ME-SFI starting, function

P07.61-2928-09

B4/7 Fuel level sensor

B6/2 Camshaft Hall sensor,
left cylinder bank (with ME2.7.1)

B6/3 Camshaft Hall sensor, right cylinder bank

B11/4 Coolant temperature sensor

K6 Starter relay (model 240)

K40/4 Passenger-side fuse and relay module (model 230)

K40/4kL Starter relay

K40/5kT Rear fuse and relay module, fuel pump relay

(Model 215, 220, 230)

N15/3 ETC [EGS] control unit (transmission 722.6)

N73 EIS [EZS] control unit

N92/1 ECI ignition module, right cylinder bank

N92/2 ECI ignition module, left cylinder bank

N118 Fuel pump control unit

Y62 Fuel injection valves

CAN Data bus

K40/7 Right front fuse and relay module (model 215, 220)

K40/7kL Starter relay

L5 Crankshaft position sensor

M1 Starter

M3 Fuel pump

M16/6 Throttle valve actuator

N3/10 ME-SFI control unit

N10/8kA Fuel pump relay

(SAM control unit with rear fuse and relay module 2, model 240)

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.

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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.

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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).

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