Ignition Timing Control: Notes

A microcomputer in the ECU controls the ignition timing according to the engine speed and vacuum pressure in the intake manifold. Engine speed and vacuum pressure are transmitted to ECU by signals from Crank sensor, cylinder (CYL) sensor, TDC sensor, throttle angle sensor, coolant temperature sensor and MAP sensor.

The ECU contains memories for basic ignition timing at various engine speeds, manifold pressure and coolant temperature. When these conditions have been processed, ECU sends signals to ignitor unit to control ignition timing.