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The following article has been donated by Marcie E. Stoker of Everdrive.com, a leading used auto parts, Ford parts, and Honda parts provider.

An Ignition System's Insides and Outs

The purpose of your car's monstrous ignition system is to time a spark that ignites gas at the precise moment needed to power your engine. Several different parts work together to make this happen. Your car's engine is basically a huge pump. Air and gas are pumped in, producing energy that turns the tires and moves the vehicle. That's an oversimplification, but sufficient for learning how the components of the system work. Below, I'll briefly describe the parts involved and take you through the process of igniting the gas and powering your engine.

Parts And Their Jobs

Your ignition system is comprised of spark plugs, a distributor (and cap), rotor, and coil. The coil is what transforms an electrical current from your car battery into a spark. When the coil successfully creates a spark (and it needs to be potent enough to actually ignite the fuel), the spark is transferred to your car's distributor. The reason it's called a distributor is because it spins and allocates the sparks from the coil to multiple spark plugs. It does that through the rotor.

The rotor spins with the distributor and contacts the cylinders of the engine. When it does this, it transfers the sparks to the spark plug wires. At this point, the spark has nearly traveled to where it needs to be. Each of the spark plug wires is attached to the distributor cap through its own contact point. Those wires send the spark directly to the spark plugs which are mounted in your car's cylinder head. When the gases from the fuel flow into the cylinder, the spark ignites them, causing combustion.

The process I've just described happens over and over, tens of thousands of times while your car is in operation.

A Seamless System

Your ignition system is most effective when the sparks are precisely timed. In the past, this was done by employing a points-and-condenser module to tell the distributor when to allocate the sparks to the spark plugs. Today, most cars are equipped with computers (called ignition modules) that control the timing. They do so by notifying your car's engine control unit about the placement of the pistons. If an ignition module fails, it's usually necessary to replace it.

Over the past few years, manufacturers have begun experimenting with "distributorless" ignition systems. Rather than a single coil creating the sparks needed to ignite the fuel, each spark plug has its own coil. That effectively eliminates the need for the distributor. It's still considered a young technology, but holds significant promise.