Starting ignition timing

/ 9-3 (9400) / 1999 / 2. Engine / Trionic T7, 4-cyl / 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.

When starting, the control module will trigger each cylinder with 200 Hz during 60 crankshaft degrees to provide a so-called multispark. The frequency is increased to 330 Hz once the engine speed exceeds 450 rpm. This function ceases when the engine speed exceeds 650 rpm. The function will restart if the engine speed drops below 450 rpm again.

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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