General information
The ignition system is controlled by the electronic engine control unit (BEU). The ignition system is integrated with the fuel injection system, and forms a single system with it.
Ignition control is based on information received by the ECU from various sensors (load and speed of the engine, temperature in the cooling system, temperature of the air entering the engine).
Some engines are equipped with a knock sensor. This sensor responds to the vibration that occurs when the working mixture ignites spontaneously. When detonation occurs, the sensor sends a signal to the ECU, which reduces the ignition timing until detonation disappears.
All models have a distributorless ignition system with its own ignition coil for each cylinder. On all engines except the M43TU engine, the coils are located next to the spark plugs. The M43TU engine has a coil pack located on the engine compartment mudguard, from where high-voltage wires are extended to all candles.
Based on the signals from the sensors, the BEU determines the required ignition moment and the period of the coil on state. During idling, the ECU can change the ignition timing for stable engine operation.
Precautionary measures
Follow the precautions at the beginning of chapter 5A.
Checking the ignition system and its elements should be entrusted to a BMW dealer or a specialist workshop with specialized equipment. Checking electrical circuits using universal devices is, firstly, very laborious, and secondly, it poses a danger to semiconductor devices, in particular, to BEU.