GF07.61-P-3007MOS ME-SFI Maximum Engine Speed Limitation, Function

GF07.61-P-3007MOS ME-SFI Maximum Engine Speed Limitation, Function
- as of model year 09


Function requirements maximum engine speed limitation, general points
^ Circuit 87M ON (engine control ON)
^ Engine running

Maximum engine speed limitation, general points
The maximum engine speed is limited to protect the engine and the drivetrain. The ME control unit (L5) detects the engine speed via the crankshaft position sensor signal (N3/10). The ME-SFI control unit adjusts the maximum engine speed according to the following sensors and signals:
- Crankshaft position sensor, engine speed
- Throttle valve actuator (M16/6), throttle valve position
- ETC control unit (N15/3), selector lever position over the drive train CAN (CAN C)
- ESP control unit (N47-5), vehicle speed over the chassis CAN (CAN E)

The ME-SFI control unit limits the maximum engine speed through the following measures:
- Reduces the opening angle of the throttle valve
- Switching off the fuel injection valves (Y62)

Maximum engine speed limitation, function sequence
The ME-SFI control unit controls the maximum engine speed in the following conditions:
^ Torque converter protection function sequence
^ Driving mode function sequence
^ Throttle valve actuator fault function sequence
^ Missing variant coding function sequence

Torque converter protection function sequence
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. The ME-SFI control unit receives information about the current selector lever position from the ETC control unit over the drive train CAN.

Driving mode function sequence
In driving mode, in order to protect the engine from inadmissibly high engine speeds, the maximum engine speed is first limited to about 6200 rpm and then, after 10 s, to about 6000 rpm.
The ME-SFI control unit detects the driving mode on the "vehicle speed" CAN signal from the ESP control unit (over the chassis CAN).

Throttle valve actuator fault function sequence
In the event of a defective throttle valve actuator, the maximum engine speed is limited in idle to approx. 1400 rpm and in driving mode to approx. 1800 rpm.

Missing variant coding function sequence
If no variant coding exists, maximum engine speed is limited to 2400 rpm.