A separate output stage-controlled ignition coil which transfers the high tension (up to 32 kV) via the spark plug connectors is provided for each cylinder. In this way changes to the ignition timing can be controlled rapidly and independently.
The effective range for ignition timing control is increased due to the fact that there are no rotating parts.The camshaft sensor is used to ensure the correct firing order is maintained.
On the basis of the engine speed and load signals, the DME control unit determines the ignition angle (ignition timing) which is output via the ignition output stages. This function also takes other input signals into consideration such as the engine temperature, intake air temperature, throttle position, knock control signals and adaptive transmission control signals.
In the event of failure of the cylinder reference sensor (camshaft sensor), the system switches over to parallel ignition, i.e. the ignition coils of the individual cylinders are controlled with fixed ignition timing values during each crankshaft revolution.