The function of a spark plug is to produce the sparks necessary to ignite the gas and air in the engine, initiating a combustion reaction that provides energy to run the automobile. Spark plugs are designed to fit perfectly into each cylinder of the motor.
Four-cylinder engines require four spark plugs and six-cylinder engines need six. A V8 engine has eight spark plugs, four on each side of the engine. To locate the spark plugs in any engine, follow the spark plug wires. They are thick and rubbery wires that are usually visible from the top of the engine. Good spark plugs can increase gas mileage and optimize overall performance.