ME-SFI control unit function - GF07.61-P-5000-02H
Control of fuel injection system
The fuel injectors are actuated individually, in line with the firing order (sequentially), on the basis of the input signals and the maps stored in the ME-SFI control unit. The ME-SFI control unit calculates the opening times (injection times) of the fuel injectors.
Control of ignition system
The ME control unit actuates the ignition coils in line with the input signals and the maps stored in the ME control unit. The ME-SFI control unit calculates the ignition angle values and controls the anti-knock control (AKC).
Control of idle speed control
The ME control unit actuates the throttle valve actuator in line with the input signals and the performance maps stored in the ME control unit.
Control of cruise control
The ME control unit actuates the throttle valve actuator for the cruise control function on the basis of the input signals and the position of the cruise control push-button switch.
Additional cruise control functions are the variable vehicle speed limiter (except
), the individually programmable permanent maximum speed and Distronic.
Drive authorization system/immobilizer
The ME-SFI control unit is always equipped with an immobilizer. When the vehicle is locked, the DAS transmits information to the ME control unit, which thereupon interlocks the engine control.
The engine can be started (start enable) only once the vehicle is again opened with the authorized key and the DAS transmits a corresponding message to the ME control unit.
Engine speed signal
The ME-SFI control unit generates the short-circuit proof engine speed signal TNA from the signals supplied by the crankshaft position sensor, and outputs it to other control units as follows:
- Square-wave signal with constant on/off ratio
- Maximum current approx. 20 mA
- 3 Pulses/crankshaft revolution
Fuel consumption signal
The fuel consumption signal is computed from the injection times (e.g. 8 liters/hr) and the current fuel consumption is advised to a trip computer by means of square-wave pulse packages.
One square-wave pulse means 0.2 l/h.
Version coding
is used for adapting the ME control unit to different vehicle versions and vehicle equipment by means of matching code numbers. The coding should be performed with STAR DIAGNOSIS. The following vehicle versions or equipment versions can be coded using the variant coding:
- Vehicle model
- National version
- with or without TWC
Delayed-off running
After switching off the ignition, the ME control unit carries out a computer delayed-off running, in which certain data memory (e. g. diagnostic trouble code memory) is updated. The duration is dependent on the coolant temperature (at 80 °C approx. 4 s, at 20° C approx. 60 s and at -30° C approx. 150 s). If the ignition is switched off without starting the engine, the delayed-off running time is approx. 4 s.
Diagnosis/DTC memory
The ME control unit checks its input and output signals for plausibility and recognizes possible faults. The following faults can be distinguished:
- Faults which are permanently present.
- Loose contact faults which occur while driving.
The faults are not erased in the ME control unit after circuit 30 is interrupted.
They can be read out and deleted in the ME control unit with STAR DIAGNOSIS.
Functions can be actuated specifically for diagnostic purposes. These are listed in a menu point.
Various engine operating information is transmitted via the CAN databus by the ME control unit to other control units which are connected to the CAN databus.