GF07.61-P-2003M ME-SFI Starting, Function

GF07.61-P-2003M ME-SFI Starting, Function

Component Identification:

Start quantity control
Additional fuel must be injected during start operation, in line with the coolant temperature, in order to facilitate starting of a cold engine. The increased fuel injection quantity is achieved by extending the injection time.

Battery voltage and voltage supply
The injected fuel quantity is determined by the opening times of the fuel injectors. This opening time is dependent on the battery voltage. The ME-SFI control unit extends the injection time in order to compensate the quantity injected if, for example, the battery voltage is low. No further engine start is possible below approx. 7 V.

Post-start enrichment
After the engine is started from cold, enrichment with additional fuel is necessary for a short time. Enrichment compensates for the fuel that precipitates on the cylinder walls and the engine runs smoothly.

Synchronizing fuel injection and firing order
In order to achieve correct synchronization of the fuel injection and firing order for the respective cylinder, the order is synchronized during the first revolutions of the engine. The ME-SFI control unit requires the signals of the camshaft Hall sensor and crankshaft position sensor for this purpose.

Ignition at engine start
When the engine is started up to approx. 500 rpm, the ignition timing point is controlled based on the signals supplied by the camshaft Hall sensor. Only once the engine speed has reached approx. 600 rpm is a transition made from the fixed ignition timing point to the ignition timing point calculated in line with the momentary operating state.

Starter control
The solenoid switch of the starter (circuit 50) is actuated via the starter relay by the engine control unit.

Parking shift lock
Starting is only possible in the selector lever position P/N and when the service brake is operated. The P/N selector lever position information is sent via the CAN from the transmission control unit. The information "service brake operated " arrives via CAN from the ESP control unit (N47-5).

The drive authorization system inhibits the engine management system. Although the starter rotates, the engine does not start.