Car Ignition System Works

The ignition system in your car ignites the fuel inside the engine's combustion chamber at the optimal time in the piston stroke to produce the most power while emitting the least amount of emissions as possible. There are many configurations of ignition systems but all operate on the same principle, create a low energy field and collapse it onto a high energy coil and that transfers the electrical energy into the secondary ignition system, coil wire, distributor cap and rotor (if equipped) plug wires and finally the spark plug.


Typical Ignition System in Operation

This system is triggered by the primary ignition system, this system varies depending on manufacturer but all operate on the same principle, use some kind of low voltage trigger system i.e. crankshaft position sensor, camshaft position sensor. This low voltage system (1.5 to 3.0 volts) is amplified to 12 volts by using a ignition module (amplifier) and then transferred to the primary side of the ignition coil. The ECM (engine control module) controls the engine ignition timing by advancing and retarding the primary trigger signal. In old cars a points, condenser and a vacuum advance unit performed this job.

This ignition coil is a pulse-type it consists, in part, of two coils of wire. These wires are wrapped around two iron cores. Because this is a step-up transformer, the secondary coil has far more turns of wire than the primary coil. The secondary coil has several thousand turns of thin wire, while the primary coil has just a few hundred raps. This allows 40,000 volts or more of voltage to be generated by a car battery.

This electrical signal is generated by the crankshaft position sensor, camshaft position sensor. The ECM calculates spark timing by using the computer system.

Some ignition systems have a coil for each spark plug. This is called Direct Ignition (DI) system, there are no plug wires in this system just individually controlled ignition coils. The amount of coils or spark plugs depend on the number of cylinders the engine is designed with.

The initial power supplied to the ignition system is generated from the battery. All vehicles use an alternator to recharge the battery during normal operation. A low battery can cause an engine not to start even if the engine is cranking over slowly. This is because the vehicle voltage has dropped below 12 volts. If any component of the ignition system is not functioning properly, it can cause an entire ignition system failure. Proper maintenance such as a tune up can help ensure that the vehicle's ignition system operates at peak performance.

Spark Plug in Operation

When an engine misfires under power it is typically caused by the ignition system. To troubleshoot the cause of the ignition system failure scan the ECM for trouble codes and repair as needed. Maintenance to the ignition system includes changing the spark plugs and distributor cap and spark plug wires if equipped. Changing the spark plugs and wires usually is a simple task that most people can perform themselves.