Distributor: Description and Operation

ELECTRONIC IGNITION SYSTEM (VIN J)


The Electronic Ignition (El) system uses a "waste spark" method of spark distribution. Each cylinder is paired with its opposing cylinder in the firing order, so that one cylinder on compression fires simultaneously with its opposing cylinder on exhaust. Since the cylinder on exhaust requires very little of the available voltage to fire its plug, most of the voltage is used to fire the cylinder on compression. The process reverses when the cylinders reverse roles. There are four coils for the electronic ignition.

Components of the El include a coil pack, electronic ignition control module, camshaft sensor, crankshaft reluctor ring, crankshaft sensor and the ECM. The coil pack on the El consists of four separate, interchangeable, ignition coils. Four coils are used and each coil fires two cylinders. The electronic ignition control module is located under the plenum and is connected to the ECM. The electronic ignition control module controls the primary circuit to the coils, turning them "ON" and "OFF." It also controls spark timing below 400 RPM. If the ECM bypass circuit becomes open or grounded refer to Ignition Systems/testing

The crankshaft sensor inserts through the right side of the crankcase at mid engine, in proximity to the crankshaft reluctor ring. Notches in the crankshaft reluctor ring trigger the magnetic pickup sensor to provide timing information to the ECM. The camshaft sensor provides a cam signal to identify correct firing sequence, and the crankshaft sensor signals to trigger each coil at the proper time.

The ECM controls timing using crankshaft position, engine load, engine temperature, intake air temperature and atmospheric pressure.