On all models except L3.1 and LU2, the ignition system is integrated with the fuel injection system and is controlled from a single ECU.
Bosch Motronic ML4 systems. l and Fenix IB have a distributor cap and rotor to distribute the ignition spark to the cylinders (together with a conventional ignition coil).
All other models use an ignition system consisting of only two ignition coils. The ignition coil actually consists of two separate windings that supply a spark to two cylinders each (one for cylinders 1 and 4 and one for cylinders 2 and 3). The ignition pulse is applied to two spark plugs at once for each engine cycle, one on the compression stroke and one on the exhaust stroke - the ignition spark on the exhaust stroke has no effect on the operation of the engine, so it is wasted. The ECU uses inputs from various sensors to calculate the required ignition timing and ignition coil storage time.
On some models, the knock sensor is included in the ignition system. The sensor is mounted on the cylinder head and prevents detonation in the cylinders under load. The sensor is sensitive to vibration and detects detonation, which occurs when the fuel mixture in the cylinders burns with detonation. The knock sensor sends an electrical signal to the ECU, which in turn decreases the ignition timing until knock stops.