Ignition Parts

Merely pumping the fuel into the engine won’t cause it to run. Firstly, the fuel should have the right amount of air to supply oxygen. Secondly, there should be an external cause to initiate the burning. In internal combustion engines, the ignition system is responsible for the burning of the fuel at the right moment.

Cars use electric sparks to ignite the fuel-air mixture inside the engine cylinder. But because there are multiple cylinders in engines that should be ignited with precise timing, we need a dedicated ignition system to carry out this task. Maintaining this system in good condition is vital for engine health. A faulty ignition system reduces fuel efficiency and also causes wear and tear on the engine parts. There are a few components to this system, and if any of them stops working, the entire car will stop working. But replacing the ignition system components is not that expensive. This article will give you a basic understanding of the various components of this system.

Beginner’s guide to ignition systems

The ignition provides the initial heat for the fuel to burn. Different types of ignition systems use different methods to do this. But the most common among all of them is the electric coil ignition. Magneto ignition, which is a recent improvement in the ignition technology, is, in fact, a modification of the electric coil type ignition. There are few telltale signs of a bad ignition. Like an engine failing to start or misfiring. Knowing about the main components of the ignition system will help you diagnose the problem and buy the right component to replace or rework the ignition.

Ignition coil

You know that the only source of electricity in a car is the car battery. But the voltage rating of a typical car battery is from 12 to 15 volts. This is not enough to start a controlled explosion inside the engine. That’s when the ignition coil comes into the picture. Ignition coil works similar to a voltage transformer in an electrical system. But in a car, it has to be compact. An ignition coil houses thousands of turns of copper wires that are insulated from each other and are wound around a magnetic core. The inside of the coil assembly will have oil for cooling.

Spark plugs

It is the spark plug that carries the current into the engine cylinder. There will be multiple electrodes inside an engine cylinder. As the spark jumps across the electrodes, the fuel-air mixture catches fire and starts the explosion. Because of their working, spark plugs are more susceptible to corrosion. With time, the gap between the electrodes widens inside the cylinder. When the gap gets too large, that’s when the spark plug starts to fail. This will take a toll on fuel efficiency. That’s when you will notice the reduction in power output of the engine and sound of engine misfiring.

Ignition distributor

These days, there are no cars that have only one cylinder. Cars with four, six and eight cylinders are the norm. Among insanely powerful race cars, you might even come across 16-cylinder engines, but that is a rarity. More cylinders add more complexity. One of the challenges is to synchronise the firing of spark plugs between all the cylinders. In normal passenger cars, that is achieved by an ignition distributor that will control the flow of current the spark plugs. In modern cars, CKP and CMP sensors are replacing traditional ignition distributors.

Distributor rotor

The rotor sits inside the head of the ignition distributor. While the distributor has the connection to the spark plugs, the rotors receive the high voltage electrical supply from the ignition coils. The rotation of the rotor is synchronised to the rotation of the engine. As the rotor moves, the metal contacts on it brushes against the distributor contacts and constantly makes and breaks the connection with the distributor terminals. When the rotor makes contact with a terminal, the spark plug corresponding to that particular terminal fires.

Ignition system vs starter

A starter is a lot different from the ignition system. While an ignition system is responsible for the continuous running of the engine, a starter only works when the ignition key is turned (replaced by a button in modern cars). The engine needs an initial push from the idle position for it to start. Everything else in the engine, including the ignition system, works synchronously with the rotation of the engine. It is the sound of the starter motor that you hear when you turn the ignition key. After the engine is set in motion, the ignition system burns the fuel and ensures the continuous running of the engine.