INTRODUCTION - DIESEL FUEL INJECTION SYSTEM

1.3 Multijet

SPECIFICATIONS

Function

The Magneti Marelli MJD 6F3 Common Rail system is a high pressure electronic injection circuit for fast, direct injection diesel engines.

Its main features are:

- availability of high injection pressures (1400 bar) for the 75 CV version;

- availability of high injection pressures (1600 bar) for the 90 CV version;

- possibility of modulating these pressures between 150 bar and the maximum operating value of 1400 bar for the 75 CV version and 1600 bar for the 90 CV version irrespective of the rotation speed and the engine load;

- ability to work at high engine rpms (up to 5000 rpm in full load conditions);

- injection control precision (injection advance and duration);

- reduction in fuel consumption;

- reduction in emissions.

Main system functions are essentially as follows:

- engine coolant temperature control;

- control of amount of fuel injected;

- idle speed check;

- fuel cut-off during over-run;

- cylinder balance check when idling;

- control of anti-judder function

- exhaust fumes control during acceleration;

- exhaust gas recirculation control (E.G.R.);

- maximum torque limit control;

- maximum speed limit control;

- control of heater plugs;

- control of climate control system activation (where fitted);

- auxiliary fuel pump check;

- cylinder position check for timing;

- main and multiple injection advance check;

- injection pressure closed cycle check;

- electrical balance check;

- IMA injector calibration;

- fuel pressure control;

- Lambda sensor control;

- control of variable geometry compressor (90 CV version);

- engine oil life check.

75 CV version

1. Fuel tank

2. Auxiliary fuel pump

3. Fuel filter

4. Pressure pump

5. Rail

6. Pressure regulator

7. Fuel pressure sensor

8. Injectors

9. Air filter

10. Air flow meter

11. Compressor

12. Intercooler

13. E.G.R. solenoid valve

14. Water/exhaust gas heat exchanger for E.G.R. system.

15. E.G.R. diffuser

16. Excess pressure sensor

17. Rpm sensor

18. Timing sensor

19. Water temperature sensor

20. Minimum engine oil pressure switch

21. Heater plugs

22. Heater plugs control unit

23. Turbocharger

24. Waste gate actuator

25. Catalytic converter

26. Lambda sensor (UEGO)

27. Pedal assembly

28. Injection control unit

90 CV version

1. Fuel tank

2. Auxiliary fuel pump

3. Fuel filter

4. Fuel return manifold

5. Pressure pump

6. Pressure regulator on pump

7. Pressure regulator on rail

8. Rail

9. Fuel pressure sensor on rail

10. Injectors

11. Air filter

12. Air flow meter

13. Compressor

14. Intercooler

15. E.G.R. solenoid valve

16. Water/exhaust gas heat exchanger for E.G.R. system.

17. E.G.R. diffuser

18. Pressure relief and air temperature sensor

19. Rpm sensor

20. Timing sensor

21. Water temperature sensor

22. Minimum engine oil pressure switch

23. Heater plugs

24. Heater plugs control unit

25. Variable geometry turbocharger (VGT)

26. VGT actuator

27. VGT actuator solenoid valve

28. Lambda sensor (UEGO)

29. Catalytic converter

30. Pedal assembly

31. Injection control unit

OPERATION

Operating strategies

Introduction

The Common Rail system makes it possible to carry out two pilot injections before T.D.C. with the advantage of distributing the pressure in the combustion chamber more evenly and reducing the combustion noise typical of direct injection engines and up to two injections after the main injection with the advantage of reducing emissions.

The control unit controls the quantity of fuel injected, regulating the line pressure and injection times.

The control unit processes the following information to control the quantity of fuel to inject:

- engine rpm;

- coolant temperature;

- supercharging pressure;

- air temperature (from flow meter);

- intake air quantity;

- battery voltage;

- diesel pressure;

- accelerator pedal position;

- diesel temperature;

- Lambda signals.

Diagram showing information entering/leaving the control unit

1. Auxiliary electric fuel pump

2. Lambda sensor

3. VGT solenoid valve (for 90 CV version only)

4. Air conditioning compressor (where fitted)

5. E.G.R. solenoid valve

6. Rev counter

7. Cooling fan

8. Heater plugs control unit

9. Twin track accelerator pedal potentiometer

10. Brake pedal switch

11. Clutch pedal switch

12. Fuel temperature sensor

13. Fuel pressure sensor

14. Flow meter

15. Coolant temperature sensor

16. Water in diesel filter sensor

17. Cruise control (where fitted)

18. Pressure relief and air temperature sensor

19. Timing sensor

20. Engine rpm sensor

21. Speedometer

22. Battery

23. Fiat CODE (body computer)

24. Diagnostic socket

25. Fuel pressure regulator on rail

26. Injectors

27. Heater plugs

28. Pressure regulator on the pump (for 90 CV version only)

29. Heater plugs warning light

30. Injection warning light

31. Coolant overheating warning light

32. Water in the fuel filter warning light

33. OIL warning light

Self-diagnosis

The control unit self-diagnostic system checks the signals coming from the sensors comparing them with the permitted limits.

SIGNALLING OF FAULTS DURING STARTING:

- Warning light on until engien started indicates test stage;

- Warning light off after engine starting indicates no fault with components that affect the safety of the system;

- Warning light on with engine running indicates fault.

SIGNALLING OF FAULTS DURING OPERATION:

- Warning light on indicates fault;

- Warning light off indicates no fault with components that affect the safety of the system;

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 body computer via the CODE function to obtain the go ahead for starting.

Fuel temperature control

With the temperature of the fuel at 80 °C measured by the sensor in the diesel filter, the control unit operates the pressure regulator to reduce the line pressure and, if this is not enough, to also reduce the amount of fuel injected.

Engine coolant temperature control

When the engine coolant temperature is above 105 °C, the control unit:

- reduces injected fuel quantity (reduces engine power);

- controls the cooling fan

- switches on the coolant temperature warning light.

Control of amount of fuel injected

On the basis of the signals coming from the sensors and the values stored, the control unit:

- controls the pressure regulator on the rail;

- controls the regulator on the pressure pump to modulate the fuel flow rate (for the 90 CV version only)

- varies the "pilot" injection time in the entire rpm range;

- alters the "main" injection time.

Idle speed check

The control unit processes the signals coming from the sensors and regulates the quantity of fuel injected:

- controls the pressure regulator;

- alters the injector injection times.

Within certain limits the speed takes the battery voltage into account.

Fuel cut-off during deceleration

During the accelerator pedal release stage, the control unit implements the following logics:

- places the injector opening time at zero;

- partly varies the injection time for the injectors before the idle speed is reached;

- controls the fuel pressure regulator.

Idle cylinder balance check

According to the signals received from the sensors, the control unit controls the idle speed torque:

- alters the quantity of fuel injected by the individual injectors (injection time).

Check on irregular operation

The control unit processes the signals received by the various sensors and corrects the quantity of fuel to inject in order to improve driveability reducing shuddering whilst driving by means of the injector opening time.

Exhaust fumes control during acceleration

In order to restrict the fumes during fast transitions, on the basis of the signals received from the accelerator pedal potentiometer, Lambda sensor, flow meter and the engine speed the control unit limits the amount of fuel to be injected by means of:

- the pressure regulator

- the injection time for the injectors.

- E.G.R.

Exhaust gas recirculation control (E.G.R.)

In accordance with EURO 4 pollution control legislation, on the basis of the engine load and the signal from the accelerator pedal potentiometer, the control unit limits the quantity of intake air, implementing the partial intake of exhaust gases, through:

-- the adjustment of the opening of the E.G.R. valve

Maximum torque limit control

According to the rpm level, the control unit calculates the following in pre-defined maps:

- the torque limit;

- the permitted fumes (limit).

It compares this minimum values and corrects them with other parameters:

- coolant temperature;

- engine rpm;

- vehicle speed;

- air temperature.

and controls the quantity of fuel to be injected (pressure regulator - injectors).

Maximum speed limit control

When the engine speed reaches 5200 rpm, the control unit interrupts the operation of the injectors and the supply pressure is consequently reduced.

Heater plugs check

The injection unit, during the following stages:

- starting;

- post-starting;

applies a timer to the glow plug preheating control unit based on engine temperature.

Air conditioning system start of operation check

The control unit operates the climate control compressor:

- switching it on/off when the switch is pressed;

- switching it off momentarily (for a few seconds) in the case of strong acceleration or a request for maximum power.

Auxiliary fuel pump check

Irrespective of the rpm, the control unit:

- supplies the auxiliary fuel pump with the ignition ON;

- cuts off the auxiliary pump supply if the engine is not started within a few seconds.

Cylinder position check

During each revolution of the engine the control unit recognizes which cylinder is in the explosion stroke and controls the injection sequence at the appropriate cylinder.

Pilot injection and main injection advance check

According to the signals coming from the various sensors, including the absolute pressure sensor integrated in the control unit itself, the latter determines the optimum injection point, according to an internal map, based on driving comfort and EURO 4 emission limits.

Injection pressure closed cycle check

Depending on the engine load, determined by processing the signals coming from the various sensors, the control unit operates the regulator on the rail and the regulator on the pressure pump (for the 90 CV version only) to produce an optimum line pressure.

Electrical balance check

According to the battery voltage, the control unit alters the idle speed:

- increases the injector injection times;

- modulates the line pressure.

Fan control

Depending on the temperature of the coolant and the pressure of the refrigerant fluid in the air conditioning system, the control unit controls:

- fan activation at first or second or third speed

Cruise control system check (where fitted)

Depending on the position of the control lever, the control unit directly controls the quantity of fuel injected to control and maintain the vehicle speed memorized.

A warning light on the dashboard activated by the control unit indicates system operation or deactivation status.

The cruise control is temporarily disabled:

- by operating the brake;

- by operating the clutch;

- the resume button returns the stored speed.

The cruise control is not disabled when the accelerator is pressed (e.g. to overtake) and automatically restores the vehicle to the set speed as soon as the accelerator is released.

The ASR function (antispin) takes precedence over cruise control for safety reasons.

1.9 Multijet

SPECIFICATIONS

Function

The Bosch EDC 16C39 Common Rail system is a high pressure electronic injection circuit for fast, direct injection diesel engines.

Its main features are:

- availability of high injection pressure (up to 1350 bar);

- possibility of modulating pressures between 150 bar up to a maximum service pressure of 1350 bar, regardless of engine speed and load;

- ability to work at high engine rpm (up to 6000 rpm);

- injection control precision (injection advance and duration);

- reduction in fuel consumption;

- reduction in emissions.

Main system functions are essentially as follows:

- fuel temperature control;

- engine coolant temperature control;

- control of amount of fuel injected;

- idle speed check;

- fuel cut-off during over-run;

- cylinder balance check when idling;

- control of anti-judder function;

- exhaust fumes control during acceleration;

- exhaust gas recirculation control (E.G.R.);

- maximum torque limit control;

- maximum speed limit control;

- control of heater plugs;

- control of climate control system activation (where fitted);

- auxiliary fuel pump check;

- cylinder position check;

- main and pilot injection advance check;

- injection pressure closed cycle check;

- electrical balance check;

- supercharging pressure control;

- self-diagnosis;

- connection with Fiat CODE control unit (Immobilizer)

1. Fuel tank

2. Auxiliary fuel pump

3. Fuel filter

4. Fuel return manifold

5. Pressure pump

6. Pressure regulator

7. Rail

8. Fuel pressure sensor

9. Injectors

10. Air filter

11. Air flow meter

12. Compressor

13. Intercooler

14. Throttle body

15. E.G.R. solenoid valve

16. Water/exhaust gas heat exchanger for E.G.R. system.

17. E.G.R. diffuser

18. Pressure relief and air temperature sensor

19. Rpm sensor

20. Timing sensor

21. Water temperature sensor

22. Minimum engine oil pressure switch

23. Engine oil level sensor

24. Heater plugs

25. Heater plugs control unit

26. Variable geometry turbine

27. Turbine vane position control actuator

28. Turbo vane actuator control solenoid valve

29. Lambda sensor (UEGO)

30. Catalytic precatalyzer

31. Catalytic converter

32. Pedal assembly

33. Injection control unit

OPERATION

Operating strategies

Introduction

The Common Rail system makes it possible to carry out a pre-injection (pilot injection) before T.D.C. with the advantage of reducing the consequences of the pressure in the combustion chamber and reducing the combustion noise typical of direct injection engines.

The control unit controls the quantity of fuel injected, regulating the line pressure and injection times.

The control unit processes the following information to control the quantity of fuel to inject:

- engine rpm;

- coolant temperature;

- supercharging pressure;

- air temperature;

- intake air quantity;

- battery voltage;

- diesel pressure;

- accelerator pedal position.

Diagram showing information entering/leaving the control unit

1. Auxiliary electric fuel pump

2. Lambda sensor

3. VGT solenoid valve

4. Air conditioning compressor (where fitted)

5. E.G.R. solenoid valve

6. Rev counter

7. Cooling fans

8. Heater plugs control unit

9. Accelerator pedal with built in potentiometer

10. Brake pedal switch

11. Clutch pedal switch

12. Diesel temperature sensor

13. Fuel pressure sensor

14. Flow meter

15. Engine coolant temperature sensor

16. Water in diesel filter sensor

17. Cruise Control (where fitted)

18. Pressure relief and air temperature sensor

19. Timing sensor

20. Engine rpm sensor

21. Speedometer

22. Battery

23. Fiat CODE

24. Diagnostic socket

25. Fuel pressure regulator

26. Injectors

27. Heater plugs

28. Throttle solenoid valve

29. Heater plugs warning light

30. Injection warning light

31. Coolant overheating warning light

32. Water in the fuel warning light

33. OIL warning light

Self-diagnosis

The control unit self-diagnostic system checks the signals coming from the sensors comparing them with the permitted limits.

SIGNALLING OF FAULTS DURING STARTING:

- Warning light on for 4 seconds indicates test stage;

- Warning light off after 4 seconds indicates no fault with components that can alter values set out by pollution control regulations;

- Warning light on after 4 seconds indicates fault.

SIGNALLING OF FAULTS DURING OPERATION:

- Warning light on indicates fault;

- Warning light off after 4 seconds indicates no fault with components that can alter values set out by pollution control regulations.

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.

Fuel temperature control

When the temperature of the fuel, measured by the sensor on the recirculation manifold, is 110°C, the control unit operates the pressure regulator to reduce the line pressure (it does not alter the injection times).

Engine coolant temperature control

When the engine coolant temperature is above 105°C, the control unit:

- reduces injected fuel quantity (reduces engine power);

- controls the cooling fans

- switches on the coolant temperature warning light.

Control of amount of fuel injected

On the basis of the signals coming from the sensors and the values stored, the control unit:

- controls the pressure regulator;

- alters the "pilot" injection time up to 3000 rpm;

- alters the "main" injection time.

Idle speed check

The control unit processes the signals coming from the sensors and regulates the quantity of fuel injected:

- controls the pressure regulator;

- alters the injector injection times.

Within certain limits the speed takes the battery voltage into account.

Fuel cut-off during deceleration

During the accelerator pedal release stage, the control unit implements the following logics:

- cuts off the supply to the injectors;

- partly reactivates the supply to the injectors before the idle speed is reached;

- controls the fuel pressure regulator.

Idle cylinder balance check

According to the signals received from the sensors, the control unit controls the idle speed torque:

- alters the quantity of fuel injected by the individual injectors (injection time).

Check on irregular operation

The control unit processes the signals received by the various sensors and corrects the quantity of fuel to inject in order to improve driveability reducing shuddering whilst driving by means of:

- the pressure regulator

- the injector opening time.

Exhaust fumes control during acceleration

In order to restrict the fumes during fast transitions, on the basis of the signals received from the flow meter and the engine speed the control unit limits the amount of fuel to be injected by means of:

- the pressure regulator

- the injection time.

Exhaust gas recirculation control (E.G.R.)

In accordance with EURO 3 pollution control legislation, on the basis of the engine load and the signal from the accelerator pedal potentiometer, the control unit limits the quantity of intake air, implementing the partial intake of exhaust gases, through:

- the adjustment of the opening of the E.G.R. valve

Maximum torque limit control

According to the rpm level, the control unit calculates the following in pre-defined maps:

- the torque limit;

- the permitted fumes (limit).

It compares this minimum values and corrects them with other parameters:

- coolant temperature;

- engine rpm;

- vehicle speed;

and controls the quantity of fuel to be injected (pressure regulator - injectors).

Maximum speed limit control

Depending on the rpm, the control unit implements two operating strategies:

- at 5000 rpm it cuts off the fuel reducing the line pressure;

- beyond 5400 rpm it deactivates the auxiliary pump and the injectors.

Heater plugs check

During the starting/post-starting stage, the injection control unit: times the operation of the heater plugs control unit depending on the engine temperature.

Air conditioning system start of operation check

The control unit operates the air conditioning compressor:

- switching it on/off when the switch is pressed;

- switching it off momentarily (about 6 secs) in the case of strong acceleration or a request for maximum power.

Auxiliary fuel pump check

Irrespective of the rpm, the control unit:

- supplies the auxiliary fuel pump with the ignition ON;

- cuts off the auxiliary pump supply if the engine is not started within a few seconds.

Cylinder position check

During each revolution of the engine the control unit recognizes which cylinder is in the explosion stroke and controls the injection sequence at the appropriate cylinder.

Main injection advance and operation check

According to the signals coming from the various sensors, including the absolute pressure sensor integrated in the control unit itself, the latter determines the optimum injection point, according to an internal map, based on driving comfort and EURO 3 emission limits.

Injection pressure closed cycle check

On the basis of the engine load, determined by processing the signals from the various sensors, the control unit controls the regulator to produce optimum line pressure.

Electrical balance check

According to the battery voltage, the control unit alters the idle speed:

- increases the injector injection times;

- modulates the line pressure.

VGT variable geometry turbine operation

The control unit processes the signal from the supercharging pressure, at the various engine operating speeds and determines the quantity of fuel to inject:

- controls the pressure regulator;

- alters the injection time;

- regulates the turbine geometry to ensure optimum performance in all operating conditions.

Fan control

Depending on the temperature of the coolant and the pressure of the refrigerant fluid in the air conditioning system, the control unit controls:

- fan activation at first or second speeds.

Check on throttle closing when switching off

In order to prevent the engine shuddering when it is switched off, the control unit controls the immediate closure of the inlet throttle. The throttle remains open in all other operating conditions.

Cruise control system check (where fitted)

Depending on the position of the control lever, the control unit directly controls the quantity of fuel injected to control and maintain the vehicle speed memorized.

A warning light on the dashboard activated by the control unit indicates system operation or deactivation status.

The cruise control is temporarily disabled:

- by operating the brake;

- by operating the clutch;

- the recall button returns to the stored speed.

The cruise control is not disabled when the accelerator is pressed (e.g. to overtake) and automatically restores the vehicle to the set speed as soon as the accelerator is released.

The ASR function (antispin) takes precedence over cruise control for safety reasons.