INTRODUCTION - PETROL FUEL INJECTION SYSTEM

2.2

SPECIFICATIONS

Four cylinder in line engine, ignition management with lost spark, 16 valves, twin overhead camshaft, counter-balance shafts, motorized throttle body; equipped with Motorola E16 injection system with PCB technology control unit.

The unit is a system made up of the engine and all circuits required for its operation:

- fuel supply system

- air supply system

- engine cooling system

- exhaust system with catalytic converter built into the exhaust manifold

- fuel vapour recirculation system.

The operation of these systems is optimised by an electronic control system governed by a control unit.

Operation of the injection-ignition system

The Motorola E16 system with a motorized throttle manages the sequential, phased type electronic injection and ignition function.

The control unit controls the air flow rate at the idling speed set by the electronic throttle.

The control unit controls the ignition time, with the benefit of maintaining smooth engine operation even when environmental and applied load parameters and engine operating conditions change.

The control unit controls and manages the injection so that the air/fuel ratio is always close to the stoichiometric ratio to ensure maximum conversion efficiency for the catalytic converter.

The main system functions are essentially as follows:

- self-learning;

- system self-adaptation;

- autodiagnosis on K line;

- reccognition of Fiat CODE (immobilizer) on CAN serial line + W line (redundant line);

- cold starting check control;

- control of combustion - Lambda sensors;

- detonation control;

- control of mixture enrichment during acceleration;

- fuel cut-off during release of accelerator pedal;

- fuel vapour recovery;

- control of maximum rpm;

- fuel pump control;

- climate control system control;

- cylinder position recognition;

- control of optimum injection time for each cylinder;

- adjustment of ignition advance;

- idle speed management (also dependent on battery voltage - electrical balance management function);

- management of throttle opening laws (accelerator pedal - torque request maps);

- fan control with 3 drivers;

- connection with ABS/ASR/VDC control unit;

- cruise control (where fitted);

- connection with the control panel;

- torque management;

EOBD OPERATION

- fuel system diagnostics;

- catalytic converter diagnostics;

- misfire diagnosis; detection of failed combustion;

- Lambda sensor diagnosis (pollution or signal distortion).

Torque control strategy

The drive-by-wire control systems are vital in satisfying the legal requirements such as fuel consumption and emissions as well as for improving the driveability of vehicles with petrol engines (starting, heating, transition response, safe driving).

The torque for petrol engines is mainly affected by the throttle valve which controls the mass of air introduced by the engine, (depending on the position of the accelerator pedal; more precisely, the request for power by the user, coming from the accelerator pedal, does not directly control the opening of the throttle valve, as in traditional systems with mechanical bowden cables, but is processed electronically by the control unit before being implemented by the throttle electric motor), and therefore also the filling of the cylinder.

In addition to this there are other parameters that affect the variation of the engine torque: the ignition angle, the air/fuel (Lambda) radtio, the deactivation of injection for some cylinders.

INJECTION SYSTEM

The essential conditions to be met by the air-fuel mixture for efficient operation of engines with controlled ignition systems are mainly as follows:

- the metering (air/fuel ratio) must be kept as close as possible to stoichiometric levels to assure maximum catalytic converter conversion capacity (max. efficiency).

- the homogeneity of the mixture, consisting of petrol distributed throughout the air as finely and uniformly as possible.

Information that the control unit processes to control optimum metering is received by electrical signals emitted by:

- air flow meter and (built in) air temperature sensor, for the exact quantity of air taken in;

- rpm sensor that generates a sinusoidal signal whose frequency is an indicator of engine rpm.

The control unit uses this signal to detect MISFIRE.

- throttle potentiometer, to recognize the accelerator request conditions (the dual throttle potentiometer is, in reality, a safety feature of the DbW system and has the main function of monitoring the effective position of the throttle valve controlled by the activating motor, in particular during the management of possible fault conditions and the implementation of recovery strategies).

The torque request information by the driver is recognized by the control unit by means of the accelerator pedal dual potentiometer.

- coolant temperature sensor on the thermostat;

Lambda sensors to determine the oxygen content of the exhaust gases and, via the downstream sensor, to diagnose the efficiency of the catalytic converter.

IGNITION SYSTEM

The ignition system is the static, inductive discharge type (i.e. without a HT distributor) with the power module located inside the DIS (external ignition module).

The ignition system ensures that each coil supplies cylinders 1-4 and 2-3, respectively (lost spark system).

The advantages of this solution are:

- lower electrical overload;

- guaranteed constant discharge at each spark plug.

The control unit contains a memory map with a set of optimum ignition advance values (for the cylinder in combustion phase) that the engine can adopt according to the required speed and engine load.

The control unit corrects the advance value mainly on the basis of:

- engine coolant temperature

- intake air temperature

- detonation.

- throttle valve position.

Information that the control unit processes to control the coils is received by electrical signals emitted by:

- air flow meter and air temperature sensor, for the exact quantity of air taken in;

- rpm sensor that generates an alternating single-phase signal whose frequency is an indicator of engine rpm;

detonation sensor (on the rear part of the crankcase between cylinders 2 and 3) to recognise the cylinder with knock and thus correct the ignition advance;

- throttle position potentiometer to recognise minimum, partial and full load conditions.

DIAGRAM SHOWING INFORMATION ENTERING/LEAVING THE CONTROL UNIT

1. Injectors

2. Fuel pump

3. Air conditioning compressor

4. Solenoid valve with 3 drivers

5. Cruise control lever

6. Lambda sensor downstream of the catalytic converter

7. Air conditioning system freon pressure linear sensor

8. Brake pedal switch

9. Absolute pressure sensor (MAP)

10. Speedometer signal detected by CAN

11. Lambda sensor upstream of the catalytic converter

12. Coolant temperature sensor

13. Detonation sensor

14. Rpm sensor

15. Accelerator pedal potentiometer

16. Air flow meter with built in air temperature sensor

17. Battery

18. Clutch pedal switch

19. Motorized throttle body

20. CAN line

21. Fiat CODE (on CAN and on redundant W line)

22. Diagnostic socket

23. Fuel vapour recirculation solenoid valve

24. Ignition coils and external power module

25. Injection warning light

26. Oil pressure switch

27. Oil level switch

28. Engine rpm signal detected by CAN

SYSTEM OPERATING LOGICS

Self-learning

The control unit implements the self-learning logic in the following conditions:

- removing-refitting or replacement of the injection control unit;

- removing-refitting or replacing the integrated throttle casing;

- removal-refitting or replacement of the rpm sensor/phonic wheel for detection of misfiring.

System self-adjustment

The control unit is equipped with a self-adjustment function that is designed to recognize the changes that take place in the engine due to the processes of bedding in and ageing of both the components and the engine itself in time.

These changes are memorized in the form of modifications to the basic map and are designed to adapt the operation of the system to the gradual alterations in the engine and the components compared with when they were new.

This self-adjustment function also makes it possible to compensate for the inevitable differences in any replacement components (due to production tolerances).

The control unit modifies the basic map in relation to engine specifications when new on the basis of an exhaust gas analysis.

The self-adjustment parameters are not deleted if the battery is disconnected.

Self-diagnosis

The control unit auto-diagnostic system checks that the system is working properly and signals any irregularities by means of an (MIL) warning light in the instrument panel with a standardized ideogram and colour laid down by European regulations. This warning light indicates engine management faults and also faults detected by EOBD diagnostic strategies.

The MIL warning light operating (MIL) strategy is as follows:

- with the ignition on, the warning light comes on and remains on until the engine has been started up. The control unit self-diagnostic system checks the signals coming from the sensors comparing them with the permitted limits.

Fault indication during start up:

- the failure of the warning light to go out when the engine has been started indicates that there is an error memorized in the control unit.

Fault indication during operation:

- the warning light comes on in flashing mode to indicate possible catalytic converter damage due to misfiring.

- the warning light comes on in constant mode to indicate the presence of engine management or EOBD diagnostic errors.

Not all faults lead to the MIL EOBD warning light coming on. The effective presence of faults should be checked by reding the control unit errors memory with the diagnostic socket on the K line.

Recovery

From time to time the control unit defines the type of recovery according to the components that are faulty.

The recovery parameters are managed by components that are not faulty.

Fiat code recognition

The moment the control unit receives the ignition ON signal it converses with the Fiat CODE control unit (via the body computer on the CAN serial line; if there are failure conditions on the line, the dialogue takes place on the W line) to obtain the go ahead for starting.

Cold starting control

The following occurs in cold starting conditions:

- a natural weakening of the mixture as a result of poor evaporation of the fuel at low temperatures;

- fuel condensation on inner walls of the intake manifold;

- increased lubrication oil viscosity.

The electronic control unit detects this condition and corrects the injection time on the basis of:

- coolant temperature;

- intake air temperature;

- battery voltage;

- engine rpm.

The ignition advance is determined solely on the basis of rpm and coolant temperature.

Whilst the engine is warming up, the control unit operates the motorized throttle to regulate the quantity of air required to ensure that the engine does not cut out.

The rotation speed decreases proportionally as the engine temperature increases until the nominal value is reached when the engine has warmed up.

Control of combustion - lambda sensors

In EOBD systems, the Lambda sensors are all the same type and located upstream of the catalytic conversion system and downstream of the converter. The upstream sensors monitor concentration and are known as the 1st loop (closed loop of upstream sensor). The sensor downsream of the catalytic converter is used for the fault diagnosis of the catalytic converter (in the Motoroal system the downstream sensor is only used to carry out the catalytic converter fault diagnosis).

Control of detonation

The control unit detects the presence of detonation (engine knock) by processing the signal coming from the relevant sensor.

The control unit continuously compares the signals coming from the sensor with a threshold which is, in turn, continually updated to take into account background noise and engine ageing.

The control unit is therefore capable of detecting the presence of detonation (or the onset of detonation) in each individual cylinder and reduces the ignition advance in the cylinder involved (in steps of 3° up to a maximum of 6°) until the phenomenon disappears. Later on, the advance is gradually restored to the basic value (in steps of 0.8°).

In acceleration conditions, a higher threshold is used to take into account the increased noise of the engine in these circumstances.

The detonation control logic also has a self-adjustment function which memorizes the reductions in the advance that are continuously repeated in order to adapt the map to the different conditions that the engine finds itself in.

Control of enrichment during acceleration

If, during the acceleration request, the variation in the air flow meter signal exceeds a pre-set level, the control unit increases the injection (time) to compensate for the variation in the mixture ratio due to the increased pressure in the intake manifold (less fuel evaporation): this allows the required engine speed to be reached quicker.

Recovery

The control unit replaces the signal coming from the air flow meter which is faulty with the throttle potentiometer signal.

Fuel cut off during deceleration

When the accelerator pedal is released and beyond a pre-set engine speed level, the control unit:

- cuts off the supply to the injectors

- reactivates the supply to the injectors at 1300 - 1500 rpm

If there is no supply, the number of revs decreases with the speed depending on the vehicle driving conditions.

Before the idle speed is reached, the progress of the engine speed decrease is checked.

If it is above a certain value, the fuel supply is partly restored so that there is a "gentle accompaniment" towards the idle speed.

The levels for restoring the supply and for cutting off the fuel vary according to:

- engine coolant temperature;

- vehicle speed;

- engine rpm.

Fuel vapour recovery

Fuel vapours (pollutants) collected in the activated carbon filter (canister) are directed to the intake ports to be burnt.

This takes place by means of a solenoid valve controlled by the control unit only when the engine operating conditions allow.

The control unit compensates for this additional amount of fuel with a reduction in the supply to the injectors.

Control of the maximum revs

According to the rpm level reached by the engine, the control unit:

- above 6800 rpm, cuts off the supply to the injectors (a maximum of 7200 rpm can be reached for not more than 3 secs.).

- below 6800 rpm, injector operation is resumed.

Control of fuel supply - electric fuel pump

The control unit supplies the pump:

- with the ignition ON for 5 secs.;

- with the ignition in AVV and the engine speed > 228 rpm

The control unit cuts off fuel supply to pump:

- with the ignition key in the OFF position;

- with the engine speed < 228 rpm.

The returnless fuel supply system ensures a constant pressure of 3.8 bar.

Connection with the climate control system

When there is a request for power, due to the compressor being switched on, the control unit adjusts the air flow rate with the advantage of maintaining optimum driveability.

The control unit momentarily cuts off the supply to the compressor:

- during starting

- over 6200 rpm

- engine temperature > 112°C.

- during take off with the accelerator fully depressed.

Recognition of cylinder position

During each revolution of the engine the control unit recognizes which cylinder is in the explosion stroke through the timing information coming from the external ignition module and controls the injection and ignition sequence for the appropriate cylinder.

If there is no timing sensor signal, the control unit maintains the phased injection with the vehicle moving.

Adjustment of injection times

The control unit calculates the injector opening time and controls them with extreme precision and speed depending on the:

- rpm;

- air flow rate;

- battery voltage;

- engine coolant temperature.

Adjustment of ignition advances

Thanks to a map stored in its memory, the control unit is capable of calculating the ignition advance depending on:

- the engine load (minimum, partial, full, according to the number of revs and the air flow rate);

- the intake air temperature.

Control of engine cooling fan

Depending on the temperature of the coolant, the control unit controls the engagement of the fan.

There are 4 possible speeds (depending on an internal map).

There is a further control (air conditioning system freon pressure analogue signal from the linear sensor) which switches on the fan in accordance with a memoized table depending on the pressure of the refrigerant gas with the air conditioning system on.

When no coolant temperature signal is present, the control unit implements the recovery function by activating the fan at the maximum speed until the error disappears.

Connection with gearbox control unit (version with aisin transmission)

Communication between the injection-igntion and the gearbox control unit takes place via the CAN line available to both control units.

If there is a gear change (signalled by the gearbox control unit), the control unit reduces the engine torque by:

- reducing the ignition advance

- reducing the throttle opening angle.

Recovery

if the CAN line is faulty, the injection-ignition control unit does not make the torque reductions requested by the gearbox.

The gearbox control unit implements a specific recovery logic.

INJECTION-IGNITION SYSTEM COMPONENTS

Injection-ignition control unit

The control unit is fitted on the engine and withstands high temperatures.

The control unit memory is the flash EPROM type, i.e. it can be reprogrammed from the outside without affecting the hardware. The adoption of the Fiat CODE (key check via the Body Computer) means that control units cannot be swapped between vehicles.

The replacement of the injection control unit with D.V.E. does not require any specific procedure controlled by the diagnostic equipment for the learning of the motorized throttle body, but it does require the self-learning procedure to be carried out for the phonic wheel "CASE LEARN" for EOBD misfire using the appropriate diagnostic equipment control.

Control unit pin out

A1 - Main relay (power supply for injector and power module)

A2 - Not connected

A3 - Not connected

A4 - Not connected

A5 - CAN-H line

A6 - CAN-L line

A7 - Climate control system linear sensor signal

A8 - Not connected

A9 - Not connected;

A10 - Not connected

A11 - Not connected

A12 - Potentiometer signal - accelerator pedal 1

A13 - Potentiometer signal - accelerator pedal 2

A14 - Not connected

A15 - Not connected

A16 - Not connected

A17 - Fan 1st speed operation

A18 - Climate control system linear sensor negative

A19 - Power supply +15/54

A20 - Power supply +30 permanent

A21 - Not connected

A22 - Clutch pedal switch

A23 - Not connected

A24 - Injection system failure warning light (EOBD)

A25 - Cruise Control ON/OFF

A26 - W line

A27 - Brake pedal switch (n.c. side)

A28 - Cruise Control Resume

A29 - Power supply for accelerator pedal potentiometer track 1

A30 - Not connected

A31 - Not connected

A32 - Not connected

A33 - Fan 2nd speed control

A34 - negative for accelerator pedal potentiometer 1

A35 - Cruise Control SET +

A36 - Cruise Control SET -

A37 - CAN-H line

A38 - Brake lights brake pedal switch (n.a. side)

A39 - CAN-L line

A40 - Not connected

A41 - Climate control system linear sensor positive

A42 - Not connected

A43 - Not connected

A44 - Power supply for potentiometer track 2

A45 - Not connected

A46 - Climate control sysem user request switch

A47 - Not connected

A48 - Power supply downstream of main relay

A49 - Not connected

A50 - Negative for potentiometer track 2

A51 - Fuel supply pump

A52 - Not connected

A53 - Not connected

A54 - Engine oil level switch signal

A55 - Not connected

A56 - Not connected

A57 - Not connected

A58 - Not connected

A59 - K line

A60 - Not connected

A61 - Fan 3rd speed operation

A62 - Not connected

A63 - Not connected

A64 - Power supply downstream of main relay

B1 - Not connected

B2 - Not connected

B3 - Not connected

B4 - Detonation sensor (negative side)

B5 - Upstream Lambda sensor signal positive

B6 - Upstream Lambda sensor signal negative

B7 - Downstream Lambda sensor signal positive

B8 - Engine coolant temperature sensor.

B9 - Not connected

B10 - Air temperture sensor incorporated in the flow meter (signal)

B11 - Not connected

B12 - Absolute pressure sensor (signal)

B13 - Coil control signal for cylinders 2-3

B14 - Not connected

B15 - Engine oil pressure switch

B16 - Not connected

B17 - Petrol vapour recovery valve

B18 - CAM timing information coming from external ignition module

B19 - Downstream Lambda sensor signal negative

B20 - Not connected

B21 - Not connected

B22 - Not connected

B23 - Rpm sensor negative

B24 - Not connected

B25 - Motorized throttle potentiometer signal 2

B26 - Rpm sensor positive

B27 - Coil control signal for cylinders 1-4

B28 - Motorized throttle potentiometer signal 1

B29 - Flow meter signal

B30 - Motorized throttle potentiometer positive 1

B31 - Motorized throttle potentiometer positive 2

B32 - Absolute pressure sensor in intake manifold positive

B33 - Cylinder 1 injector control

B34 - Motorized throttle potentiometer negative 1

B35 - Motorized throttle potentiometer negative 2

B36 - Not connected

B37 - Detonation sensor

B38 - Engine coolant temperature sensor (negative side)

B39 - Not connected

B40 - Not connected

B41 - Not connected

B42 - Absolute pressure sensor negative

B43 - Not connected

B44 - Not connected

B45 - Not connected

B46 - Motorized throttle closing control

B47 - Motorized throttle opening control

B48 - Not connected

B49 - Cylinder 2 injector control

B50 - Cylinder 4 injector control

B51 - Cylinder 3 injector control

B52 - Not connected

B53 - Not connected

B54 - Not connected

B55 - Not connected

B56 - Not connected

B57 - Upstream lambda sensor heater control

B58 - Air temperture sensor incorporated in the flow meter (negative side)

B59 - Not connected

B60 - Not connected

B61 - Not connected

B62 - Downstream lambda sensor heater control

B63 - Motorized throttle closing control

B64 - Motorized throttle opening control

Injectors

The injectors are the twin jet type and are fitted on the injector carrier manifold. A safety clip secures the injectors to the manifold and two o-rings assure the seal.

The injectors are responsible for delivering the required amount of fue to the engine. They are devices with open/closed operation, therefore they let the fuel pass if open. The opening time and consequently the amount of fuel injected are decided by the engine management control unit.

Accelerator pedal potentiometer

The sensor consists of a casing secured to the accelerator pedal; the case contains an axially-located shaft connected to two potetiometers: a main potentiometer and a stand-by potentiometer.

A coil spring on the shaft ensures the correct amount of resistance to pressure while a second spring ensures return following release.

The accelerator pedal position is converted into an electrical voltage signal and sent to the control unit by the potentiometer connected to the pedal. The accelerator pedal position signal is processed together with the information relating to the engine rpm to obtain the injection times and the position of the motorized throttle.

Insufficient oil pressure sensor

The sensor is located on the crankcase near the oil filter. The control unit controls the signal which is used for:

- showing the message in the multifunction display;

- switching on the warning light in the panel.

It does not switch the MIL warning light on.

Absolute pressure sensor

This sensor is fitted on the intake manifold and controls the pressure of the air introduced into the cylinders. Together with the flow meter signal it is designed to check the right amount of air destined for the individual cylinders for the correct calculation of the air fuel ratio.

Engine coolant temperature sensor.

It is fitted on the thermostatic cup and incorporates the sensitive elements (2 NTC) in a single body which tranform the variations in temperature into variations in resistance thereby allowing the temperature of the engine coolant to be measured.

The sensor is designed using semiconductor technology. In other words, if the temperature of the sensor increases as the temperature of the coolant increases, the resistance value decreases.

Because the resistance does not change in linear fashion as the temperature increases, it is relatively higher at low temperatures than at high temperatures.

The following functions are involved with the sensor:

- information on the temperature of the coolant to the engine management control unit;

- information for the instrument panel to provide a reading for the driver.

The NTCs connect the sensor casing to an insulated earth therefore the sensor has a four-way electrical connection.

The engine coolant temperature sensor also informs the climate control system control unit.

Detonation sensor

The piezoresistive type detonation sensor is fitted on the crankcase between and measures the intensity of vibrations caused by knock in the combustion chambers.

The piezoresistant crystal in the sensor detects vibrations generated at frequencies between 12 and 16 Hz and converts them to electrical signals that are sent to the injection control unit.

Rpm sensor

The sensor is fitted on the cylinder block/crankcase facing the flywheel on the crankshaft.

Operation

The sensor takes the form of a tubular case (1) containing a permanent magnet (3) and an electrical winding (2).

Due to the passage of the phonic wheel teeth, the magnetic flux set up by magnet (3) undergoes fluctuations due to changes in the gap.

These fluctuations set up an electromotive force in winding (2) and a voltage is set up at the terminals that is alternatively positive (tooth facing sensor) and negative (gap facing sensor).

The rpm sensor peak output voltage depends, all else being equal, on the distance between the sensor and the phonic wheel teeth (gap).

Throttle casing with d.v.l.

This is fitted on the air chamber and regulates the amount of air taken in by the engine.

According to the signal received from the accelerator pedal potentiometer, the engine management control unit controls the throttle opening by means of a direct current motor built into the integrated throttle body with D.V.L.

Throttle opening takes place from 0° to 80°, i.e. including idle speed adjustment range.

The DVL integrated throttle body is equipped with two built-in potentiometers, each of which controls the other.

If both potentiometers should fail or in the case of a power cut, the control unit reduces drive torque on the basis of accelerator pedal position.

- with the accelerator pedal fully depressed, it cuts off fuel to one or more cylinders until a maximum speed of 2500 rpm is reached;

- in the intermediate positions, it cuts off the supply to one or more cylinders until a speed below 2500 rpm is reached.

The self-learning procedure must be carried out if the injection control unit or the air chamber or the throttle casing integrated with D.V.L, is replaced.

Air flow meter

The flow meter has the function of measuring the mass of air in the intake manifold; it also includes an air temperature sensor for adapting the calculation to the actual density of the intake air.

D.i.s. module

It forms an integral part of the engine management system.

The two primary windings are engaged and de-energized by means of the ignition phases in the engine management control unit. The secondary windings supply the pairs of cylinders 1-4 and 2-3 simultaneously. When the engine is started injection and ignition takes place in the third cylinder. The ignition voltage required for the cylinder with the mixture ready is greater (10-25 kV) than that for the cylinder in the exhaust stroke (5 kV). This determines the direction of the current between the two spark plugs. Therefore the ignition module recognizes the direction of the current and co-ordinates the injection impulse for the respective cylinder. The sensor involved replaces the timing sensor. If this sensor is faulty, the injection impulse is sent simultaneously for both cylinders.

This module recognizes the ignition phase, in other words the moment the spark strikes at the spark plug in a given cylinder on the basis of the electrical absorption detected by the control unit for the spark plugs.

1.8

SPECIFICATIONS

4 cylinder in line engine, sequential, phased type integrated injection and ignition system 16 valves, dual overhead camshaft, continuous adjustment through phase transformer, motorized throttle body; equipped with Simtec 75.3 injection system and control unit produced by Siemens VDO.

The unit is a system made up of the engine and all circuits required for its operation:

- fuel supply system

- air supply system

- engine cooling system

- exhaust system with catalytic converter built into the exhaust manifold

- fuel vapour recirculation system.

The operation of these systems is optimised by an electronic control system governed by a control unit.

1. Fuel vapour flow enablement solenoid valve

2. Single fuel manifold

3. Ignition coil module

4. Radiator

5. Air flow meter

6. Injection/ignition control unit

7. Throttle body

8. Fuel filter

9. Detonation sensor

10. Rpm sensor

11. Coolant temperature sensor on radiator

12. Spark plugs

13. Upper Lambda sensor

14. Lower Lambda sensor

15. Diagnostic connector

16. EOBD warning light

17. Oil level sensor

18. Oil pressure switch

19. Accelerator pedal

20. Starter motor

21. Fuel tank

22. Fuel pressure regulator

23. Air filter

24. Catalytic converter

25. Activated charcoal filter (canister)

26. Timing sensor

27. Variable geometry chamber solenoid valve

28. Phase transformer solenoid valve

29. Electrical thermostat adjustment

30. Injector

Operation of the injection-ignition system

The Simtec 75.3 system with a motorized throttle manages the sequential, phased type electronic injection and ignition function.

The control unit controls the air flow rate at the idling speed set by the electronic throttle.

The control unit controls the ignition time, with the benefit of maintaining smooth engine operation even when environmental and applied load parameters and engine operating conditions change.

The control unit controls and manages the injection so that the air/fuel ratio is always close to the stoichiometric ratio to ensure maximum conversion efficiency for the catalytic converter.

The main system functions are essentially as follows:

- self-learning;

- system self-adaptation;

- autodiagnosis on K line;

- recognition of Fiat CODE (Immobilizer) on the CAN serial line;

- cold starting check control;

- control of combustion - Lambda sensors;

- check on phase transformers and modular intake manifold;

- detonation control;

- control of mixture enrichment during acceleration;

- fuel cut-off during release of accelerator pedal;

- fuel vapour recovery;

- control of maximum rpm;

- fuel pump control;

- climate control system control;

- cylinder position recognition;

- control of optimum injection time for each cylinder;

- adjustment of ignition advance;

- idle speed management (also dependent on battery voltage - electrical balance management function);

- management of throttle opening laws (accelerator pedal - torque request maps);

- 3 speed fan control;

- connection with ABS/ASR/VDC control unit;

- cruise control (where fitted);

- connection with the control panel;

- torque management;

- control of engine coolant temperature by means of electrically adjusted thermostat

EOBD OPERATION:

- fuel system diagnostics;

- catalytic converter diagnostics;

- misfire diagnosis; detection of failed combustion;

- Lambda sensor diagnosis (pollution or signal distortion).

Torque control strategy

The drive-by-wire control systems are vital in satisfying the legal requirements such as fuel consumption and emissions as well as for improving the driveability of vehicles with petrol engines (starting, heating, transition response, safe driving).

The torque for petrol engines is mainly affected by the throttle valve which controls the mass of air introduced by the engine, (depending on the position of the accelerator pedal; more precisely, the request for power by the user, coming from the accelerator pedal, does not directly control the opening of the throttle valve, as in traditional systems with mechanical bowden cables, but is processed electronically by the control unit before being implemented by the throttle electric motor), and therefore also the filling of the cylinder.

In addition to this there are other parameters that affect the variation of the engine torque: the ignition angle, the air/fuel (Lambda) radtio, the deactivation of injection for some cylinders.

INJECTION SYSTEM

The essential conditions to be met by the air-fuel mixture for efficient operation of engines with controlled ignition systems are mainly as follows:

- the metering (air/fuel ratio) must be kept as close as possible to stoichiometric levels to assure maximum catalytic converter conversion capacity (max. efficiency).

- the homogeneity of the mixture, consisting of petrol distributed throughout the air as finely and uniformly as possible.

Information that the control unit processes to control optimum metering is received by electrical signals emitted by:

- air flow meter and (built in) air temperature sensor, for the exact quantity of air taken in;

- rpm sensor, which produces the digital signals created by the variations in the magnetic field (Hall effect).

The control unit uses this signal to detect MISFIRE.

- throttle potentiometer, to recognize the accelerator request conditions (the dual throttle potentiometer is, in reality, a safety feature of the DbW system and has the main function of monitoring the effective position of the throttle valve controlled by the activating motor, in particular during the management of possible fault conditions and the implementation of recovery strategies).

The torque request information by the driver is recognized by the control unit by means of the accelerator pedal dual potentiometer.

- coolant temperature sensors located on the thermostat and the radiator outlet;

- Lambda sensors to determine the oxygen content of the exhaust gases and, via the downstream sensor, to diagnose the efficiency of the catalytic converter.

IGNITION SYSTEM

The ignition system is the static, inductive discharge type (i.e. without a high tension distributor).

The ignition system has a single coil for each spark plug with an intergrated power stage.

The advantages of this solution are:

- lower electrical overload;

- guaranteed constant discharge at each spark plug.

The control unit contains a memory map with a set of optimum ignition advance values (for the cylinder in combustion phase) that the engine can adopt according to the required speed and engine load.

The control unit corrects the advance value mainly on the basis of:

- engine coolant temperature

- intake air temperature

- detonation.

- throttle valve position.

Information that the control unit processes to operate the single coils is received by electrical signals emitted by:

- air flow meter and air temperature sensor, for the exact quantity of air taken in;

- rpm sensor;

- detonation sensor (on the rear part of the crankcase between cylinders 2 and 3) to recognise the cylinder with knock and thus correct the ignition advance;

- throttle position potentiometer to recognise minimum, partial and full load conditions.

- timing sensors.

The control unit uses the rpm signal to recognize misfiring that could damage the catalytic converters.

DIAGRAM SHOWING INFORMATION ENTERING/LEAVING THE CONTROL UNIT

1. Injectors

2. Fuel pump

3. Air conditioning compressor

4. 3 speed fan

5. Cruise control lever

6. Lambda sensor downstream of the catalytic converter

7. Phase transformer solenoid valve

8. Air conditioning system freon pressure linear sensor

9. Brake pedal switch

10. Timing sensor

11. Speedometer signal detected by CAN

12. Lambda sensor upstream of the catalytic converter

13. Coolant temperature sensor (on the radiator)

14. Coolant temperature sensor (on the thermostat)

15. Detonation sensor

16. Rpm sensor

17. Accelerator pedal potentiometer

18. Air flow meter with built in air temperature sensor

19. Battery

20. Clutch pedal switch

21. Motorized throttle body

22. CAN line

23. Fiat CODE (on CAN and on redundant W line)

24. Diagnostic socket

25. Fuel vapour recirculation solenoid valve

26. Resistance for electrically controlled thermostat

27. Ignition coils and external power module

28. Injection warning light

29. Oil pressure switch

30. Oil level switch

31. Engine rpm signal detected by CAN

SYSTEM OPERATING LOGICS

Self-learning

The control unit implements the self-learning logic in the following conditions:

- removing-refitting or replacement of the injection control unit;

- removing-refitting or replacing the integrated throttle casing;

System self-adjustment

The control unit is equipped with a self-adjustment function that is designed to recognize the changes that take place in the engine due to the processes of bedding in and ageing of both the components and the engine itself in time.

These changes are memorized in the form of modifications to the basic map and are designed to adapt the operation of the system to the gradual alterations in the engine and the components compared with when they were new.

This self-adjustment function also makes it possible to compensate for the inevitable differences in any replacement components (due to production tolerances).

The control unit modifies the basic map in relation to engine specifications when new on the basis of an exhaust gas analysis.

The self-adjustment parameters are not deleted if the battery is disconnected.

Self-diagnosis

The control unit auto-diagnostic system checks that the system is working properly and signals any irregularities by means of an (MIL) warning light in the instrument panel with a standardized ideogram and colour laid down by European regulations. This warning light indicates engine management faults and also faults detected by EOBD diagnostic strategies.

The MIL warning light operating (MIL) strategy is as follows:

- with the ignition on, the warning light comes on and remains on until the engine has been started up. The control unit self-diagnostic system checks the signals coming from the sensors comparing them with the permitted limits.

Fault indication during start up:

- the failure of the warning light to go out when the engine has been started indicates that there is an error memorized in the control unit.

Fault indication during operation:

- the warning light comes on in flashing mode to indicate possible catalytic converter damage due to misfiring.

- the warning light comes on in constant mode to indicate the presence of engine management or EOBD diagnostic errors.

Not all faults lead to the MIL EOBD warning light coming on. The effective presence of faults should be checked by reding the control unit errors memory with the diagnostic socket on the K line.

Recovery

From time to time the control unit defines the type of recovery according to the components that are faulty.

The recovery parameters are managed by components that are not faulty.

Fiat code recognition

The moment the control unit receives the ignition ON signal it converses with the Fiat CODE control unit via the body computer on the CAN serial line to obtain the go ahead for starting.

Cold starting control

The following occurs in cold starting conditions:

- a natural weakening of the mixture as a result of poor evaporation of the fuel at low temperatures;

- fuel condensation on inner walls of the intake manifold;

- increased lubrication oil viscosity.

The electronic control unit detects this condition and corrects the injection time on the basis of:

- coolant temperature;

- intake air temperature;

- battery voltage;

- engine rpm.

The ignition advance is determined solely on the basis of rpm and coolant temperature.

Whilst the engine is warming up, the control unit operates the motorized throttle to regulate the quantity of air required to ensure that the engine does not cut out.

The rotation speed decreases proportionally as the engine temperature increases until the nominal value is reached when the engine has warmed up.

Control of combustion - lambda sensors

In EOBD systems, the Lambda sensors are all the same type and located upstream of the catalytic conversion system and downstream of the converter. The upstream sensors monitor concentration and are known as the 1st loop (closed loop of upstream sensor). The sensor downsream of the catalytic converter is used for the fault diagnosis of the catalytic converter (in the Simtec 75.3 system the downstream sensor is only used to carry out the catalytic converter fault diagnosis).

Control of the phase transformer and modular intake manifold

In order to ensure the optimum quantity of air introduced by the engine, the control unit controls:

- continuous inlet and exhaust timing;

- the geometry of the intake manifolds in two lengths.

At maximum torque the control unit controls the intake manifold in the the long duct position.

At maximum power and idle the control unit controls the intake manifold in the short duct position.

In all other engine operating conditions, the control unit selects the most suitable configuration for optimum performance, consumption and emissions.

Control of detonation

The control unit detects the presence of detonation (engine knock) by processing the signal coming from the relevant sensor.

The control unit continuously compares the signals coming from the sensor with a threshold which is, in turn, continually updated to take into account background noise and engine ageing.

The control unit is therefore capable of detecting the presence of detonation (or the onset of detonation) in each individual cylinder and reduces the ignition advance in the cylinder involved (in steps of 3° up to a maximum of 6°) until the phenomenon disappears. Later on, the advance is gradually restored to the basic value (in steps of 0.8°).

In acceleration conditions, a higher threshold is used to take into account the increased noise of the engine in these circumstances.

The detonation control logic also has a self-adjustment function which memorizes the reductions in the advance that are continuously repeated in order to adapt the map to the different conditions that the engine finds itself in.

Control of enrichment during acceleration

If, during the acceleration request, the variation in the air flow meter signal exceeds a pre-set level, the control unit increases the injection (time) to compensate for the variation in the mixture ratio due to the increased pressure in the intake manifold (less fuel evaporation): this allows the required engine speed to be reached quicker.

Recovery

The control unit replaces the signal coming from the air flow meter which is faulty with the throttle potentiometer signal.

Fuel cut off during deceleration

When the accelerator pedal is released and beyond a pre-set engine speed level, the control unit:

- cuts off the supply to the injectors

- reactivates the supply to the injectors at 1400 - 1500 rpm

If there is no supply, the number of revs decreases with the speed depending on the vehicle driving conditions.

Before the idle speed is reached, the progress of the engine speed decrease is checked.

If it is above a certain value, the fuel supply is partly restored so that there is a "gentle accompaniment" towards the idle speed.

The level for restoring the supply and for cutting off the fuel varies according to:

- engine coolant temperature;

- gear engaged;

- engine rpm.

Fuel vapour recovery

Fuel vapours (pollutants) collected in the activated carbon filter (canister) are directed to the intake ports to be burnt.

This takes place by means of a solenoid valve controlled by the control unit only when the engine operating conditions allow.

The control unit compensates for this additional amount of fuel with a reduction in the supply to the injectors.

Control of the maximum revs

According to the rpm level reached by the engine, the control unit:

- beyond 6500 rpm the throttle is restricted not to exceed this level;

- below 6500 rpm, normal throttle operation is resumed.

Control of fuel supply - electric fuel pump

The control unit supplies the pump:

- with the ignition ON for 3 secs.;

- with the ignition in AVV and the engine speed above 32 rpm

The control unit cuts off fuel supply to pump:

- with the ignition key in the OFF position;

- with the engine speed below 32 rpm.

The returnless fuel supply system ensures a constant pressure of 3.8 bar.

Connection with the climate control system

When there is a request for power, due to the compressor being switched on, the control unit adjusts the air flow rate with the advantage of maintaining optimum driveability.

The control unit momentarily cuts off the supply to the compressor:

- during starting

- over 6000 rpm

- with the engine temperature above 120 °C

- during take off depending on the engine speed, pedal position and vehicle speed.

Recognition of cylinder position

During each engine revolution, the control unit detects the cylinder in combustion phase through the timing sensors: controls the injection and ignition sequence for the appropriate cylinder.

If the timing sensor is faulty, the control unit implements the following strategies:

- with the engine running, it ensures the engine runs correctly due to its memorized cylinder sequence;

- if the engine is turned off and restarted, the ignition is activated for coil pairs with a lost spark. Knock control is deactivated and a fixed delay is applied for all cylinders.

Adjustment of injection times

The control unit calculates the injector opening time and controls them with extreme precision and speed depending on the:

- rpm;

- air flow rate;

- battery voltage;

- engine coolant temperature.

Adjustment of ignition advances

Thanks to a map stored in its memory, the control unit is capable of calculating the ignition advance depending on:

- the engine load (minimum, partial, full, according to the number of revs and the air flow rate);

- the intake air temperature.

Control of engine cooling fan

Depending on the temperature of the coolant leaving the engine and the temperature of the coolant coming out of the radiator, the control unit controls the engagement of the fan, if the engine cooling cannot be managed through the advance opening of the electrically controlled thermostat.

There are 3 possible speeds (depending on an internal map).

There is a further control (air conditioning system freon pressure analogue signal from the linear sensor) which switches on the fan in accordance with a memoized table depending on the pressure of the refrigerant gas with the air conditioning system on.

When no coolant temperature signal is present, the control unit implements the recovery function by activating the fan at the maximum speed until the error disappears.

INJECTION-IGNITION SYSTEM COMPONENTS

Injection-ignition control unit

The control unit is fitted on the intake manifold and withstands high temperatures.

The control unit memory is the flash EPROM type, i.e. it can be reprogrammed from the outside without affecting the hardware. The adoption of the Fiat CODE (key check via the Body Computer) means that control units cannot be swapped between vehicles.

The replacement of the injection control unit does not require any specific procedure using diagnostic equipment for the learning of the motorized throttle body, this procedure takes place automatically at the key-on.

The engine management control unit is a component sensitive to electrostatic interference; avoid touching the control unit with the engine running unless you are wearing suitable clothing or have discharged any static electricity by touching something metal.

The engine compartment contains many moving parts, components at high temperatures and live wires. Follow the warnings given below very carefully when working in the engine compartment: turn off the engine and wait for it to cool down, do not smoke, do not use naked flames and ensure a fire extinguisher is available.

Control unit pin out

Connector A - Engine side (64 pin)

A1 - Coil control signal for cylinder 1

A2 - Coil control signal for cylinder 1

A3 - Modular intake manifold

A4 - Electronic thermostat

A5 - Insufficient engine oil pressure switch (digital input)

A6 - Downstream Lambda sensor earth

A7 - Not connected

A8 - Motorized throttle potentiometer signal 2

A9 - Motorized throttle potentiometer signal 1

A10 - Detonation sensor (positive)

A11 - Downstream Lambda sensor earth

A12 - Intake air temperature signal incorporated in the flow meter

A13 - Not connected

A14 - Linear pressure sensor (negative)

A15 - Not connected

A16 - Not connected

A17 - Coil control signal for cylinder 2

A18 - Coil control signal for cylinder 2

A19 - Downstream lambda sensor heater control

A20 - Not connected.

A21 - Exhaust side timing sensor signal

A22 - Inlet side timing sensor signal

A23 - Upstream Lambda sensor earth

A24 - Inlet side timing sensor negative

A25 - Engine coolant temperature sensor negative (A)

A26 - Exhaust side timing sensor negative

A27 - Detonation sensor negative

A28 - Flow meter negative

A29 - Downstream Lambda sensor earth

A30 - Not connected

A31 - Motorized throttle actuator positive

A32 - Motorized throttle actuator

A33 - Coil control signal for cylinder 3

A34 - Coil control signal for cylinder 3

A35 - Rpm sensor signal

A36 - Engine oil level switch

A37 - Not connected

A38 - Not connected

A39 - Rpm sensor negative

A40 - Motorized throttle potentiometer negative 1

A41 - Motorized throttle potentiometer signal 2

A42 - Inlet side timing sensor positive

A43 - Engine oil level switch negative

A44 - Detonation sensor earth

A45 - Not connected

A46 - Fuel vapour recovery solenoid valve

A47 - Motorized throttle actuator negative

A48 - Motorized throttle actuator negative

A49 - Coil control signal for cylinder 4

A50 - Coil control signal for cylinder 4

A51 - Not connected

A52 - Not connected

A53 - Upstream Lambda sensor positive

A54 - Downstream Lambda sensor positive

A55 - Exhaust side phase transformer actuator

A56 - Inlet side phase transformer actuator

A57 - Not connected

A58 - Upstream Lambda sensor heater

A59 - Flow meter

A60 - Engine coolant temperature sensor signal (A)

A61 - Cylinder 2 injector control

A62 - Cylinder 3 injector control

A63 - Cylinder 4 injector control

A64 - Cylinder 1 injector control

Connector B - Vehicle side (64 pin)

B1 - Injection system failure warning light

B2 - Air conditioning system engagement request

B3 - Engine coolant temperature sensor signal (B) (on radiator)

B4 - Not connected

B5 - K line

B6 - CAN L line

B7 - Not connected

B8 - Not connected

B9 - Not connected

B10 - Engine cooling fan 2nd speed engagement relay

B11 - Not connected

B12 - Not connected

B13 - Not connected

B14 - Not connected

B15 - Not connected

B16 - Clutch pedal switch

B17 - Not connected

B18 - Not connected

B19 - Not connected

B20 - Not connected

B21 - CAN L line

B22 - Not connected

B23 - Sensors power supply

B24 - Motorized throttle potentiometer power supply 1

B25 - Motorized throttle potentiometer power supply 2

B26 - Motorized throttle potentiometer negative 1

B27 - Motorized throttle potentiometer negative 2

B28 - Engine coolant temperature sensor negative (B) (on radiator)

B29 - Not connected

B30 - Not connected

B31 - +30 battery power supply

B32 - +30 battery power supply

B33 - Not connected

B34 - Not connected

B35 - Not connected

B36 - Not connected

B37 - CAN L line

B38 - CAN H line

B39 - Not connected

B40 - Not connected

B41 - Cruise Control ON/OFF

B42 - Cruise Control resume

B43 - Cruise Control SET +

B44 - Cruise Control SET -

B45 - Brake light switch

B46 - Not connected

B47 - +30 battery power supply

B48 - Compressor relay

B49 - Fuel pump relay

B50 - Not connected

B51 - Not connected

B52 - Not connected

B53 - Potentiometer signal - accelerator pedal 2

B54 - Potentiometer signal - accelerator pedal 1

B55 - Not connected

B56 - Air conditioning linear pressure sensor

B57 - Brake light switch

B58 - W line

B59 - Engine cooling fan 1st speed engagement relay

B60 - Not connected

B61 - Engine cooling fan 3rd speed engagement relay

B62 - Main relay

B63 - Not connected

B64 - + 15/54 ignition-operated power supply

Injectors

The injectors are the twin jet type and are fitted on the injector carrier manifold.

Accelerator pedal potentiometer

The sensor consists of a casing secured to the accelerator pedal; the case contains an axially-located shaft connected to two potetiometers: a main one and one safety one.

A coil spring on the shaft ensures the correct amount of resistance to pressure while a second spring ensures return following release.

The accelerator pedal position is converted into an electrical voltage signal and sent to the control unit by the potentiometer connected to the pedal. The accelerator pedal position signal is processed together with the information relating to the engine rpm to obtain the injection times and the position of the motorized throttle.

Insufficient oil pressure sensor

The sensor is located on the crankcase, engine oil dipstick side. The control unit controls the signal which is used for:

- showing the message in the multifunction display;

- switching on the warning light in the panel.

It does not switch the MIL warning light on.

Engine coolant temperature sensors

There are two engine coolant temperature sensors, one fitted on the thermostat and the other on the radiator by the outlet hose.

Both sensors incorporate the sensitive element (1 NTC) in a single body and tranform the variations in temperature into variations in resistance thereby allowing the temperature of the engine coolant to be measured.

The sensor is designed using semiconductor technology. In other words, if the temperature of the sensor increases as the temperature of the coolant increases, the resistance value decreases.

Because the resistance does not change in linear fashion as the temperature increases, it is relatively higher at low temperatures than at high temperatures.

The following functions are involved with the sensor:

- information on the temperature of the coolant coming out of the engine to the engine management control unit;

- information on the temperature of the coolant coming out of the radiator to the engine management control unit;

- information for the instrument panel to provide a reading for the driver.

Reference voltage: 5 Volt

Operating temperature: - 40 ° - + 140 °C

Coolant temperature sensor on the radiator

Coolant temperature sensor on the thermostat

Detonation sensor

The piezoresistive type detonation sensor is fitted on the crankcase between and measures the intensity of vibrations caused by knock in the combustion chambers.

The piezoresistant crystal in the sensor detects vibrations generated at frequencies between 12 and 16 Hz and converts them to electrical signals that are sent to the injection control unit.

Timing sensor

The timing sensor, one for each camshaft, is the Hall effect type where a matching element and a 3 pin connector and a magnet and a signal acquisition circuit are incorporated. There are two sensors, one for each camshaft.

Pin out

1. Signal

2. Earth

3. Power supply

Rpm sensor

The rpm and T.D.C. sensor is incorporated in the flywheel side crankshaft seal.

1. Crankshaft rear seal

2. Magnetized disc (encoder)

3. Crankshaft

4. Rpm and T.D.C. sensor

Operation

The crankshaft position and rpm are not transmitted to the rpm sensor by means of a toothed phonic wheel, but by a disc (encoder) (3) with an externally applied magnetized layer (4).

The inner surface of the encoder contains a projection (7) for positioning it correctly on the crankshaft.

The rpm sensor (5) can be removed from the crankshaft seal by loosening a retaining bolt (6) and detaching the connector for the cable loom from the crankshaft seal. In this way, one of the two components can be replaced, the crankshaft seal or the rpm sensor, independently of the other one.

1. Crankshaft seal lip

2. Outer surface of crankshaft seal

3. Encoder

4. Encoder magnetized track

5. Rpm sensor

6. Rpm sensor retaining bolt

7. Projection for positioning encoder on crankshaft

The encoder magnetized track contains the north and south magnetic poles whose magnetic fields are recorded by the rpm sensor during the rotation of the crankshaft and transformed into rpm values and determining T.D.C. in the engine management control unit.

The recognition of the magnetic fields takes place in accordance with the Hall principle. The rpm sensor sends digital signals to the engine management control unit produced by the variation in the magnetic fields.

1. Rpm sensor

2. Magnetic field track

3. Rubber coating for supporting magnets

In order not to alter the magnetic specifications of the encoder producing a negative effect, it is vital to follow the warnings given below for carrying out work on the encoder.

Maintenance warnings:

- Do not bring into contact with other magnetic fields,

- Do not bring into contact with metal shavings,

- Do not damage the encoder rubber track mechnically,

- Do not drop the encoder.

Throttle casing with d.v.l.

This is fitted on the modular air intake chamber and regulates the amount of air taken in by the engine.

According to the signal received from the accelerator pedal potentiometer, the engine management control unit controls the throttle opening by means of a direct current motor built into the integrated throttle body with D.V.L.

Throttle opening takes place from 0° to 80°, i.e. including idle speed adjustment range.

The DVL integrated throttle body is equipped with two built-in potentiometers, each of which controls the other.

If both potentiometers should fail or in the case of a power cut, the control unit reduces drive torque on the basis of accelerator pedal position.

- with the accelerator pedal fully depressed, it cuts off fuel to one or more cylinders until a maximum speed of 1800 rpm is reached;

- in the intermediate positions, it cuts off the supply to one or more cylinders until a speed below 1800 rpm is reached.

If the throttle body with D.V.L. or the injection control unit or the modular air intake chamber is being replaced, the self-learning procedure takes place automatically at the next key-on.

Pin out

1. Potentiometer signal

2. Potentiometer positive

3. Motorized throttle actuator

4. Potentiometer 2 signal

5. Motorized throttle actuator negative

6. Potentiometer earth

Air flow meter

The flow meter has the function of measuring the mass of air in the intake manifold; it also includes an air temperature sensor for adapting the calculation to the actual density of the intake air.

Pin out

1. Earth

2. Flow meter intake air temperature signal

3. Flow meter signal

4. Power supply

Ignition coils

The ignition circuit is the inductive discharge static type, where the high tension is provided by four coils incorporated in a single element and fitted directly above the spark plugs.

Pin out

1. Coil earth

2. Power supply

3. Cylinder 4 coil control

4. Cylinder 3 coil control

5. Cylinder 2 coil control

6. Cylinder 1 coil control