Spark plugs play the crucial role of powering your vehicle’s pistons. These spark plugs are responsible for creating those tiny explosions in your vehicle’s engine which in turn powers the pistons to move up and down. In order to work though, these spark plugs will require a small electrical charge. If the wires that they are connected to fails, then the spark plugs will not work. There are different signs that shows that you have a bad spark plugs. These includes poor acceleration and decreased fuel efficiency. Also, if the vehicle’s engine is cranking but is not starting, then the problem may be with the spark plugs as well.