GF07.61-P-4027MOS Overheating/Pinging Protection, Function

GF07.61-P-4027MOS Overheating/Pinging Protection, Function
- as of model year 09


Function requirements for overheating/knock protection, general points
^ Circuit 87M ON (engine control ON)
^ Engine running

Overheating/knock protection, general points
In case of thermal overload, the overheating/knock protection protects against engine damage and overheating damage to the firewall catalytic converter.

The ME-SFI control unit (N3/10) controls the overheating/knock protection according to information from the following sensors:
- Coolant temperature sensor (B11/4)
- Charge air temperature sensor (B17/8) and pressure sensor downstream of throttle valve actuator (B28/7), engine load
- Crankshaft position sensor (L5), motor speed
- Throttle valve actuator (M16/6), throttle valve position

The ME-SFI control unit limits engine power in order to reduce the heat generated in the cooling system by combustion.

Overheating/knock protection function sequence
If the coolant or charge air temperature is too high, the ME-SFI control unit shifts the ignition timing of the ECI ignition modules for the RH and LH cylinder banks (N92/1, N92/2) towards "retard", depending on engine speed and load, and the throttle valve is no longer fully open.

The ignition timing adjustment is map-controlled by the ME-SFI control unit and starts at a coolant temperature of about 90 °C.

The ignition angle corrections are added by the overheating/knock protection and knock control according to the performance map.