Working on a coil on plug system can be pretty frustrating for mechanics. So, if you're trying to diagnose a no-start or misfire, how do you know if that spark plug coil is firing? Is that even your problem? This video will show you two methods for troubleshooting the misfire problem. The first quick little test involves a coil-on-plug adapter (tester). Keep watching for the second method. This works for almost all vehicles.