GF07.61-P-5000-02M

ME-SFI control unit, function

Control of fuel injection system The ME-SFI control unit actuates the fuel injection valves separately according to the firing order (sequentially) and the input signals and performance maps stored in the ME-SFI control unit. The ME-SFI control unit calculates the opening times (injection times) of the fuel injection valves. Control of ignition system The ME-SFI control unit actuates the ECI ignition system according to the input signals and the performance maps stored in the ME-SFI control unit. The ME-SFI control unit calculates the ignition angle values and controls anti-knock control (AKC). Control of idle speed control The throttle valve actuator is actuated on the basis of the input signals and performance maps stored in the ME-SFI control unit.

Control of cruise control The ME-SFI control unit operates the throttle valve actuator for the cruise control function on the basis of the input signals and the position of the cruise control switch. Additional cruise control functions are the variable speed limiter and Distronic. Diagnosis/DTC memory The ME-SFI control unit checks its inputs and outputs for plausibility and recognizes possible faults. The following faults can be distinguished: - Faults constantly present. - Loose contact faults which have occurred during a journey. The faults are erased in the ME-SFI control unit after circuit 30 is interrupted.

Drive authorization system/immobilizer The ME-SFI control unit is always equipped with an immobilizer. When the vehicle is locked, the drive authorization system control unit transmits information over the CAN data bus to the ME-SFI control unit, which thereupon interlocks the engine management system (fuel injection system). The engine can be started (start enable) only once the vehicle is again unlocked with the authorized key and the drive authorization system control unit transmits a message to this effect over the CAN data bus to the ME-SFI 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 them to other control units. 3 pulses are output per engine revolution. Actuations with STAR DIAGNOSIS Functions can be actuated specifically for diagnostic purposes. These are listed in a menu item.

Variant coding For adapting the ME-SFI control unit to different vehicle versions and vehicle equipment by means of the respective code numbers. Coding is performed with STAR DIAGNOSIS. The variant coding can be used to code the following vehicle versions and equipment variants: Vehicle model National version With or without TWC Fuel consumption signal The consumption signal is calculated from the injection times (e.g. 8 liters/hour) and is transmitted via CAN to the trip computer in the instrument cluster.

Start recognition The engine control unit is informed of the initiated starting procedure via the CAN message "circuit 50". This is necessary in order, for example, to trigger start quantity control, starter control, post-start enrichment and ignition timing when starting. Model 221 The ME-SFI control unit is the gateway for the drive train CAN and chassis CAN.

Computer run-on After the ignition is switched off, the ME-SFI control unit delays the computer shutdown for a predefined run-on time during which certain data memories are updated (e.g. the DTC memory). 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) and whether the engine was started immediately again. If the ignition is switched off without starting the engine, the run-on time is always approx. 4 s.