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

GF07.61-P-3007MLK ME-SFI Maximum Engine Speed Limitation, Function
- refinement package
- 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).

To do this, the ME-SFI control unit reads the following sensors and signals:
- Crankshaft position sensor, engine speed
- Throttle valve actuator (M16/6), throttle valve position
- Electric controller unit (VGS) (Y3/8), selector lever position via engine compartment CAN (CAN-C)
- ESP and BAS control unit (N47-5), vehicle speed through the engine compartment

The ME-SFI control unit limits the maximum engine speed through the following measures:
- Reduces the opening angle of the throttle valve actuator
- Shifts the ignition angle of the ignition coils (T1) towards "retard"
- Cutout of fuel injection valves (Y62)

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

Throttle valve actuator fault function sequence
If the throttle valve actuator is defective, maximum engine speed is limited to about 1500 rpm.

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 fully integrated transmission controller unit over the engine compartment CAN.

Driving mode function sequence
When driving, in order to protect the engine from the effects of inadmissibly high engine speeds, maximum engine speed is limited to 6700 rpm for about 3 s, and then 6500 rpm.
When driving, the vehicle speed signal is detected by the ESP control unit over the engine compartment CAN.