Ignition Coil: Description and Operation

Coil Pack:

The coil is turned ON (coil charging) by the Ignition Control Module (ICM), then turned OFF, firing two spark plugs at once. One is for the cylinder which is to be fired (on compression stroke) and the other goes to the mating cylinder which is on the exhaust stroke. The next time the coil is fired, the situation is reversed. The next pair of spark plugs will fire according to the engine firing order.

Repetitive spark is used to improve idle stability. It is enabled by the Powertrain Control Module (PCM) program below 1000 rpm. If in the repetitive spark mode after the first spark is sent to a pair of spark plugs, the plugs will be re-struck up to three more times very quickly. The repetitive spark primary waveform can be seen using a engine analyzer with Electronic Ignition (EI) capability.

NOTE: The required tachometer adapter (Rotunda 007-00061) is compatible with all Ford EI vehicles and is also compatible with the repetitive spark mode. A standard tachometer may not be compatible with this vehicle.