The ignition timing is controlled by an electronic control system. The values of the optimal ignition timing for all engine operating modes are recorded in the memory of the electronic engine control unit (ECM).
Engine operating mode (engine speed, load, engine thermal condition, etc.) determined by the signals of various sensors. Based on the signals from the sensors and data on the optimal ignition timing, the electronic engine control unit (ECM) sends signals to interrupt the current in the primary winding of the ignition coil.
A high voltage is generated in the ignition coil for sparking, and thus the ignition timing is controlled.