Spark plugs are an electric device engine and ignites compressed fuel. A spark plug gap is essential in the running of your vehicle. Most spark plugs today come pregapped for easy use. It does help to check though, just in case. If you have a bad spark plug your engine will not run right and will run very poorly. Depending on how many cylinders you have that is how many spark plugs you will have in your vehicle. If you have a V8 engine you will have 8 spark plugs. If you have a 4 cylinder engine you will have four spark plugs. Spark plug wires bring power from the distributor to the spark plug itself. If you have a bad spark plug wire your car may run bad also. It always helps to keep an eye on the spark plugs and spark plug wire.