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I finally got around to swapping my spark plugs and wires in response to a P0303 [cylinder 3 misfire]. The M113s plugs aren't the easiest to change, all tucked away as they are.
But what was really curious was the interesting look of the old plugs.
Isn't that peculiar? Why are the cylinder 3 plugs so clean? It's as if only cylinder 3 plugs were changed recently or just weren't firing.
Well so far so good. I'm unable to reproduce the P0303.
I had that code in the history, exact same cylinder ( no current codes) and was wondering about it as well.
New plugs are planed for this week. Only due to the mileage - 60K since new. Will see how they compare.
Don't jump to any conclusions but the only time I've seen plugs come out that clean like that is when there was moisture in the cylinder. Too lean would have white residue on the plug and too rich would have a brown to black residue. When there is moisture in the cylinder the plugs get steam cleaned.
@MarkCan I'm at 58.8k miles, I havent looked at the maintenance schedule but platinum should be able to go 100k.
@mikefamig I hadn't thought of that, but will check coolant level later.
My thought at the moment is that the #3 fuel injector could be dirty or ready for replacement and the previous owner or dealer took the cheap route on a P0303, just changing the plugs. My current plan is to spy on fuel metrics through my reader and add fuel injector cleaner at the next fill up.
Color of the plug insulator is not the only peculiar thing there. Look at the center electrode - it is not eroded at all, unlike other plugs. I vote for these plugs not working at all. Looks like faulty wiring was the culprit.
Color of the plug insulator is not the only peculiar thing there. Look at the center electrode - it is not eroded at all, unlike other plugs. I vote for these plugs not working at all. Looks like faulty wiring was the culprit.
It makes sense that they would be washed with gasoline if they weren't firing at all.
But I would think that if they weren't firing at all there would be a consistent CEL for a misfire. In my case I saw 3 CELs, cleared them, and they would only reappear on full throttle. I did find a loose spark plug wire and reattached but I thought it was for cylinder 4 (now I'm questioning if I had confused that), but either way I had reattached when I swapped coil packs 3 and 4 to rule them out as the culprits. Even that though, was one loose wire, these are 2 separate spark plugs for a single cylinder.... just feels like the plugs were replaced on this single cylinder.
07-06-2019, 08:44 PM
