Starting ignition timing

/ 9-3 (9400) / 2001 / 2. Engine / Trionic T7 / Technical description / Starting ignition timing

Starting ignition timing is active from the point when the engine starts until the engine speed has reached the requested idling speed.

Ignition timing is normally 10° BTDC but is retarded when the intake air temperature exceeds 4°C. When the intake air temperature reaches 100°C, the ignition advance will be 3° BTDC. The reason for the ignition being retarded when the air temperature increases is that the combustion velocity then also increases.

During start, the control module triggers each cylinder with 200 Hz for 60 crankshaft degrees, which generates a multispark. As the engine speed reaches above 450 rpm, the frequency will increase to 330 Hz. The function is terminated when the engine speed exceeds 650 rpm. If the engine speed drops below 450 rpm again, the function will be reactivated provided the engine coolant temperature is below -10°C.

This is to ensure ignition in unfavourable starting conditions and to prevent the engine from stalling directly after start.

Starting ignition timing

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