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Home >> Mercedes Benz >> 2007 >> ML63 >> Repair and Diagnosis >> Engine Performance >> Ignition System >> Fuel, Ignition, Engine Control - Basic Knowledge - 1 Of 2 -- 164 Chassis >> Basic Knowledge >> CDI limiting maximum engine speed, function - GF07.16-P-3007P
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CDI limiting maximum engine speed, function - GF07.16-P-3007P

ENGINE 642 in MODEL 164.1 /8, 203.0 /2, 209.3 /4, 211.0 /2 /6, 219.3, 221.0 /1, 251.0 /1 

ENGINE 642 in MODEL 463.3 

ENGINE 642 in MODEL 461.3 

The maximum engine speed limitation is used to restrict the engine speed to approx. 4500 RPM. This counteracts mechanical damage to the engine caused by over-revving. To do this the CDI control unit (N3/9) reads in the crankshaft Hall sensor (B70) and uses its signal to determine the motor speed. Above an engine speed of around 4500 RPM, the CDI control unit interrupts actuation of the fuel injectors (Y76) and reduces the fuel pressure in the rail via the quantity control valve (Y94) and the pressure control valve (Y74).

If the engine speed falls back down to under around 4500 RPM, then the CDI control unit re-actuates the fuel injectors and increases the fuel pressure in the rail via the quantity control valve and the pressure control valve.

  Component description for fuel injectors Y76 GF07.03-P-6120P 
  Component description for the crankshaft Hall sensor B70 GF07.04-P-6220P 
  Component description for the rail pressure sensor B4/6 GF07.04-P-6210P 
  Component description for the quantity control valve Y94 GF07.05-P-6010P 
  Component description for the pressure regulator valve Y74 GF07.05-P-6020P 
  Component description for the CDI control unit Model 203, 209
N3/9
GF07.16-P-6000P
    Model 211, 219
N3/9
GF07.16-P-6000T
    Model 164, 463
N3/9
GF07.16-P-6000GZ
    Model 221
N3/9
GF07.16-P-6000SX
    Model 251
N3/9
GF07.16-P-6000RT
    Model 461
N3/9
GF07.16-P-6000GX
  Component description for the accelerator pedal sensor Model 203, 209, 211, 219
B37
GF30.20-P-2010P
    Model 164, 463
B37
GF30.20-P-2010GZ
    Model 221
B37
GF30.20-P-2010SX
    Model 251
B37
GF30.20-P-2010RT