Cars Simplified: Everything Automotive Explained

Coil Packs

Modern engines use ignition coil packs instead of a distributor. The coil converts the low voltage of the car battery into the thousands of volts needed to create an electric spark jump the gap in the spark plugs to ignite the fuel.

Coil Pack Layouts

While all coil packs have the same basic electronics, some manufacturers build them differently than others. For example, some modern GM-built V6 engines have three coil packs which manage two spark plugs each, while modern Ford V6 engines sometimes use a single coil pack for all the spark plugs. Many inline-4 cylinder vehicles built in Japan use one coil per spark plug, and the coils sit right on top of the spark plugs, eliminating spark plug wires. These are referred to as coil-on-plug or COP, and are used on a majority of modern engines.

The positive side to having multiple coil packs is that if one goes bad, you can just replace that one, instead of the whole ignition coil unit. If an ignition coil went bad on a single coil distributor system, it would prevent the engine from running at all, while a milti-coil system losing one coil would just keep one cylinder from firing.

Waste Spark Systems

Some systems which have one coil pack for every two cylinders utilize a waste spark system, where the coil pack will cause two spark plugs to fire when only one needs to be firing. One plug sets off the combustion after the compression stroke, while the other plug fires safely just after the exhaust fumes are vented out.