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CDI idle speed control, function - GF07.16-P-3002IC

ENGINE 647.961 in MODEL 211 

ENGINE 648.960 in MODEL 220 

ENGINE 648.961 in MODEL 211 

Fig 1: CDI Idle Speed Control Function Chart
G04987354

Idle speed control keeps the idle speed constant, even during load requests, such as drive position selected (with automatic transmission) or when coolant compressor is switched on (A9).

For this purpose, the CDI control unit calculates the target engine speed and performs a target-actual value comparison. Accordingly, the CDI control unit controls the rail pressure via the quantity control valve and the pressure regulator valve and controls injection timing via the fuel injectors.

Rail pressure and injection time determine the quantity of fuel injected.

The following input signals are evaluated by the CDI control unit for idle speed control:

  Component description for the fuel injectors Y76 GF07.03-P-6120IC 
  Component description for the crankshaft position sensor L5 GF07.04-P-6010IC 
  Component description for the coolant temperature sensor B11/4 GF07.04-P-6040IC 
  Component description for the rail pressure sensor B4/6 GF07.04-P-6210IC 
  Component description for the quantity control valve Y94 GF07.05-P-6010IC 
  Component description for the pressure regulator valve Y74 GF07.05-P-6020IC 
  Component description for the CDI control unit N3/9 GF07.16-P-6000IC
  Component description for the accelerator pedal sensor B37 GF30.20-P-2010IC