Electronic Ignition: Notes

On 4-cylinder engines, electronic ignition ECU controls primary windings of ignition coil using signals from fuel injection ECU based on crankshaft position, engine speed and vehicle speed. Turbo models use a Hall Effect sensor, located in distributor, to determine crankshaft position and engine speed. Non-turbo models use a flywheel sensing permanent magnet generator to determine crankshaft position and engine speed.

On 5-cylinder engines, distributor ignition ECU computes correct timing of each ignition pulse in response to signals from vehicle speed sensor (supplies information on engine speed and crankshaft position), camshaft position sensor (assists control module to determine rate of combustion in cylinders), knock sensors (supply signals indicating engine knock), fuel injection ECU (supplies information on throttle opening, engine load, and coolant temperature, and transmission ECM (supplies signals indicating reduction in torque required prior to gear shift).

On 6-cylinder engines, each cylinder is equipped with an individual ignition coil, eliminating the distributor. ECU computes instant at which each ignition coil must deliver its high voltage pulse. All six coils are controlled by 2 power units.