[j1gilles]

So for the past 3 months I've notice that only my cylinder number 2 plug becomes heavily fouled after only a couple thousand miles.... I've pulled it once a month for the past 3 months and each time I had to install a fresh plug. The carbon fouling is pretty heavy and comes up the threads of the plug a little. The plug is dry in appearance and I have yet to throw a misfire code. All of the other plugs look almost new. Usually I would suspect a rich condition is causing the carbon build up but it is only happening in one cylinder? The plug has never been wet and the cylinder looks dry when I pull the plug so I do not thinks it is a injector issue, so that leaves me with a weak coil...I think? Has anyone ever had a weak coil cause a similar issue without throwing a misfire code? Thanks for your help!

[Ingeniator]

Originally Posted by j1gilles

So for the past 3 months I've notice that only my cylinder number 2 plug becomes heavily fouled after only a couple thousand miles.... I've pulled it once a month for the past 3 months and each time I had to install a fresh plug. The carbon fouling is pretty heavy and comes up the threads of the plug a little. The plug is dry in appearance and I have yet to throw a misfire code. All of the other plugs look almost new. Usually I would suspect a rich condition is causing the carbon build up but it is only happening in one cylinder? The plug has never been wet and the cylinder looks dry when I pull the plug so I do not thinks it is a injector issue, so that leaves me with a weak coil...I think? Has anyone ever had a weak coil cause a similar issue without throwing a misfire code? Thanks for your help!

I hate to state the obvious but have you tried swapping coils. I'd also swap injectors if the coil doesn't solve it. It could be some other things but you know that. Done a compression or leakdown lately?

[j1gilles]

Originally Posted by Ingeniator

I hate to state the obvious but have you tried swapping coils. I'd also swap injectors if the coil doesn't solve it. It could be some other things but you know that. Done a compression or leakdown lately?

I did not swap coils because I never threw a misfire code. The cylinder looks good under the scope, no oil and the car runs relatively smooth so I doubt there is an issue with compression/leakdown. I guess I could swap the coils and see if another cylinder carbon fowls but I already leaning towards a bad coil...I just wanted to get so assurance before I threw in a new coil

[kfrazie1]

I'd guess it's more than likely an injector issue.

[robc1976]

I say a leaky injector

[Ingeniator]

Originally Posted by j1gilles

I did not swap coils because I never threw a misfire code. The cylinder looks good under the scope, no oil and the car runs relatively smooth so I doubt there is an issue with compression/leakdown. I guess I could swap the coils and see if another cylinder carbon fowls but I already leaning towards a bad coil...I just wanted to get so assurance before I threw in a new coil

I doubt it is the coil that is why I suggested changing it. I agree with everyone else that it is likely the injector. Start the car cold shut it off pull plugs it is probably wet. My bet is it is a injector spray pattern issue. If not I would check leak down/compression it could always be valve seals.

[volcom8190]

Its a bad injector, i had the same problem on my car, although it ran a bit rough on cold starts until I fixed it.

[j1gilles]

Originally Posted by volcom8190

Its a bad injector, i had the same problem on my car, although it ran a bit rough on cold starts until I fixed it.

That's what I was waiting to hear... I did pull the plug after a cold start and it was slightly wet. Going to order an injector today. Thanks for your help!

[j1gilles]

Originally Posted by Ingeniator

I doubt it is the coil that is why I suggested changing it. I agree with everyone else that it is likely the injector. Start the car cold shut it off pull plugs it is probably wet. My bet is it is a injector spray pattern issue. If not I would check leak down/compression it could always be valve seals.

Plug was a little wet after a cold crank and start this morning. I'm going to replace the injector. Valve seals would cause oil fouling and I had my intake off a few weeks ago and the seals looked good. Plus I'm only at 39k

[shawntech]

My plugs after 5k miles are carboned up at the round base and first 1-2 threads on cylinders 2-6. I have a rough idle at cold start and its jerking/stuttering on shifts the first 2 miles from cold. It's getting all new injectors tomorrow which hopefully solves the problem. It has done this for several months without a single misfire or other fault.

[Jeff@TopGearSolutions]

Leaky injector

[j1gilles]

Originally Posted by Jeff@TopGearSolutions

Leaky injector

Thanks Jeff... I pulled a plug after the car sat over night and saw free standing fuel in cylinder numbed 2 and a nice cloud of smoke for a few seconds after the car started. The injector must leak down over night and when not firing. I ordered an injector today.

[ucdbiendog]

Originally Posted by Ingeniator

I doubt it is the coil that is why I suggested changing it. I agree with everyone else that it is likely the injector. Start the car cold shut it off pull plugs it is probably wet. My bet is it is a injector spray pattern issue. If not I would check leak down/compression it could always be valve seals.

thanks for that tip, gonna try that myself!

[BlackBB6]

Originally Posted by j1gilles

Thanks Jeff... I pulled a plug after the car sat over night and saw free standing fuel in cylinder numbed 2 and a nice cloud of smoke for a few seconds after the car started. The injector must leak down over night and when not firing. I ordered an injector today.

Change your oil asap, I had the same issue you're having and my oil was contaminated.

[j1gilles]

Originally Posted by BlackBB6

Change your oil asap, I had the same issue you're having and my oil was contaminated.

Will do... Thanks

[shawntech]

reporting back, mine had shaking at start going into reverse and random jerking/bucking at part throttle while cold. Removing the plugs didn't reveal any raw fuel, however there was carbon deposits at the base. I never had a fault code for anything, ever. all injectors were replaced Monday and I'm happy to report it runs smooth as silk cold, I can't tell it's running without gripping the wheel firmly, lowend power is dramatically increased 1000-1500rpm and mpg is up too.

Keep in mind my car already had new plugs and was walnut blasted a couple months ago when starting this journey of trying to resolve the cold start problems, so I'm sure that helps.

Bottom line, when you've done everything else and have no faults... it's always the injectors.