40 O DISA activation 1

© BMW AG, Service Training

N42 Engine Chapter 4 P.6

Course Contents/Background Material

Pin Type Description/type of signal Connection/measurement note

3-41 O DISA activation 2

3-42 O Activation, throttle motor Throttle valve actuation

3-43 O Activation, throttle motor Throttle valve actuation

3-44 Not used

3-45 I DISA

3-46 I KS1-2 Knock sensor signal

3-47 I KS 3-4 Knock sensor signal

3-48 G NWG ground Intake camshaft

3-49 Not used

3-50 O DKG activation Throttle potentiometer

3-51 D LoCAN engine low Valvetronic control unit

3-52 G DKG Throttle sensor

X6004 40-pin black Plug connector, DME module 4

4-01 Not used

4-02 Not used

4-03 O SLP1 Secondary air pump relay

4-04 O Signal, auxiliary fan motor Auxiliary fan motor

4-05 G Body ground Terminal 31

4-06 I Start signal, terminal 50 Ignition/starter switch

4-07 G Ground, pedal position sensor Accelerator pedal sensor

4-08 I Signal, pedal position sensor Accelerator pedal sensor

4-09 O Supply, pedal position sensor Accelerator pedal sensor

4-10 O Activation, fuel pump relay (EKP) EKP relay for ECE

4-11 Not used

4-12 G Ground, pedal position sensor Accelerator pedal sensor

4-13 I Signal, pedal position sensor Accelerator pedal sensor

4-14 O Supply, pedal position sensor Accelerator pedal sensor

4-15 Not used

4-16 Not used

4-17 O Output, engine speed signal (TD) Diagnostic plug

4-18 Not used

4-19 Not used

4-20 Not used

4-21 Not used

4-22 I ASC ASC control unit

4-24 I Signal, brake light switch (ASC) Brake light switch

4-26 I Voltage supply, terminal 15 Fuse

4-27 O Voltage supply, multifunction steering wheel MFL

4-28 O Signal, brake light switch Brake light switch

4-29 I Signal, A/C compressor relay (KOREL) Heater and air conditioner

4-30 Not used

4-32 O TXD diagnosis signal To instrument cluster

© BMW AG, Service Training

N42 Engine Chapter 4 P.7

Course Contents/Background Material

Pin Type Description/type of signal Connection/measurement note

4-33 I/O Communication line (EWS) Electronic vehicle immobilisation

4-34 Not used

4-35 W CAN-bus CAN connection

4-36 I/O CAN-bus vehicle high CAN connection vehicle

4-37 I/O CAN-bus vehicle low CAN connection vehicle

4-38 G Ground Temperature sensor, radiator outlet

4-39 I Radiator outlet temperature Temperature sensor, radiator outlet

X6005 9-pin black Plug connector, DME module 5

5-01 Not used

5-02 O Signal, terminal 1 Ignition coil, cylinder 4

5-03 O Signal, terminal 1 Ignition coil, cylinder 1

5-04 Not used

5-05 G Ground Earth/ground point

5-06 O Signal, terminal 1 Ignition coil, cylinder 2

5-07 Not used

5-09 O Signal, terminal 1 Ignition coil, cylinder 3

© BMW AG, Service Training

N42 Engine Chapter 4 P.8

Course Contents/Background Material

Components
All components of the engine management ME 9.2 are listed in
the following. The variable-geometry intake system (DISA) is
installed only in the N42B20 engine.

Sensors

- Accelerator pedal module (FPM)

- Hot-film air mass meter (HFM)
- Knock sensor 1 (KS1)
- Knock sensor 2 (KS2)
- Crankshaft sensor
- Oxygen sensor after catalytic converter 1 (LSH1)
- Oxygen sensor after catalytic converter 2 (LSH2)
- Oxygen sensor before catalytic converter 1 (LSV1)
- Oxygen sensor before catalytic converter 2 (LSV2)
- Radiator water outlet temperature sensor (NTC1)
- Water temperature sensor (NTC2)
- Exhaust camshaft sensor (NWGA)
- Intake camshaft sensor (NWGE)
- Pressure sensor, intake system (P1)
- Thermal oil level sensor (TÖNS)
- Ambient pressure sensor in engine control unit (P2)

Actuators

- Variable-geometry intake system (DISA) N42B20 only

- Electronic throttle valve (EDK)
- Fuel injectors 1-4 (EV 1-4)
- Electronic fan (L)
- Secondary air pump (SLP)
- Fuel tank vent valve (TEV)
- VANOS exhaust camshaft (VA)
- VANOS intake camshaft (VE)
- Valvetronic control unit (V SG)
- Rod-type ignition coils 1 to 4
- Characteristic map thermostat

© BMW AG, Service Training

N42 Engine Chapter 4 P.9

Course Contents/Background Material

Switches

- Ignition lock (A1)

- Multifunction steering wheel (MFL, cruise control)
- Clutch switch (S1)
- Brake switch (S2)

Relays

- DME relay (K1)

- EKP relay (K2)
- Compressor relay (K3)
- Secondary air pump relay (K4)
- Power supply relay ignition coils 1-4 (K5)

Interfaces

- Diagnosis connector (DIAG)

- CAN-bus vehicle high (CAN F)
- CAN-bus vehicle low (CAN F)
- Local CAN-bus engine high (CAN P)
- Local CAN-bus engine low (CAN P)

© BMW AG, Service Training

N42 Engine Chapter 4 P.10

Course Contents/Background Material

Functional description ME 9.2

VANOS

General

The functions of the N42 VANOS are identical to the VANOS

systems already known (e.g. M54). The design and installation
have been simplified.

1
3
4
2

KT-6421

Fig. 2: Camshaft sensors and VANOS solenoid valves

Index Explanation Index Explanation

1 Solenoid valve, exhaust 3 Camshaft sensor, exhaust
VANOS
2 Solenoid valve, intake VANOS 4 Camshaft sensor, intake

The solenoid valve is controlled by the DME control unit and

switches the engine oil pressure for VANOS adjustment.

KT-6420

Fig. 3: VANOS solenoid valve

© BMW AG, Service Training

N42 Engine Chapter 4 P.11

Course Contents/Background Material

Possible faults/effects

Any faults that occur in the VANOS system are detected and
stored by the DME. For the driver, a malfunction is reflected in
power loss and increased fuel consumption. The malfunction
indicator lamp (MIL) is activated as a VANOS fault is relevant to
exhaust emissions.

Special features

The control piston in the VANOS solenoid valves moves with a

high degree of precision. Compared to positioning of the control
piston directly in the cylinder head, this arrangement offers
specific advantages with regard to assembly and reliability of
the system.

Secondary air system

General

Thermal post-combustion of the uncombusted hydrocarbon

contained in the exhaust gas is achieved by injecting additional
air (secondary air) into the exhaust gas during the cold start
phase. At the same time, the catalytic converter is heated to its
operating temperature at a faster rate so as to reduce the level
of pollutants in the exhaust gas.
The design and function of the secondary air system are
comparable to those of the systems already known. Air injection
takes place directly in the exhaust port of the cylinder head.
Secondary air ports are cast in the cylinder head for this
purpose.
Vehicles with no catalytic converter are not equipped with
secondary air injection.

Possible faults/effects

A malfunction in the secondary air system is not discernible for

the driver. However, a fault code relating to the exhaust gases is
stored in the fault code memory and the MIL is activated.

© BMW AG, Service Training

N42 Engine Chapter 4 P.12

Course Contents/Background Material

Emission control

General

A total of four oxygen sensors are fitted for the N42 engine. A
planar wideband oxygen sensor (constant characteristic curve)
for controlling the fuel-air mixture is fitted before each of the two
primary catalytic converters.
A monitor oxygen sensor (jump characteristic) is located after
the main catalytic converter for the purpose of monitoring the
overall performance of the catalytic converter.
With the aid of this monitoring facility, the malfunction indicator
lamp is activated and a fault code stored in the event of
impermissibly high exhaust gas concentrations.
A monitor sensor (jump characteristic) is also fitted after a
primary catalytic converter for the purpose of synchronizing the
exhaust gases of both primary catalytic converters. With this
arrangement it is possible to detect an emission-relevant fault in
an oxygen sensor of a primary catalytic converter which
otherwise is not noticeable in the overall exhaust gas system.
Example:
A value of λ>1 is determined at one primary catalytic converter
and a value of λ<1 at the other primary catalytic converter.
Although impermissible deviations occur at the two catalytic
converters, the oxygen sensor after the main catalytic converter
determines λ=1. This fault can now be detected by the additional
oxygen sensor after a primary catalytic converter.

Planar wideband oxygen sensor

The N42 is equipped with a new, planar wideband oxygen

sensor (primary catalytic converter oxygen sensor). In contrast
to conventional oxygen sensors, the sensor element of the
planar wideband oxygen sensor is made up of layers of
zirconium dioxide (ZrO2) ceramic films. This modular structure
enables the integration of several functions.
The heating element mounted in a laminate ensures the
minimum operating temperature of 750 ºC is reached rapidly.

© BMW AG, Service Training

N42 Engine Chapter 4 P.13

Course Contents/Background Material

KT-6687

Fig. 4: Sensor element design

Index Explanation Index Explanation

1 Exhaust gas 7 Zirconium ceramic layer
2 Pump cell (gauge head) 8 Measuring gap
3 Platinum electrode, 9 Reference cell
reference cell
4 Heating electrode 10 Platinum electrode, reference cell
5 Heating element 11 Platinum electrode, pump cell (gauge
head)
6 Reference air gap 12 Platinum electrode, pump cell

Due to the combination of a reference cell (9) for λ=1 and a

pump cell or gauge head (2) transporting oxygen ions in the
sensor element, the wideband sensor can measure not only at
λ=1, but also in the rich and lean range (λ=0.7 to λ=air).

The pump cell or gauge head (2) and reference cell (9) are made
of zirconium dioxide and each coated with two porous platinum
electrodes. They are arranged such that there is a measuring
gap (8) of approx. 10 to 50 µm between them. This measuring
gap is connected by an inlet opening to the ambient exhaust gas
atmosphere. The voltage applied to the pump cell is controlled
by an electronic circuit in the DME such that the composition of
the gas in the measuring gap is constantly at λ=1.

© BMW AG, Service Training

N42 Engine Chapter 4 P.14

Course Contents/Background Material

If the exhaust gas is lean, the pump cell or gauge head pumps
oxygen away from the measuring gap to the outside while the
direction of flow is reversed in the case of rich exhaust gas and
oxygen is pumped from the ambient exhaust gas into the
measuring gap. The pump flow is proportional to the oxygen
concentration or the oxygen requirement.
The required current of the pump cell or gauge head is
evaluated by the DME as a signal relating to the exhaust gas
composition.

Note

To operate effectively, the oxygen sensor requires ambient air as

the reference gas in the inside of the sensor. The ambient air
reaches the inside of the sensor via the plug connection and
through the cable. The plug connection must therefore be
protected from soiling (wax, preservatives etc.).
In the event of the oxygen sensor malfunctioning, the
connector should always be checked first with regard to
soiling and cleaned if necessary. The plug connection
must be disconnected and then reconnected (in order to
remove any oxidation from the connector).

Signals

The oxygen sensor heating is powered by the vehicle electrical

system (13 V) and clocked cyclically by the control unit. The
cyclic clock is based on a characteristic map.
At a lambda value of 1, the oxygen sensor signal has a voltage
of 1.5 V. At a lambda value of infinity (pure air), the voltage
is 4.3 V.
The oxygen sensor has a virtual ground of 2.5 V.
The pump current of the constant oxygen sensor is approx.
3 mA.
The pump cell of the constant oxygen sensor supplies a ground
signal of approx. 3 mA.
The reference cell of the constant oxygen sensor supplies a
voltage of approx. 450 mV.

© BMW AG, Service Training

N42 Engine Chapter 4 P.15

Course Contents/Background Material

Ambient pressure sensor

General

The pressure sensor is located in the DME control unit. This

sensor enables continuous measurement of the air pressure.
The signal is used in the DME to calculate the altitude correction
for forming the mixture and as a reference value for the intake
pipe pressure.
The voltage supply is 5 V. The resistance of the sensor is
dependent on pressure. The output voltage is processed by the
DME in the form of a signal voltage.

Intake pipe pressure sensor

General

The pressure sensor is located in the intake pipe behind the

throttle valve. The voltage supply is 5 V. The resistance of the
sensor is dependent on pressure. The output voltage is
processed by the DME in the form of a signal voltage.
The set intake pipe pressure calculated by the DME is compared
with the measured intake pipe pressure.

KT-6391
Fig. 5: Pressure sensor in the intake system

© BMW AG, Service Training

N42 Engine Chapter 4 P.16

Course Contents/Background Material

Possible faults/effects

A corresponding fault code is stored in the event of deviations

between the calculated (set) and measured intake pipe pressure.
The intake system should be checked for leaks if the fault code
"plausibility differential pressure" is stored.

Special features

An intake pipe vacuum of 50 mbar is required for the tank

ventilation function. This vacuum is set by the throttle valve and
monitoring with the intake pipe pressure sensor.
The ambient pressure sensor serves as a reference sensor for
the intake pipe pressure sensor. Both sensor signals are
constantly compared with each other thus registering the intake
pipe pressure.

© BMW AG, Service Training

N42 Engine Chapter 4 P.17

Course Contents/Background Material

Valvetronic
General

Overview Valvetronic

KT-6673

Fig. 6: Block diagram Valvetronic

A separate control unit is used for controlling the Valvetronic

(development of the BMW Group).

Index Description
DME Digital motor electronics
K1 DME main relay
K2 Load-relief relay
M Electric motor for eccentric shaft adjustment
V SG Valvetronic control unit
VS Eccentric shaft sensor

Pin Type Description/type of signal Connection/measurement note

X60212 10-pin Connector Valvetronic control

unit module 1

1-01 I Voltage supply for power electronics

1-02 G Ground, Valvetronic control unit

1-03 I Load-relief relay activation

1-04 Not used

1-05 Not used

1-06 O Motor activation

1-07 O Motor activation

1-08 Not used

1-09 Not used

© BMW AG, Service Training

N42 Engine Chapter 4 P.18

Course Contents/Background Material

Pin Type Description/type of signal Connection/measurement note

1-10 Not used

X60211 24-pin Connector Valvetronic control

unit module 2

2-01 I Voltage supply

2-02 O Voltage supply, sensor

2-03 O Signal, control sensor (chip select)

2-04 I Signal, control sensor (data)

2-05 I Clock signal for data transfer, control sensor and

reference sensor (clock)

2-06 Not used

2-07 D LoCAN engine high

2-08 Not used

2-09 Not used

2-10 Not used

2-11 Not used

2-12 Not used

2-13 I Input, emergency operation signal

2-14 Not used

2-15 G Sensor shield

2-16 G Sensor ground

2-17 O Signal, reference sensor (chip select)

2-18 I Signal, reference sensor (data)

2-19 D LoCAN engine low

2-20 Not used

2-21 Not used

2-22 Not used

2-23 Not used

2-24 Not used

© BMW AG, Service Training

N42 Engine Chapter 4 P.19

Course Contents/Background Material

Eccentric shaft sensor

The task of the eccentric shaft sensor is to determine the exact
position of the eccentric shaft.

KT-6431
Fig. 7: Eccentric shaft sensor

1 2

KT-6438

Fig. 8: Rod-type ignition coil connector (1) and eccentric shaft sensor connector (2)

© BMW AG, Service Training

N42 Engine Chapter 4 P.20

Course Contents/Background Material

Electric motor for eccentric shaft adjustment

The electric motor for adjusting the eccentric shafts is located in
the centre of the cylinder head. To facilitate adjustment, the
spindle of the motor engages in the gearing of the eccentric
shaft. The electric motor is driven by the Valvetronic control unit.

KT-6430
Fig. 9: Electric motor for eccentric shaft adjustment

© BMW AG, Service Training

N42 Engine Chapter 4 P.21

Course Contents/Background Material

Functional description Valvetronic

Eccentric shaft sensor

Sensor type

The eccentric shaft sensor operates in accordance with the

magnetoresistive principle, i.e. the effect of a magnetic field
changes the resistance of a ferromagnetic conductor.

Description

The sensor is of redundant design. Both sensor elements are

accommodated in one housing. One sensor undertakes the
management function while being monitored by the reference
sensor. The sensors are arranged in opposition. When the
eccentric shaft is moved from zero lift in the direction of
maximum lift, the control sensor supplies ascending angle
values and the reference sensor descending angle values.

© BMW AG, Service Training

N42 Engine Chapter 4 P.22

Course Contents/Background Material

Function

A strong permanent magnet is mounted on a rotary shaft

(eccentric shaft) for the purpose of measuring the absolute
angular position of this shaft.

KT-6872

Fig. 10: Magnetoresistive principle

Index Explanation Index Explanation

1 Magnetoresistive element 3 Direction of rotation of magnetic
with resistance R (α) field

2 Lines of magnetic field 4 Current flow I

The resistance R (α) of the magnetoresistive element (1) is

dependent on the direction of the lines of magnetic field (2).
The magnetoresistive element consists of a ferromagnetic layer.
The sheet resistance is solely dependent on the angle α under
the influence of a sufficiently strong magnetic field. The
magnetic field is generated by permanent magnets.
The data are transmitted over the "clock, data and chip select"
lines via a serial interface (DS) from the eccentric shaft sensor to
the Valvetronic control unit.
The angle values of the control sensor and of the reference
sensor are in opposition. The Valvetronic control unit constantly
compares the values with each other.
A stop learning routine is executed before starting the engine for
the purpose of determining the mechanical stops of the
eccentric shaft. This learning routine is always carried out when
a difference is determined between the off position and the start
position of the eccentric shaft while starting the engine.

© BMW AG, Service Training

N42 Engine Chapter 4 P.23

Course Contents/Background Material

For this purpose, the eccentric shaft is moved once from zero lift
to full lift. The end position as well as the initial position are
stored.
The stop learning routine can be called up by the MoDiC or DIS.
The measuring range of the sensor is 180º.

Signals

The Valvetronic control unit supplies the sensor with a voltage

of 5 V.
Data transfer from the eccentric shaft sensor to the Valvetronic
control unit takes place over a mean clock frequency of
250 kHz.

Possible faults/effects

In the event of the eccentric shaft sensor failing, this situation is

recognized by the Valvetronic control unit and signalled in the
form of an error message to the DME. The power supply to the
motor is cut immediately. The fault is then acknowledged by the
DME and the electric motor is driven to the full stop position
(maximum valve lift) for the purpose of adjusting the eccentric
shaft. The throttle valve then controls metering of the intake air.
If only the signal of the control sensor (sensor 1) fails, the system
switches over to the reference sensor (sensor 2). The plausibility
of both sensors is then no longer checked.
A corresponding fault code is stored in the event of the
reference sensor failing. The system continues to operate
normally.

Note

Particular care must be taken when replacing the eccentric shaft

sensor to ensure that the magnetic wheel is mounted on the
eccentric shaft with a non-magnetic special steel screw
tightened to the specified torque.

© BMW AG, Service Training

N42 Engine Chapter 4 P.24

Course Contents/Background Material

Electric motor for eccentric shaft adjustment

Type of motor

The electric motor for adjusting the eccentric shaft is a clock-

controlled 12 V DC motor.

Description

The electric motor is driven by the Valvetronic control unit. The

eccentric shaft is correspondingly adjusted by reversing the
direction of rotation and the duration of clocked activation. The
electric motor can draw a current of up to 40 A at maximum
adjustment.

Possible faults/effects

In the event of the motor or its activation function failing, this

situation is detected by the Valvetronic control unit and signalled
to the DME. Power supply to the motor is cut and a fault code is
stored in the DME. As an emergency operation function, the
intake air is then metered by the throttle valve.

© BMW AG, Service Training

N42 Engine Chapter 4 P.25

Course Contents/Background Material

Valvetronic control unit

General

The power to the Valvetronic control unit is supplied via the main
relay of the DME. The control commands from the DME are
transferred via a LoCAN motor high to the Valvetronic control
unit.
The Valvetronic control unit and the load-relief relay are installed
under the battery. The Valvetronic also undertakes the ASC and/
or DSC throttle valve functions.

Possible faults/effects

Faults that may occur are initially filtered in the Valvetronic

control unit. Detected faults are then transferred via the LoCAN
motor to the DME and the power supply to the electric motor for
adjusting the eccentric shaft is initially disconnected.
The DME acknowledges the fault to the Valvetronic control unit.
The response in the Valvetronic control unit depends on the
cause of the fault.
If the cause of the fault is not in the electric motor for adjusting
the eccentric shaft and its activation system, the Valvetronic
control unit will initiate an emergency operation program. The
eccentric shaft is then set to full lift and the intake air controlled
by the throttle valve.
The malfunction indicator lamp is not activated as this is not an
emission-relevant fault.

© BMW AG, Service Training

N42 Engine Chapter 4 P.26

Course Contents/Background Material

Idle speed control

General

The idle speed is controlled by the Valvetronic thus rendering

the idle actuator unnecessary.
The idle speed control has been correspondingly adapted to
facilitate use of the Valvetronic. During the starting procedure,
the air volume is controlled by the throttle valve.
With the engine at operating temperature, the system changes
to non-throttled operation after approx. 60 seconds (throttle
valve fully opened).
However, the engine is started with the throttle valve fully
opened under cold weather conditions as this has a positive
effect on the starting behaviour.

Note

In the event of a malfunction in the idle speed control, the

engine should be initially checked for leaks as leakage air has an
immediate effect on the idle speed. This is also noticeable, for
example, when the oil dipstick is missing.

© BMW AG, Service Training

N42 Engine Chapter 5 P.1

Course Contents/Background Material

N42 fuel system

Mixture control

General

The mixture control system was essentially adapted to that of

the M54.
The pressure regulator is integrated in the fuel filter and both
can be replaced only as a complete unit. There is now only one
fuel return line between the fuel filter and fuel tank. The fuel
pressure regulator is subject to the ambient air pressure. A hose
is fitted from the vacuum connection of the pressure regulator to
the intake system to ensure no fuel can reach the outside in the
event of leaks in the pressure regulator. The hose is connected
behind the air mass meter and before the throttle valve.
The fuel system pressure is 3.5 bar.

Fuel tank ventilation

General

Compared to the predecessor, the fuel tank ventilation has been

greatly relieved (larger cross sections). This measure ensures
that the tank ventilation system functions satisfactorily even at
the slight intake pipe vacuum (50 mbar).

© BMW AG, Service Training

N42 Engine Chapter 5 P.2

Course Contents/Background Material

Fuel tank vent valve

The figure below shows the connection of the carbon canister

valve (AKF valve) to the intake system.

KT-6387
Fig. 1: Fuel tank vent valve (AKF valve)

© BMW AG, Service Training

N42 Engine Chapter 6 P.1

Course Contents/Background Material

N42 clutch
SAC - Self adjusting clutch
Introduction
A slightly modified version of the self-adjusting clutch
introduced in 1996 is also fitted in the N42.

KT-6381
Fig. 1: N42 self-adjusting clutch installed

Index Explanation Index Explanation

1 Ramps 3 Compression spring
2 Thrust piece of adjustment
wedges

A metal ring (previously plastic ring) with adjustment wedges

arranged on the circumference is located under the ramps.

© BMW AG, Service Training

N42 Engine Chapter 6 P.2

Course Contents/Background Material

KT-6380
Fig. 2: N42 self-adjusting clutch removed with dual-mass flywheel

KT-6382
Fig. 3: Inscription on clutch disc

Notes on maintenance and repair

A wear check is no longer necessary on all BMW models
equipped with the self-adjusting clutch.

© BMW AG, Service Training

N42 Engine Chapter 6 P.3

Course Contents/Background Material

KT-6380

Fig. 4: N42 self-adjusting clutch with special tool

The self-adjusting clutch is installed and removed in the same

way as the previous clutches.
The exact procedure is described in the repair instructions.

© BMW AG, Service Training