Your should keep your old spark plugs in order when you take them out, so you know which cylinder they came out of. Then you can read what color the porcelain is at the electrode. Compare all of the spark plugs when you get them out, if one is a different color or has more carbon on it than the others then this is a clue to what is going on with your ignition system. And next step, what is going on inside your engine.
Keep Thinking . . .
