ECM starting function

L07.53-0004-06

17 Fuel rail

55/1 Fuel filter with integrated fuel pressure regulator

80 Fuel tank

K1/6 Gasoline engine management relay

K27 Fuel pump relay module

M3/3 Fuel pump with fuel level sensor

N3/18 Engine control module with integrated throttle valve actuator

N3/18m1 Throttle valve actuator

S2 Starter switch

Y62 Injectors (LH-SFI, HFM-SFI, PEC [LH, HFM, PMS])

X11/4 Diagnostic data link connector

CAN Databus (Controller Area Network)

Functions when ignition ON (ignition/start switch circuit 15):

 Supplying ECM fuel injection and ignition system with voltage.

 Actuating fuel pump for about 1 s (audible).

An engine start must be completed, however, before repeated actuation of the fuel pump.

 Indicator lamps in the instrument cluster must light up (bulb check).

 At ignition ON, data are exchanged over the CAN databus (e.g. for drive authorization).

Start recognition

Once the engine start operation is initiated, the start switch supplies a signal to the engine control module. This signal is required, for example, for the start quantity control, the start control, the post-start enrichment and for the ignition system.

Start quantity control

In order to facilitate starting of the engine when cold, additional fuel must be injected during engine start operation, depending on the coolant temperature. The injected quantity is increased by extending the injection time.

The start quantity control is dependent on:

 Start recognition

 Coolant temperature

 Engine speed

 Engine off time (during processor delayed off 30 sec.)

 Atmospheric pressure

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The start quantity control is activated after start recognition. It continues to remain activated until a temperature-related engine speed is exceeded.

The higher the coolant temperature, the smaller is the start quantity enabled by the engine control module.

Starter control

When the ignition/start switch is turned from position 2 into the start position, the start recognition is supplied by the engine control module through circuit 50. Once engine start speed reaches 400 to 700 rpm, the engine control module interrupts the ground actuation to the starter relay and thus the engine start operation.

Post-start enrichment

After starting the engine from cold, it is necessary to enrich the mixture with additional fuel for a short time. The fuel which precipitates on the cylinder walls, is compensated for by this enrichment and the engine runs smoothly.

Post-start enrichment is dependent on:

 Coolant temperature at engine start

 Time period after start

 Selector lever position

 Correction programming with STAR DIAGNOSIS

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Battery voltage and voltage supply

The quantity of fuel injected is determined by the opening times of the fuel injectors. This opening time is dependent on the battery voltage. In order to compensate for the quantity of fuel injected, for example if the battery voltage is low, the engine control module with integrated throttle valve actuator extends the injection time. If the operating voltage at engine start is < 5.5 V, no engine start is possible.

Synchronizing fuel injection and firing order

In order to achieve correct assignment of the fuel injection and firing order to the relevant cylinder, the order is synchronized during the first revolutions of the engine. The engine control module with integrated throttle valve actuator 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 about 200 rpm, the ignition timing point is controlled only on the basis of the signals supplied by the crankshaft position sensor. Only once the engine speed has reached approx. 300 rpm is a transition made from the fixed ignition timing point to the ignition timing point calculated in line with the momentary operating state.

Warming-up control

The warming-up control is designed to further enrich the fuel-air mixture after start and post-start enrichment because part of the fuel-air mixture precipitates on cold parts of the engine.

The additional quantity of fuel is metered to the engine in line with the map. The injection time is extended accordingly for this purpose.

The warming-up enrichment is dependent on:

 Coolant temperature at engine start

 Intake air temperature

 Engine speed

 Engine load

 Idle speed/part load operation

 Correction programming with STAR DIAGNOSIS

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The drive authorization system control module intervenes in the engine control module for implementing drive authorization. The system inhibits the engine control module if an unauthorized intention to use exists.