939003470 - INTRODUCTION - DIESEL FUEL INJECTION SYSTEM

SPECIFICATIONS

FUNCTION

The 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 Alfa CODE control unit (Immobilizer).

1. Auxiliary fuel pump2. Fuel filter3. Fuel return manifold4. Pressure pump5. Pressure regulator on pump6. Supercharging sensor7. Pressure regulator on rail8. Pressure sensor9. Rail10. Throttle body11. E.G.R. solenoid valve12. Oil level sensor13. Timing sensor14. Heater plug15. Turbo vane actuator control solenoid valve16. Flow meter17. Rpm sensor18. Water temperature sensor19. Minimum oil pressure switch20. Lambda sensor downstream of the catalytic converter21. Lambda sensor downstream of the filter (DPF)22. Differential pressure sensor23. Filter (DPF)24. Pedal assembly25. Diagnostic connector26 Injection control unit27. Vehicle wiring28. Engine wiring

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 unit1. Auxiliary electric fuel pump2. Swirl mechanism (where fitted)3. VGT solenoid valve4. Air conditioning compressor5. E.G.R. solenoid valve6. Rev counter7. Cooling fan8. Heater plugs control unit9. Accelerator pedal with built in potentiometer10. Brake - clutch pedal switch11. Differential pressure sensor12. Temperature sensor13. Fuel pressure sensor14. Flow meter15. Coolant temperature sensor16. Fuel temperature sensor17. Cruise control18. Excess pressure and air temperature sensor19. Timing sensor20. Speedometer22. Battery23. Alfa CODE24. Diagnostic socket25. Pressure regulators26. Injectors27. Heater plugs28. Throttle solenoid valve29. Heater plugs warning light30. Injection warning light31. Coolant overheating warning light32. Water in the fuel warning light33. OIL warning lightSelf-diagnosisThe 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.

RECOVERYFrom 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 controlWhen 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 various 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

The injection unit, during the following stages:

• starting;
• post-starting
• applies a timer to the heater plugs preheating control unit based on 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 checkDuring 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 checkAccording 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 checkOn 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 offIn 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.