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

ENGINE 275.950 in MODEL 215, 220

ENGINE 275.951 in MODEL 230 up to Model Year 8

ENGINE 275.953 in MODEL 216, 221 up to Model Year 8

ENGINE 275.954 in MODEL 230 up to Model Year 8

ENGINE 275.980 in MODEL 215, 220

ENGINE 275.981 in MODEL 230 up to Model Year 8

ENGINE 275.982 in MODEL 216, 221 up to Model Year 8

ENGINE 285.950 in MODEL 240

ENGINE 285.980 in MODEL 240

Fig 1: Identifying Overheating/Pinging Protection Function Diagram

Courtesy of MERCEDES-BENZ USA

The task of the overheating/pinging protection is to prevent engine damage as a result of excessive thermal overload and overheating damage of the catalytic converters.

At high engine load and coolant temperature, the ignition timing point is retarded corresponding to the rotational speed and load and the throttle valve is no longer opened completely.

The ignition timing point adjustment begins at approx. 90 °C coolant temperature. The timing correction towards "late" is performed by the ME-SFI control unit (N3/10) in accordance with the performance map

The following information is processed in the ME-SFI control unit for this purpose:

Engine speed
Boost air temperature
Coolant temperature
Signal from pressure sensor downstream of throttle valve actuator (load detection)
Signal from pressure sensor upstream of throttle valve actuator (boost pressure)

The ignition angle corrections of the overheating/pinging protection functions and anti-knock control are added based on the performance map.

ME-SFI control unit, location/task/design/ function	GF07.61-P-5000M
Coolant temperature sensor, location/task/ design/function	GF07.04-P-5026M
Crankshaft position sensor, location/task/ design/function	GF07.04-P-4116M
Pressure sensor upstream of throttle valve actuator, location/task/function	GF07.04-P-5048M
Pressure sensor downstream of throttle valve actuator, location/task/function	GF07.04-P-5049M
Charge air temperature sensor, location/task/ function	GF07.04-P-5038M
Throttle valve actuator, location/task/design/ function	GF30.22-P-4101M
ECI ignition system, function	GF15.15-P-3000M
Boost pressure control, function	GF09.40-P-3000M