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INJECTION
OPERATING PHASES : BOSCH ME 7.9.5 INJECTION SYSTEM
Engine : CFA
Regulation of the idling speed
The engine is equipped with an idle regulation stepper motor :
Important variations in the engine idling speed due to the different accessories on the vehicles, depending on their operating status (aircon, alternator)
Variations in engine idling speed due to the ageing of the engine
This device enables a progressive return to idling speed.
Role of the idle regulation function:
- To regulate the idling speed
- To obtain a fast idle speed that decreases with the warming up of the engine
- To improve the idling speed for the vehicle in motion
Engine starting
Entry into starting phase occurs as soon as the injection ECU is powered.
During starting the injection ECU commands the following components:
- Priming pump (low pressure) (cut-off after 3 seconds, provided the starter motor has not operated)
- The electrical supply of the oxygen sensors
Functioning of the transitory engine speeds
Command of the injectors is corrected as a function of the following variations:
- Butterfly position
- Pressure in the inlet manifold
The detection of these engine speeds (accelerations/decelerations) is by intermediary of the butterfly potentiometer or of the pressure sensor.
In these operating modes the quantity of fuel injected depends on the variation of the butterfly angle or on the variation of the pressure
Correction for full load
Approaching full load, the air/fuel mixture has to be made richer in order to obtain optimum engine performance.
In the case of a system with an oxygen sensor loop, the information on this is not taken into account by the ECU.
The ECU then controls the injection in open loop.
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