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

GF07.61-P-3007MIS 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 [ME] control unit (N3/10) detects engine speed. The ME-SFI [ME] 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 over the drive train CAN (CAN C)
- ESP control unit (N47-5) or regenerative braking system control unit (N30/6) (for Hybrid), vehicle speed via the chassis CAN (CAN E)

The ME-SFI [ME] control unit limits the maximum engine speed by means of the following measures:
- Reduces the opening angle of the throttle valve
- Shifting the ignition angles of the ignition coils (T1) to "retard"
- Switching off the fuel injection valves (Y62)

Function sequence for maximum engine speed limitation
The ME-SFI [ME] control unit controls the maximum engine speed in the following conditions:
^ Function sequence for torque converter protection
^ Function sequence for driving mode
^ Function sequence for throttle valve actuator fault
^ Function sequence for missing variant coding

Function sequence for torque converter protection
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 [ME] control unit receives the information about the current selector lever position from the electric controller unit (VGS) via the drivetrain CAN.

Function sequence for driving mode
In order to protect the engine from inadmissible engine speeds during driving mode, the maximum engine speed is limited to about 6000 rpm.
Driving mode is recognized by the ME-SFI [ME] control unit on the CAN signal "vehicle speed" by the ESP control unit or regenerative braking system control unit (for Hybrid) via the chassis CAN.

Function sequence for throttle valve actuator fault
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.

Function sequence for missing variant coding
If no variant coding exists, maximum engine speed is limited to 2400 rpm.