ignition coil for all vehicle types

Coil pack for cars: find out more! How to choose, when to change , and how much they cost

An ignition coil is a unit designed for converting low-voltage current into high-voltage. High-voltage current is then supplied to a spark plug, which generates a spark between its electrodes and ignites the air-and-fuel mixture.

Types

• Distributor and can-type coils. They form one spark per one crankshaft rotation. It is supplied to the spark plug in the corresponding cylinder with the help of an ignition distributor. These parts are inexpensive and reliable. They can feature a built-in output stage that can limit the current supplied by the coil, switch it off when it’s overheating, detect a short circuit, and perform computer diagnostics of the unit.
• Dual-spark (distributorless). They generate two sparks for a pair of cylinders at once. But the air-and-fuel mixture is ignited only in one cylinder, another spark is “wasted”. Such devices are more compact. They work without a distributor and don’t require synchronization with a camshaft. However, they are only suitable for engines with an even number of cylinders.
• Coil-on-plug (pencil). There is one coil per each spark plug, usually mounted directly on top of it. However, in some engines, they can be connected via high-voltage cables. They provide stable and powerful spark formation, which ensures complete and even fuel combustion. They allow shutting down one of the cylinders, if necessary, to avoid damaging sensors and other units. They require synchronization with the camshaft. Several coils can be combined in so-called coil packs. They guarantee the lowest ignition voltage loss.
• Dual-coil. Such devices combine two ignition coils in one casing. They are connected directly to the corresponding spark plug. They allow reducing the ignition lag and adjusting the ignition timing more accurately.

Operating tips

Never hang an ignition coil by its wires during inspection or replacement of ignition system components. Do not attempt to disassemble it or detach the connector. Do not apply extra force when attaching the electrical connections. First, make sure that you’ve connected all the wires correctly. Never hit the ignition coil casing. Tighten the threaded joints with a torque specified by the car manufacturer. It is not recommended to apply oils and sprays onto electrical contacts: this may increase the connection resistance or cause a short circuit.

Before washing the engine compartment, cover all the electrical components with plastic bags. Remove leaks from the engine and expansion tanks for technical fluids.

Symptoms of malfunctions

You can usually notice the signs of ignition coil short circuit during visual inspection. As a rule, black spots, cracks and longitudinal streaks can be found on its surface. In this case, part of the current will be diverted to the casing, therefore spark formation in one of the cylinders will be failing. The engine starts misfiring, especially in rainy weather. When the part fails completely, misfiring occurs regardless of environmental humidity level. Vehicle dynamics becomes worse. In cars with a single can- or distributor-type coil, the engine might not start at all when it fails.

Causes of malfunctions

The ignition coil often breaks down due to overheating. This can be caused by cooling system malfunctions, improperly adjusted ignition timing, putting the vehicle under excessive loads. Extreme temperatures can melt the casing and cause the contacts to burn or short-circuit.

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Useful information on functions, causes of malfunction, diagnosis and replacement intervals

• Ignition module: failure symptoms, problems, and testing