How a Car Ignition System Works

You probably rely on your car for transportation, but do you ever consider its ignition system? Though they have advanced quite a bit since their initial invention, ignition systems are relatively similar between different models of cars. Read on to learn about the basics of your car's system.


Your car's ignition system has one main purpose: to ignite your gasoline. In order to do this, it must conduct electricity from your battery, concentrate it into powerful sparks and time those sparks properly to line up with the needs of each one of your cylinders.

Internal Combustion

Your car converts gasoline into motion by drawing it and air into a chamber, compressing it, then igniting it, which causes it to expand. This pushes a piston which turns your wheels. On the way back, the piston pushes out exhaust, leaving the chamber small and able to be refilled with flammable gasoline and air once again.

The internal combustion engine requires perfect timing to ignite the gas at the right moment when the chamber is at the right size. Your ignition system ignites your gasoline while making sure the timing is right.

Ignition Coil

Your car's ignition coil takes electricity from your battery and uses it to create a spark. This spark, unlike electricity straight from your battery, is strong enough to ignite gasoline. Your ignition coil uses two coils, know as the primary and secondary coil. The primary coil collects electrical power, while the secondary takes that electrical power from the primary coil and sends it to the next part of the ignition system - the distributor.


Each cylinder in your car engine must be ignited at the correct time. Your car's distributor chooses which cylinder to ignite, and when. Your distributor constantly rotates, due to being attached to your rotor. As it rotates, its coil passes contacts at fixed points that surround it, allowing electricity to arc between your distributor and your spark plugs. Each of these contacts is connected to a different cylinder in your engine. Your distributor's cap and rotor are responsible for regulating the timing of the sparks.

Most of these parts are commonly replaced during tune ups, since even small irregularities can result in serious inefficiency.


Most ignition systems work as described above, but some more recent systems do not use a distributor at all. Instead of one connection that rotates to connect with every cylinder, distributorless ignition systems have many stationary coils that are controlled by a computer chip.

This has two main advantages over a distributor. First, it has fewer moving parts, and therefore requires less maintenance and replacement. Second, it allows more precise timing, giving your car engine better mileage.