Operation

The electronic ignition system does not use the conventional distributor and coil. The ignition system consists of 3 ignition coils, an Ignition Control Module (ICM), a dual Hall-effect Crankshaft Position (CKP) Sensor, an engine crankshaft balancer with interrupter rings attached to the rear, the related connecting wires, and the Ignition Control (IC) and fuel metering portion of the PCM. Conventional ignition coils have one end of the secondary winding connected to the engine ground. However, in this ignition system, neither end of the secondary winding is grounded. Instead, each end of a coil's secondary winding is attached to each spark plug of the 2 cylinders designated to share the coil (1/4, 2/5, 3/6). These 2 cylinders are referred to as companion cylinders, i.e., on top dead center at the same time. When the coil discharges, both plugs fire at the same time to complete the series circuit. The cylinder on compression is said to be the event cylinder and the one on exhaust is the waste cylinder. The cylinder on the compression stroke requires most of the secondary coil's available voltage to fire the spark plug. The remaining energy is used as required by the cylinder on the exhaust stroke. The same process is repeated when the cylinders reverse roles. This type of ignition is called a waste spark ignition system.

On a conventional ignition system the spark plugs tire with the same polarity (forward). If the polarity of the conventional ignition system was reversed, the spark plugs would fire backwards. Since the required voltage to tire the spark plugs backwards is higher, and coil design limited the secondary coil's available voltage, a weak spark or misfire could occur. However, in the waste spark ignition system, the polarity of the ignition coil primary and secondary windings is fixed. One spark plug always fires with normal polarity and its companion plug fires with reverse polarity. The voltage required by each spark plug is determined by the polarity and the cylinder pressure. The cylinder on the compression stroke requires more voltage to fire the spark plug than the cylinder on the exhaust stroke. Because of improved coil design, and increased primary current flow and saturation time, the ignition coils produce a higher secondary voltage - greater than 40 kilovolts (40,000 volts) at any engine RPM. The higher available voltage provides more than enough energy required by the event cylinder, the additional spark plug gap, and the reverse polarity of the waste cylinder.

It is possible for one spark plug to fire even though a plug wire from the same coil may be disconnected from its companion plug. The disconnected plug wire acts as one plate of a capacitor, with the engine being the other plate. These 2 capacitor plates are charged as a spark jumps across the gap of the connected spark plug. The plates are then discharged as the secondary energy is dissipated in an oscillating current across the gap of the spark plug that is still connected. Secondary voltage requirements are very high with an open spark plug or spark plug wire. The ignition coil; has enough reserve energy to fire the plug that is still connected at idle, but the coil may not fire the spark plug under high engine load. A more noticeable misfire may be evident under load as both spark plugs may then be misfiring.