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

ENGINE 156.984 in MODEL 216.377, 221.077 /177 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:

• LH and RH hot film MAF sensor (B2/6, B2/7), engine load
• Coolant temperature sensor (B11/4)
• Intake air temperature sensor (B17)
• Crankshaft Hall sensor (B70), motor speed

Overheating/knock protection function sequence 

If coolant or intake air temperature is too high, the ME-SFI control unit no longer fully opens the front and rear throttle valve actuators (M16/3, M16/4), 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 two-disk thermostat heating element (R48), so that the two-disk thermostat is fully opened and all the coolant is cooled by the engine radiator.

	Electrical function schematic for overheating/ knocking protection, function ME	Model 216	PE07.61-P-2777-97CAC
		Model 221	PE07.61-P-2777-97SAC
	ME-SFI [ME] control unit, component description	N3/10	GF07.61-P-6000MAS