Electronic ignition control apparatus

An electronic ignition control device for determining and maintaining a vehicle at the optimum spark advance for different ranges of crankshaft rotation speeds and ratios of air intake to crankshaft rotation speed. Signals indicating a range in which the instantaneous rotation speed falls and a range in which air intake/speed ratio falls define a ROM address at which is stored an optimum spark advance angle for that combination of ranges. The signal indicating the stored angle is applied to a discriminator which also receives inputs from a crank switch monitor, a throttle switch monitor and a coolant temperature sensor. When cranking or idling is detected, the discriminator substitutes a cranking advance or idling advance angle for the stored optimum advance angle signal.