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

GF07.61-P-3007MIG 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. On the signal from the crankshaft Hall sensor (B70), the ME-SFI control unit (N3/10) detects engine speed. The ME-SFI control unit adjusts the maximum engine speed according to the following sensors and signals:
- Crankshaft Hall 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 control unit (N47-5), vehicle speed over the engine compartment CAN

The ME-SFI control unit limits the maximum engine speed through the following measures:
- Reduces the opening angle of the throttle valve
- 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:
^ 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 the information about the current selector lever position from the electric controller unit (VGS) over the engine compartment CAN.

Driving mode function sequence
In order to protect the engine from inadmissible engine speeds during driving mode, the maximum engine speed is limited 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 engine compartment 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.