ME-SFI maximum engine speed limitation, function - GF07.61-P-3007AMG

ENGINE 156.980 in MODEL 164, 251 up to Model Year 8 

ENGINE 156.982 in MODEL 209 

ENGINE 156.983 in MODEL 211, 219 

ENGINE 156.984 in MODEL 216, 221 up to Model Year 8 

Fig 1: Identifying ME-SFI CAN Communication Diagram (Maximum Engine Speed Limitation)

Courtesy of MERCEDES-BENZ USA

The ME-SFI [ME] control unit detects the engine speed via the crankshaft Hall sensor signal. The engine speed is limited to protect the engine and the drive train through:

• Reduction of the opening angle of the throttle valve actuator
• Adjustment of the ignition angle to "retarded"
• Cutting-out fuel injection valves

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

   In order to protect the torque converter in selector lever positions P or N (no power flow) from excessive static internal pressure, the maximum engine speed is limited to approx. 4200 rpm.

2. Driving mode 

   In order to protect the engine from the consequences of impermissibly high engine speeds, the maximum engine speed is limited in 2nd to 7th gear for about 10 seconds to about 7200 rpm and thereafter to 7000 rpm.

   In 1st gear the maximum engine speed is limited to about 6700 rpm.

   The driving mode is detected from the speed signal by the ESP control unit.

3. Throttle valve actuator defective 

In the case of a defective throttle valve actuator, the maximum engine speed is limited through cutting out the fuel injection valves at about 1400 rpm.