· Premium Member
Plugs and wires and cap, check compression during that job, yes, that is the proper thing to check first. From there, if the miss goes away after the tune-up, then yes, problem fixed, if it doesn't, or if the compression is low in one or two cylinders, squirt a couple drops of oil into each cylinder and see if that stops the miss by raising the compression (sealing the rings better), or if it continues, next thing to check is then the fuel injectors themselves. With this many miles, and if the miss continued with the oil in the cylinders, rings can be ruled out the greatest, but time to pull the heads and see if there is a burned valve. At this time, the injectors themselves need to be checked and cleaned, what with the fuel/air ratio maintained through the electronics, good chance the problem of a burned valve (if it is that), was the restult of a bad, sticky, dirty, injector.