#AcidGasInjectionSystemServices

[step-engineering-blog]

HIGH PRESSURE INJECTION

The high pressure direct injection system is intended to deliver to the engine a quantity of diesel fuel at a given time.

 DESCRIPTION

The system consists of:

·        A fuel filter,

·        A high pressure pump integrating the suction pump,

·        A pressure regulator attached to the pump,

·        An injection ramp,

·        A pressure sensor installed on the ramp,

·        4 electromagnetic injectors,

·        Different sensors,

·        An injection computer,

·        A priming pear.

 OPERATION

The common rail high pressure direct injection system is a sequential type diesel fuel injection system (based on the operation of multipoint injection for gasoline engines).

This new injection system makes it possible, thanks to the pre-injection process, to reduce operating noise, to reduce the amount of particles and pollutant gases and to provide high engine torque at low engine speeds.

The high pressure pump generates the high pressure that it directs towards the injection rail. The high pressure regulator on the pump controls the high pressure value according to the demand determined by the computer. The ramp feeds each injector via a steel pipe.

Acid gas injection system Services

 The calculator:

· Determines the injection pressure value needed for proper engine operation and then controls the pressure regulator. It verifies that the pressure value is correct by analyzing the value transmitted by the pressure sensor located on the ramp,

· Determines the injection time required to deliver the correct amount of diesel and when to start the injection,

· Electrically and individually pilot each injector after having determined these two values.

 The flow injected into the engine is determined according to:

·        The duration of piloting of the injector,

·        The speed of opening and closing the injector,

·        The stroke of the needle (determined by a constant for a type of injector),

·        The nominal hydraulic flow of the injector (determined by the type of injector),

·        The high pressure ramp pressure regulated by the computer.

 IMPORTANT

The engine must not run on diesel fuel containing more than 10% diester.

It should not work either with a tiny percentage of gasoline.

 The system can inject diesel into the engine up to a pressure of 1600 bar. Before each intervention, check that the fuel rail is no longer under pressure and that the fuel temperature is not too high.

During each intervention on the high-pressure injection system, the instructions for cleanliness and safety stated in this document must be observed.

When repairing or removing the high-pressure pump, injectors, supply, return and high-pressure outlet connections, the openings must be fitted with new shutters suitable for avoiding impurities.

It is forbidden to disassemble the inside of the pump and the injectors. (Only the pressure regulator, the diesel temperature sensor and the venturi can be changed on the pump).

It is forbidden to loosen a high pressure hose connection while the engine is running.

It is not possible for pollution problems to separate the pressure sensor from the fuel rail. In the event of a pressure sensor failure, the pressure sensor and manifold assembly must be changed, plus the 5 high pressure hoses.

 The pulley of the injection pump is not separable from the pump (cracks appear on the pulley during extraction). If the pump is changed, the pulley must also be changed.

It is forbidden to repair the wiring connected to the accelerometer (knock sensor) and to the engine speed sensor. In case of failure, replace it with new wiring.

It is forbidden to feed 12v directly any component of the system.

Decalcification and ultrasonic cleaning are prohibited.

Never start the engine unless the battery is reconnected properly.

Disconnect the injection computer during welds on the vehicle.

On the injectors, there is a 16-character code. This code characterizes the flow of the injectors. This code is specific to each injector. If the injector is changed, the code of the new injector must be memorized in the computer.

 In case of change of the computer, it is necessary to inform in the calculator, the code of the 4 injectors.

 From there, two possibilities:

If it is possible to communicate with the calculator:

· Download the calculator data into the diagnostic tool

· Change the calculator

· Transfer the data from the diagnostic tool to the calculator

· With the aid of the diagnostic tool, make sure that the computer has not detected any fault related to the injection codes and that the warning light on the instrument panel is off.

 If it is impossible to communicate with the calculator:

· Change the calculator

· Read the data on injectors

· Store them in the calculator using the diagnostic tool

· Make sure, using the diagnostic tool, that the computer has not detected a fault related to the fuel injection codes and that the warning light on the instrument panel is off.

All disassembled high pressure hoses must be changed as well as staples.