Overheating/pinging protection, function - GF07.61-P-4027MOS

ENGINE 275.953 in MODEL 216.376, 221.176 as of Model Year 09 /AEJ 08 

ENGINE 275.982 in MODEL 216.379, 221.179 as of Model Year 09 /AEJ 08 

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.

	Electrical function schematic for overheating/ pinking protection, function ME	Model 216	PE07.61-P-2777-97CAA
		Model 221	PE07.61-P-2777-97SAA
	ME-SFI [ME] control unit, component description	N3/10	GF07.61-P-6000MOS