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Turning on the car ignition is the first thing you do after putting on your seat belt. Once the engine is fired up and idling, it is vitally important that the ignition system on your car works in perfect harmony with the rest of the engine. ¬That harmony is achieved when the ignition system creates the perfectly timed spark in order to maximise engine performance. If the petrol is not ignited at exactly the right time, the expanding gases cannot do the maximum amount of work, power will fall and gas consumption and emissions can increase.

The most popular engine for cars in the UK is the petrol driven internal combustion engine. Fuel in the form of petrol is put into the car and is converted into the energy we need, and the more petrol we put into the engine by pressing the gas pedal, the faster we go. The term 'internal combustion' basically means that the fuel is burnt inside a combustion chamber within one of the cylinders of the engine. A combustion chamber is the area above the piston where a fuel and air mixture is introduced and ignited by the spark plug. When this mixture of petrol and air is ignited, it explodes with tremendous power and it's this explosive power that pushes the car forwards along the road. In the diagram overleaf, spark plug (D) must spark at the right time so that the gases above the piston (F) in the combustion chamber (M) within cylinder (K) are ignited.

Image source http://auto.howstuffworks.com/ignition-system1.htm