Fuel Injection Control; Main Injection Timing Control; Pilot Injection Timing Control - SSANGYONG 2004 Rexton 2.7XDi Workshop Manual

FUEL INJECSTION CONTROL

Fuel Injection Control

Injection control is used in order to determine the characteristics of the pulse which is sent to the injectors.
Injection control consists as below.
• Injection timing
• Injection volume
• Translating fuel injection timing and injection volume into values which can be interpreted by the injector driver.
- a reference tooth (CTP)
- the delay between this tooth and the start of the pulse (Toff)
- the pulse time (Ton)

Main injection timing control

The pulse necessary for the main injection is determined as a function of the engine speed and of the injected flow.
The elements are;
• A first correction is made according to the air and coolant temperatures.
This correction makes it possible to adapt the timing to the operating temperature of the engine. When the engine is
warm, the timing can be retarded to reduce the combustion temperature and polluting emissions (NOx). When the
engine is cold, the timing advance must be sufficient to allow the combustion to begin correctly.
• A second correction is made according to the atmospheric pressure.
This correction is used to adapt the timing advance as a function of the atmospheric pressure and therefore the altitude.
• A third correction is made according to the coolant temperature and the time which has passed since starting.
This correction allows the injection timing advance to be increased while the engine is warming up (initial 30 seconds).
The purpose of this correction is to reduce the misfiring and instabilities which are liable to occur after a cold start.
• A fourth correction is made according to the pressure error.
This correction is used to reduce the injection timing advance when the pressure in the rail is higher than the
pressure demand.
• A fifth correction is made according to the rate of EGR.
This correction is used to correct the injection timing advance as a function of the rate of exhaust gas recirculation.
When the EGR rate increases, the injection timing advance must in fact be increased in order to compensate for the
fall in termperature in the cylinder.
During starting, the injection timing must be retarded in order to position the start of combustion close to the TDC. To do
this, special mapping is used to determine the injection timing advance as a function of the engine speed and of the
water temperature. This requirement only concerns the starting phase, since once the engine has started the system
must re-use the mapping and the corrections described previously.

Pilot injection timing control

The pilot injection timing is determined as a function of the engine speed and of the total flow.
The elements are;
• A first correction is made according to the air and coolant temperatures.
This correction allows the pilot injection timing to be adapted to the operating temperature of the engine.
• A second correction is made according to the atmospheric pressure.
This correction is used to adapt the pilot injection timing as a function of the atmospheric pressure and therefore the
altitude.
During the starting phase, the pilot injection timing is determined as a function of the engine speed and of the coolant
temperature.
ENGINE CONTROL SYSTEM
DI ENG SM - 2004.4
DI08-13
CHANGED BY
EFFECTIVE DATE
AFFECTED VIN