CDI start quantity control, function - GF07.16-P-3000IC

ENGINE 647.961 in MODEL 211 

ENGINE 648.960 in MODEL 220 

ENGINE 648.961 in MODEL 211 

Fig 1: CDI Start Quantity Control Function Chart

The start quantity control determines the injection quantity (start quantity) for an engine start according to the coolant temperature (irrespective of the accelerator pedal position).

Via the signals from the camshaft Hall sensor and the crankshaft position sensor, the CDI control unit detects the ignition TDC position of cylinder 1. Using this information, the CDI control unit synchronizes injection timing and calculates the start quantity required independently of the coolant temperature. The higher the coolant temperature, the lower the start quantity.

The fuel pressure built up during the start procedure via the high-pressure pump is controlled by the CDI control unit via the pressure regulator valve and measured by the rail pressure sensor.

The start quantity is controlled independently of the accelerator pedal position up to the engine start speed (e.g. 500 rpm at a coolant temperature of 80°C) by the start quantity control.

The engine speed cannot be controlled by the accelerator pedal until the engine start speed is exceeded.