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

ENGINE 272.945 in MODEL 251.054/154 as of Model Year 2009/AEJ 08 

ENGINE 272.967 in MODEL 164.186 as of Model Year 2009/AEJ 08 MOPF 

ENGINE 272.967 in MODEL 251.056/065/156/165 as of Model Year 2009/AEJ 08 

ENGINE 273.923 in MODEL 164.871 as of Model Year 2009/AEJ 08 

ENGINE 273.963 in MODEL 164.172 as of Model Year 2009/AEJ 08 MOPF 

ENGINE 273.963 in MODEL 164.886, 251.072/172 as of Model Year 2009/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:

• Hot film MAF sensor (B2/5), engine load
• Intake air temperature sensor (B2/5b1)
• Coolant temperature sensor (B11/4)
• Crankshaft Hall sensor (B70), motor speed

Overheating/knock protection function sequence 

If the coolant or intake air temperature is too high, the ME-SFI control unit no longer fully opens the throttle valve actuator (M16/6), depending on engine speed and load. The ME-SFI control unit shortens the injection time at the fuel injection valves (Y62) according to the lower air mass.

The ME-SFI control unit also actuates the heating element in the three-disk thermostat valve (Y110), so that the three-disk thermostat is fully open and all the coolant is cooled by the engine radiator.

	Electrical function schematic for overheating/pinging protection, function ME	Model 164		PE07.61-P-2777-97MAA
		Model 251		PE07.61-P-2777-97RAA
	ME-SFI [ME] control unit, component description	N3/10	Engine 272	GF07.61-P-6000MIG
		N3/10	Engine 273	GF07.61-P-6000MLG