Engine

Fuel system

HITACHI INTEGRATED INJECTION-IGNITION SYSTEM

Introduction

The Hitachi system fitted to the Barchetta model with 1747 i.e. 16v engine belongs to the category of
digital electronic ignition systems with static advance and timing, integrated with a phased, multipoint,
intermittent electronic fuel injection system.
This system therefore adopts a single ECU, single wiring system and a set of sensors common to both
systems.
The integrated system may be divided schematically into the following subsystems:

ELECTRIC/ELECTRONIC CIRCUIT
AIR INTAKE CIRCUIT
FUEL FEED CIRCUIT
EMISSION CONTROL DEVICES

The system is able to monitor the following parameters by means of dedicated sensors:
1. instantaneous engine rpm;
2. position of each piston pair in relation to TOC of cylinder 1;
3. engine air intake;
4. accelerator throttle position and position variation rate;
5. coolant temperature;
6. actual mixture concentration (via lambda probe signal);
7. presence of knock;
8. vehicle speed;
9. battery voltage;
10. whether a/c compressor activated.

This data, generallyanalogue,is converted into digital signals by analogue/digital (A/D) convertersso
that it may be used by the ECU.
Any engine operating point may be identified, instant by instant, by two parameters:
- engine speed, measuredin revolutions per minute (rpm);
- engine load, consisting of quantity of air taken in by each cylinder.
This quantity is computed on the basisof air intake and representedby the parameterTP, measuredin
milliseconds (ms).
The managementsoftware residentin the ECUmemorycomprisesa set of strategies.Eachof thesecon-
trols a specific systemcontrol function.
Eachstr~tegyusesthe various inputs listed aboveto processa set of parameters,using data mapssaved
in specific areasof the ECU.The resultingdata output is usedto control systemactuators,in other words
the devices used to operatethe engine, namely:
1. injectors;
2. ignition coils;
3. solenoids of various types;
4. fuel pump;
5. control relays.

NOTE ThisHITACHI injection-ignition sytem doesnot requireadjustmentbecauseit is self-adjusting

and self-adaptive.

NOTE Thenumbersin boxesin drawingsand diagramsindicate correspondingpin numbersin the HI-

TACHI engine ECU.

Copyright Fiat Auto 1

Engine Fiat barchetta
Fuel system
1.0.
HITACHI INJECTION-IGNITION SYSTEM OPERATING DIAGRAM

1. Fuel tank 19. Injector

2. Electric fuel pump 20. Timing variator solenoid
3. Fuel level gauge 21. Ignition power module
4. Anti-reflux valve 22. Ignition coil
5. Fuel filter 23. Engine timing sensor
6. Battery 24. Radiator fan
7. Ignition switch 25. Rpm sensor
8. Dual relay 26. Knock sensor
9. Air conditioner compressor 27. Coolant temperature sensor
10. Inertia switch 28. Carbon filter flushing solenoid
11. Vehicle speed sensor 29. Carbon filter
12. F/L Tester connector (diagnostic socket) 30. Ventilation valve
13. Rev counter 31. lambda probe
14. System warning light 32. Catalytic converter
15. Air flow meter 33. HITACHI engine control unit
16. Engine idle adjustment solenoid 34. Filler cap with pressure relief valve
17. Throttle position sensor 35. Fuel vapour separator
18. Fuel manifold with integral pressure regu- 36. Float valve
lator 37. FIAT CODE control unit

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Fiat barchetta Engine
Fuel system

DIAGRAM SHOWING INFORMATION FLOW BETWEEN HITACHI INJECTION-IGNITION SyS-

TEM ECU AND SENSOR/ACTUATORS

1. HITACHI engine control unit 14. Air conditioner compressor

2. Radiator fan relay 15. F/L Tester connector (tester socket)
3. Radiator fan 16. Carbon filter flushing solenoid
4. Speedometer 17. Idle speed adjustmentsolenoid
5. Vehicle speed sensor 18. Rev counter
6. Air flow meter 19. Injectors
7. Rpm sensor 20. Timing variator solenoid relay
8. Coolant temperature sensor 21. Timing variator solenoid
9. Throttle position sensor 22. Dual relay
10. lambda probe 23. Electricfuel pump
11. Ignition switch 24. Ignition power module
12. Knock sensor 25. Ignition coils
13. Engine timing sensor 26. Spark plugs
27. FIAT CODEcontrol unit

Copyright Fiat Auto 3

 Engine Fiat barchetta
Fuel system

LOCATION OF HITACHI INJECTION-IGNITION SYSTEM COMPONENTS IN ENGINE BAY

1. Ignition coils 15. lambda probe

2. Coolant temperature sensor 16. Ignition power module
3. Air flow meter 17. Timing variator solenoid
4. HITACH I engine control unit 18. Throttle position sensor
5. Dual relay 19. Idle speed adjustmentsolenoid
6. Fuses 20. Carbonfilter flushing solenoid
7. Rpm sensor 21. Knock sensor
8. Vehicle speed sensor 22. Injection-ignition systemearth
9. Fuel pressure regulator 23. Enginecontrol unit earth
10. Engine timing sensor 24. Coolant temperaturesensor(for instrument
11. Butterfly valve case panel)
12. Fuel manifold 25. Connection with vehicle wiring
13. Injectors 26. Enginecoolant radiator fan relay
14. Air conditioner compressor 27. Carbon filter

4 Publication no. 506.586/04

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Fiat barchetta Engine
Fuel system

SYSTEM OPERATING STRATEGIES

SIGNAL FRAMEWORK

Upon starting,the ECUidentifies injection and ignition timing, becausetheseparametersareessentialto

ensuresubsequentsuccessfulimplementationof all strategies.
Timing is identified by interpretinga seriesof signalsfrom a phonic wheel located on the crankshaftand
an engine timing sensor located on the camshaft.

NOTE Theterm "signal framework" denotesthe set of signalsproduced by a sensoron the crankshaft
and a sensoron the camshaft.Becausetheseare located in specific reciprocalpositions, they
provide the ECU with a synchronisedsequenceof signals that the ECU is able to identify.
The signal framework is produced as follows:
- phonic wheel on crankshaft: this comprises two symmetrical sets of teeth, arranged at 1 0°, 65° and 97°
in advance of each TOC respectively;
- camshaft wheel: comprises two long slots and one short slot, with width and arrangement designed to
provide the signal indicated in the figure.

1 1 3 4 2

I I I I

2 00 1800 3600 5400

P3WO5AJO1

1. Cylinder TOC
2. Crankshaft angles
3. Crankshaft phonic wheel signal (rpm sensor)
4. Camshaft wheel signal (engine timing sensor)

NOTE Numbersallocated to signals indicate crankshaftanglesaheadof subsequentTDC.

Copyright Fiat Auto 5

Engine Fiat barchetta
Fuel system

INJECTION MANAGEMENT

Injection managementstrategiesare designed to ensurethe engine is provided with the appropriate

quantity of fuel at the required time on the basis of engine operating conditions.

NOTE Becausethe flow meteris able to measureintake airmassdirectly,an intake air temperaturesen-
sor is not required.

Injection managementinvolvescomputing injection time, calculating injection phaseand then control-

ling the injector to implement the new setting.
Base pulse constant depends on injector characteristics and corresponds to the quantity of fuel to be in-
jected into each cylinder. Fuel quantity is calculated in turn by multiplying the quantity of air taken in by
each cylinder (calculated on the basis of intake air quantity and engine rpm) by the mixture concentra-
tion required for the specific engine operating point.
Final injection time is calculated using a computing algorithm whereby base pulse constant is corrected
by a series of factors that take into account various engine operating conditions as recorded by different
system sensors.

~ ~

---~' ;--
. ~
@

£,~"=l
~ ~ ~~ P3WO6AJO1

A: base pulse constant

B: correction factors: low engine temperature C: retro-active concentration control
high engine temperature D: self-adaption
starting and post-starting. E: cut-off
full throttle opening F: intermediateinjection time
over-run G: extra-pulse
acceleration H: non-phasedinjection management

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Fuel system

Control of mixture concentration (retro-active control)

NOTE Mixture ratio is defined and indicated by the Greek letter (X(alpha), as follows.
quantity of air taken in by engine
quantity of fuel injected

Stoichiometric ratio is defined and indicated by the symbol (Xstas follows:

theoretical quantity of air required to burn all the fuel injected

quantity of fuel injected

Mixture concentration is defined and indicated by the Greekletter A (lambda), as the ratio:

auantity of air taken in by enQine

theoretical quantity of air required to burn all the fuel injected

Thus we easily find that (XI Clst=A.

Stoichiometric ratio depends on fuel type. For unleaded fuels in current use, this figure is 14.7 - 14.8,
which corresponds to lambda = 1.
The mixture is termed rich (or heavy) when the quantity if air is less than the stoichiometric level. In this
case, lambda equals < 1 :
the mixture is termed lean (or light) when the quantity of air exceeds the stoichiometric level. In this
case, lambda equals> 1 .

The strategy is designed to correct base pulse constants so that mixture concentration oscillates contin-
ually and at a high rate between 0.98 and 1.02.
This oscillation rate varies according to engine load and speed. It is in the order of tens of Hertz.

NOTE 1 Hz = 1 oscillation per second

Under conditions of:

- cut-off,
- throttle opening greater than 70°,
- engine temperatureless than 25°C,
the strategy is de-activated.

Self-adaptability
The control unit features a self-adaptive function able to memorise deviations between basic maps and
corrections imposed by the lambda probe that occur persistently during operation. Such deviations (due
to system and engine component ageing) are saved permanently so that system operation can be adapt-
ed to gradual changes in engine and components with regard to original specifications.
The strategy is de~activated while the carbon filter flushing solenoid is open.
If the ECU is replaced, carry out a road test to enable the engine to warm up and the ECU autoadaptive
strategy to come into play (particularly important when idling at a standstill).

Copyright Fiat Auto 7

Engine
Fuel system

Starting and post-starting

During start-up, engine phase cannot be identified and phased injection cannot therefore be imple-
mented.
An initial simultaneous injection is carried out during the first few engine revolutions (the considerable
fluctuations in rotation speed do not permit injection time to be calculated correctly), but subsequently
injection becomes phased.
The base pulse constant is increased by a certain factor throughout the period when the engine is
cranked by the starter motor.
Once start-up has taken place, the factor is gradually reduced to zero within a given time period, which
is in inverse proportion to engine temperature.

k: enrichment factor
t: time
(1: decrease according to
engine temperature
ON: engine cranked
OFF: engine running
P3WO8AJO1

Cold operation

Under these conditions, the mixture becomes naturally leaner due to reduced evaporation and heavy fu-
el condensation on the intake manifold internal walls. The greater viscosity of the lubrication oil brings
about an increase in engine passive resistance.
Base pulse constant is corrected by a factor dependent upon temperature and engine speed.

Full-load

This strategy is enabled when throttle operation exceeds70°:

Base pulse constant is multiplied by a factor (dependent on engine speed) equivalent to about 1.1

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Fiat barchetta Engine
Fuel system

Acceleration

During this stage, the ECU increases the amount of fuel supplied.
Base pulse constant is multiplied by a factor dependent upon engine temperature and throttle opening
speed (average value 1.2).
If a sudden change in injection time is calculated when the injector is already closed, the ECU re-opens
the injector (extra pulse) to adjust concentration as quickly as possible. Subsequent injections are in-
creased on the basis of factors described above.

A
B
C
1
3 ~
,

4 m~ ~~

ON
OFF
P3WO9AJO1

A: normal injection time

B: injector re-opening (extra-pulse)
C: injection time including enrichment
OFF: engine under steady-state conditions
ON: engine under transient conditions

Over-run

During this stage, a negative transient strategy is implemented to reduce the quantity of fuel supplied.
Base pulse constant is multiplied by a factor dependent on engine temperature and engine speed and
load during the instant immediately prior to the start of over-run.

Cut-off

Fuel cut-off strategy is implemented when the ECU identifies throttle idle position (throttle poten-
tiometer signal) with engine speed greater than 1600 rpm (engine warm).
Fuel flow is re-established when throttle position is identified as not closed or when speed drops below
1200 rpm (with engine warm).

Copyright Fiat Auto 9

Engine Fiat barchetta
Fuel system

Rotation speed limiter

cyls.
This strategy limits maximum potential en- 1 2 3 4
gine speed by activating the cut-off gradual- mode
ly, as shown in the table.
Maximum speed: 7150 rpm.
1 cylinder 0

2 cylinders 0 0

3 cylinders 0 0 0

4 cylinders 0 0 0 0

Electric fuel pump drive

The electric fuel pump is governed by the engine ECU through a relay.
The pump is turned off:
- if engine speed drops below 50 rpm;
- after a certain time (about 5 seconds) with ignition switch turned to MAR without start-up taking
place (timed enablement);
- if inertia switch is triggered.

Injector control

Although controlled in sequential, phased manner, injectors are initally governed in parallel during
start-up
Injector control timing varies according to engine speed.

FIAT CODE ANTI-THEFT FUNCTION

The system features an anti-theft function. This is implemented--through a special FIAT CODE control
unit able to dialogue with the engine control unit, and an electronic key with a specific sender unit de-
signed for sending an identification code.
Once the key has been turned to STOP, the FIAT CODE system de-activates the engine control unit
completely.
When the key is turned to MAR, the following operations take place in sequence:
1. the engine control unit (whose memory contains a secret code) sends the FIAT CODE a request de-
manding that a secret code be sent to de-activate the function lock:
2. the FIAT CODE control unit responds by sending the secret code only after receiving a recognition
code sent by the ignition key;
3. recognition of the secret code allows the engine control unit lock to be de-activated and normal op-
eration to proceed.

NOTE When the FIA T CODE anti-theft system is present, it is extremely inadvisable to test the vehicle
using another engine control unit. In this case, the FIA T CODE control unit would transfer the
recognition code (unknown) to the test control unit, which would thus be rendered completely
unserviceable on other vehicles.

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Fiat barchetta Engine
Fuel system

IGNITION MANAGEMENT

Ignition managementstrategiesservethe purpose of triggering a spark with the required advanceac-

cording to engine operating conditions.
Ignition managementconsists essentiallyof calculating ignition advanceand implementing it by con-
trolling a power module located outside the ECU.
The baseadvance,computed on the basis of intake air flow and engine speed, is subjected to further
correction throughout the engine service range.
The ECU determinesthe instant at which current begins to flow through the coil primary winding ac-
cording to engine rpm.
This instant naturallychangesin relationto the combustionTOCof eachcylinder and is in direct propor-
tion to engine rpm becausethe time (dwell) requiredto saturatethe coil primarywinding with current is
roughly constant.
The instant at which conduction begins is corrected according to battery voltage.

P3W11AJO1

1. Ignition power module earth

2. Ignition power module
3. Single ignition coil (plug-top)
4. Coilsecondarv earth

Coovriaht Fiat Auto 11

Engine Fiat barchetta
Fuel system

Starting

During start-up, normal advancemanage-

ment cannot be applied because consider-
able fluctuations in rpm levels do not permit
accurate calculation of dwell and advance.
Advance is therefore managed by taking the
following as references:
- for start of conduction, tooth at 65°;
- for ignition advance,tooth at 10°.
The result is a fixed advance of 10° for the
entire time the engine is cranked by the
starter motor.

Cold running

An additional advance correction is applied

when the engine is running cold. The ad-
P3W12AJO1
vance increase in relation to the mapped set-
tX: crankshaft phonic wheel signal framework ting is inversely proportional to engine tem-
L\tX: fixed ignition advance (10° engine) perature.
ON: active coil conduction
OFF: inactive coil conduction

Cut-off

Ignition advanceis increased when cut-off comes into operation. The advance is gradually restored to
base level as soon as the fuel supply is restored.

Engine idling

Advance is controlled independently from

the base advance when the engine is idlrng.
The idling advance setting alters according to
coolant temperature (10° with engine warm)
and is corrected according to speed changes
in relation to the set speed, which is also tem-
perature-dependent.
The advance is increased if speed falls and re-
duced if speed rises, in order to ensure speed
stability.

P3W12AJO2

/1(X: ignition advance correction when idling

+/1 RPM: idle speed exceeds rated level
-/1 RPM: idle speed is less than rated level

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Fiat barchetta Engine
Fuel system

Controlling knock

This function detectsthe presenceof knock by processingsignalsfrom relevantsensors.The ECUcon-

tinually comparessignals from sensorswith a threshold level which is continually updated in turn to
take into account background noise and engine age.
If the systemdetects the presenceof knock, the strategy reducesthe ignition advance in 2° steps to a
maximumof 6°, until the phenomenondisappears.The advanceis then gradually restoredto the base
setting or until knock recurs.Advance increasesare implementedgradually, whereas reductions take
place immediately.
When accelerating,a higher threshold is usedto take into account increasedengine noise in these cir-
cumstances.
The knock control strategyis also self-adaptive.This meansthat advancereductions repeatedregularly
are memorisedin order to adjust mappingto the rangeof conditions experiencedby the engine (use of
low-octane fuel, for example).The strategy is able to restorethe advancesetting to the mapped level
when the conditions that gave rise to the reduction cease.

Operation with timing variator activated

The base advance setting is adjusted according to engine speed and load depending on whether or not
the timing variator is active/inactive.

TIMING VARIATOR MANAGEMENT

The ECU controls the hydraulic timing

variator actuator (fitted to camshaft, intake
end) by means of a control relay.
The variator can take up to operating posi-
tions:
1. OFF position (power, reduced engine
and idle load), corresponding to normal
camshaft setting;
2. ON position (torque), corresponding to
a crankshaft advance of 25° over the
camshaft.
The variator is normally in OFF position,
but set to ON according to engine load
and rotating sReed as shown in the figure.
In all cases, ON position is activated only
when coolant temperature exceeds 40°C.

1. Variator in ON position
2. TP power curve (engine load)
3. Maximum speed limitation

Copyright Fiat Auto 13

Engine Fiat barchetta
Fuel system

ENGINE IDLE CONTROL

The main aim of this strategy is to maintain engine speed at around the mapped setting (warm engine:
850 rpm): the position assumed by the actuator is dependent on engine conditionsjrpm and vehicle
speed.

Start-up stage
When the key is inserted, the actuator takes up a position dependent on engine temperature and battery
voltage (open-loop position).

Engine started up with accelerator pedal released

Engine speed varies according to engine temperature and is maintained constantly close to this value by
adjusted plunger position to compensate for speed fluctuations.
This applies particularly when external loads are activated (power steering, heated rear window etc.).
If the fans and air conditioner are activated, both controlled by the ECU, the strategy controls the actua-
tor ahead of actual activation.

Normal running
The actuator is in open-loop position under these conditions.

Over-run
When accelerator pedal is released without the engine idling, the actuator position moves through a
specific output curve (dash-pot curve). In other words, return of the plunger to its seat is slowed to re-
duce engine braking effect.

CARBON FILTER FLUSHING

The strategy controls carbon filter flushing solenoid position as follows:

- because the solenoid remains closed during start-up, this prevents fuel vapours enriching the mixture.
This condition persists until coolant temperature reaches 25°C;
- with the engine warm, the ECU controls the solenoid through its duty cycle in order to control the
amount of fuel vapour sent to the intake, on the basis of engine speed and load.
Under the following operating conditions:
- throttle closed,
- speed less than 1250 rpm,
- TP engine load < 1 ms,
solenoid control is de-activated so that the solenoid is maintained closed.

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Fiat barchetta Engine
Fuel system

HEATING/VENTILATION SYSTEM MANAGEMENT

The Hitachi engine control unit is connected operationally to the air conditioning system because:
1. a
is compressor activation request
taken (supplementary air); from
. the ajc ECU is received through pin 28, and appropriate action
2. compressor activation is enabled via pin 113, when certain pre-established conditions are satisfied;
3. information on 3-level thermostat status is received through pin 17 and appropriate action is taken
(radiator fan activation).
With regard to point 1, if the engine is idling, the ECU increases the flow of air from the idle actuator
ahead of compressor activation while the actuator is restored to normal position with a delay in relation
to compressor de-activation.
With regard to point 2, the ECU automatically controls compressor de-activation:

- for a time of 6 s (timed de-activation):

- with throttle opening in excess of 70°,
- upon vehicle take-off;

- as long as critical conditions persist:

- for coolant temperatures in excess of 114°C,
- for engine speeds less than 750 rpm.

P3W1SAJO1

1. Compressor 4. Battery
2. Compressor control relay 5. Heating/ventilation control unit
3. Fuse box 6. Three stage pressure switch

Copyright Fiat Auto 15

Engine Fiat barchetta
Fuel system

RADIATOR FAN MANAGEMENT

The ECU controls radiator fan operation directly according to coolant temperature and whether the ve-
hicle is fitted with an air conditioning system or not.

NOTE The radiator is no longer fitted with a thermal contact because engine temperature is recorded
by the relevant sensor.

Non-air conditioned version

A single fan is activated when coolant tem-

perature exceeds 95°C.

De-activationoccurs with a hysteresis of 2°C

on the temperature threshold.

1. Fuse

Air conditioned version

Two fans with different operating modes may

be fitted.
- low speed
- high speed

1. Fuse
2. High speed relay
3. Low speed relay
4. Electric fan
5. Electric fan
6. Load resistance

VII:96-' $up~r&:~d~&:pr~v.l.o u &: veT&:.

16 Publication no. 506.586/04