Ignition Coil: Description and Operation

PURPOSE
The Electronic Ignition system controls fuel combustion by providing a spark to ignite the compressed air/fuel mixture at the correct time. To provide optimum engine performance, fuel economy, and control of exhaust emissions, the Powertrain Control Module (PCM) controls spark advance of the ignition system. Electronic ignition has several advantages over a mechanical distributor system.
^ No moving parts
^ Less maintenance
^ Remote mounting capability
^ No mechanical load on the engine
^ More coil cool down time between firing events
^ Elimination of mechanical timing adjustments
^ Increased available ignition coil saturation time

OPERATION
The electronic ignition system does not use the conventional distributor and coil. The ignition system consists of three ignition coils, an ignition control module, a dual hall-effect crankshaft position sensor, an engine crankshaft balancer with interrupter rings attached to the rear, related connecting wires, and the Ignition Control (IC) and fuel metering portion of the PCM.


Ignition Coils
Three separate coils are mounted to the module assembly. Each coil provides the spark for two plugs simultaneously. Each coil can also be replaced separately. A "Waste Spark" method of distribution is used on this system. Each cylinder is paired with its opposing cylinder in firing order so that one cylinder on the compression stroke fires simultaneously with its opposing cylinder on the exhaust stroke. Requiring less voltage to fire the plug on the exhaust stroke, most of the available voltage is sent to the compression stroke cylinder. This process is reversed as the cylinders' roles are reversed.