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

GF07.61-P-4027MLK Overheating/Pinging Protection, Function
- refinement package
- 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 converters.

The ME-SFI control unit (N3/10) controls the overheating/knock protection according to information from the following sensors:
- Hot film MAF sensor (B2/5), engine load
- Intake air temperature sensor (B2/5b1)
- Coolant temperature sensor (B11/4)
- Crankshaft position sensor (L5), motor speed

Overheating/knock protection function sequence
If the coolant/intake air temperature is too high, the ME-SFI control unit shifts the firing point of the ignition coils (T1) towards "retard", depending on engine speed and load. The ignition angle correction is map-controlled by the ME-SFI control unit.

Firing point adjustment starts when the coolant temperature is about 90 °C and intake air temperature is about 20 °C.

Examples of ignition angle correction towards "retard":
- with coolant at 100 °C, intake air at 20 °C and full load, 2° crank angle
- with coolant at 100 °C, intake air at 60 °C and full load, 8° crank angle
- with coolant at 125 °C, intake air at 60 °C and full load, 11° crank angle

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