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Understanding How Your Car’s Ignition System Works

Your vehicle’s ignition system is responsible for generating the spark that ultimately turns your wheels. To understand how this occurs, it’s worth reviewing what happens in your engine.

Your engine has a number of cylinders (i.e. 4, 6, 8, etc.). Each cylinder has a combustion chamber to which air and fuel are sent. Once the air and fuel have entered the chamber, the intake and exhaust valves close, and the mixture is compressed and ignited. The resulting explosion pushes a piston within the chamber downward, which generates force on your car’s crankshaft. That force causes the crankshaft to turn. As it does, it turns your wheels.

A spark is needed in order to ignite the air-fuel mixture within the combustion chamber. That spark originates from your ignition coil.

Your Ignition Coil

Most people mistakenly believe their car’s battery generates sufficient voltage to produce a spark for each cylinder’s combustion chamber. In reality, it doesn’t. Instead, the ignition coil receives power from the battery and converts it into a powerful spark. It accomplishes this through coils known as windings.

A primary winding gathers the necessary power from the battery. A secondary winding transfers that power to your vehicle’s distributor.

Your Distributor

Your vehicle’s distributor is responsible for distributing the sparks sent from the ignition coil to each of your engine’s cylinders. It accomplishes this through a rotor. The rotor is connected the distributor’s shaft and spins, making contact with a number of terminal points in the distributor cap. The number of points within the cap reflects the number of cylinders in your engine.

As a connection is made with the contact point, the distributor sends the spark to the corresponding spark plug wire.

Creating The Explosion

Each plug wire is connected to a spark plug. The spark plug sits in the cylinder head at the top of a combustion chamber. When the plug wire receives a spark from the distributor, the spark travels through the spark plug and ignites the air-fuel mixture within the chamber.

The process described above occurs thousands of times each minute while you’re on the road. Precise timing in the delivery of the sparks is critical to your engine’s performance. This is usually controlled by your vehicle’s engine control unit (ECU).

If the distributor begins to fail, the timing of the sparks can become erratic. That will affect the efficiency of your car’s engine and lower your gas mileage. If the erratic timing persists while your engine is under heavy load, it can result in spark knock. That can lead to expensive engine damage.

Your car’s ignition system relies on a number of parts that suffer wear and tear with use. Plan to eventually replace the ignition coil, distributor, cap, rotor, spark plugs, and plug wires to maintain your engine’s performance.

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