On a diesel engine, an ignition system is not required, because due to the high compression ratio, the air is heated to such an extent that, after fuel injection, it spontaneously ignites.
BMW petrol engines are equipped with a parametric ignition system, which is controlled by the Motronic control unit. The Motronic control unit also provides electronic fuel injection control.
The ignition system consists of:
- ignition coils (on the M50 engine, an ignition coil is installed on each cylinder),
- spark plugs,
- high-voltage ignition distributor with slider (missing on the M50 engine),
- position sensors,
- DME control unit (DME = Digital Engine Management System - Motronic).