Ignition Coil: Description and Operation

Fig.16 Ignition Coil - 4.7L Engine:

Fig.17 Ignition Coil Location - 4.7L Engine:

IGNITION COIL
The 4.7L V-8 engine uses 8 dedicated, and individually fired coil for each spark plug. Each coil is mounted directly to the top of each spark plug.

Battery voltage is supplied to the 8 ignition coils from the ASD relay The Powertrain Control Module (PCM) opens and closes each ignition coil ground circuit at a determined time for ignition coil operation.

Base ignition timing is not adjustable. By controlling the coil ground circuit, the PCM is able to set the base timing and adjust the ignition timing advance. This is done to meet changing engine operating conditions.

The ignition coil is not oil filled. The windings are embedded in an epoxy compound. This provides heat and vibration resistance that allows the ignition coil to be mounted on the engine.

Because of coil design, spark plug cables (secondary cables) are not used.

Fig.20 Coil Capacitor (Left Side Shown):

IGNITION COIL CAPACITOR
Two coil capacitors are used. One of them is located near the center of, and on the left side of the intake manifold. The other capacitor is located near the center of, and on the right side of the intake manifold.

The two coil capacitors are used to prevent high-voltage spikes from interfering with the operation of certain powertrain sensors. They are also used to help prevent radio interference.