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

ENGINE 273 in MODEL 463.202/222/236/237 up to 31.5.12 as of model year 2009/YoM 08

Fig 1: Identifying ME-SFI Maximum Engine Speed Limitation, Function Chart

Courtesy of MERCEDES-BENZ USA

Function requirements for maximum engine speed limitation for the ME gasoline injection and ignition system (motor electronics) (ME), general points

Circuit 87M ON (engine control ON)
Engine running

ME maximum engine speed limitation, general points

The maximum engine speed is limited to protect the engine and the drivetrain. The ME-SFI [ME] control unit detects the engine speed via the crankshaft Hall sensor signal. 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, throttle valve position
Electric controller unit (VGS), selector lever position via the drive train CAN
ESP control unit, vehicle speed via the drive train CAN

The ME-SFI [ME] 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 towards "retard"
Shuts off the fuel injection valves (Y62)

Maximum engine speed limitation, function sequence

The ME-SFI [ME] 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.

n = 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 drive train 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 n = 6000 rpm.

The ME-SFI [ME] control unit detects the driving mode on the "vehicle speed" signal from the ESP control unit via the drive train 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. n = 1400 rpm and in driving mode to approx. n = 1800 rpm.

Missing variant coding function sequence

If no variant coding exists, maximum engine speed is limited to n = 2400 rpm.

Component description for ME-SFI [ME] control unit	N3/10	GF07.61-P-6000G
Component description for ESP control unit	N30/4	GF42.45-P-5118G
Component description for fully integrated transmission control unit	Y3/8n4	GF27.60-P-5165GGA