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

GF07.61-P-2003MS ME-SFI Starting, Function
- up to model year 08

Component Identification:

The ME-SFI [ME] control unit is the gateway for the drive train CAN and chassis CAN.

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 control unit extends the injection time to compensate the quantity injected if 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. The fuel which precipitates on the cylinder walls, is compensated for by this enrichment, and the engine runs smoothly.

Synchronizing of 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 from the camshaft Hall sensor and crankshaft position sensor for this purpose.

Ignition at engine start
When the engine is started and up to approx. 500 rpm, ignition timing is controlled only on the basis of the signal 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 starter solenoid switch is actuated via circuit 50, relay starter by the engine control unit. The voltage supply to the relay is supplied via circuit 15, relay starter. This voltage supply is fused at the front prefuse box (fuse 9).

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.