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Maximum engine speed limitation, ME-SFI function - GF07.61-P-3007M

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 

Shown on models 215, 220, 230, 240 

Fig 1: Identifying ME-SFI Function Diagram For Maximum Engine Speed Limitation
G07537656Courtesy of MERCEDES-BENZ USA

Function 

The ME-SFI control unit detects the engine speed from the signal supplied by the crankshaft position sensor. Engine speed is limited by shutting off the fuel injectors in the following conditions as a protection for the engine and the drive train:

  1. Torque converter protection in selector lever position P/N 

    In order to protect the torque converter in selector lever positions P and N (no power transmission) from excessive static internal pressure, engine speed is limited to approx. 2500 rpm.

  2. Limiting maximum engine speed when driving 

    In order to protect the engine from the consequences of impermissibly high rotational speeds, engine speed is limited to 6200 rpm and, after a further 10 seconds, to approx. 6000 rpm The drive mode is detected from the vehicle speed signal.

  3. Safety fuel shutoff 

    In case of a defective throttle valve actuator, the actuation of the fuel injection valves is interrupted over approx. 1400 rpm. If the engine speed has dropped to approx. 1200 rpm, the fuel injection valve are actuated again (strong surging engine operation).

ME-SFI control unit, location/task/design/ function   GF07.61-P-5000M 
Crankshaft position sensor, location/task/ design/function   GF07.04-P-4116M 
Safety fuel shutoff, ME-SFI function   GF07.61-P-3018M 
ETC control unit, location/task Selector lever position information P/N and driving position engaged.
Transmission 722.6
GF27.19-P-4012G
Throttle valve actuator Location/task/design/function   GF30.22-P-4101M