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Misfiring Only When Hot & at Idle

jrm_gti

New member
09 Tsi Gti, 118k. Car starts up and runs fine for a while, but like clockwork when nearing 40 minutes of driving and coming to a stop or fully stopped, I get a flashing CEL. RPMs drop a bit then go back up as well, Obdeleven shows misfire all cylinders and always misfire on cylinder 1&4.

Its weird, as long as my commute is under 40 minutes, I get no misfiring at all. Car runs great under any kind of throttle. Replaced spark plugs and pcv. I do plan on replacing coils and have a valve cleaning done.

Any help, or insight is appreciated.
 
Last edited:

Carlosfandang0

Autocross Newbie
I wouldn’t focus on the 40 minute part! Try moving the coils around and see if the consistent 1 and 4 move to 2 and 3, you should in this situation change the coils especially if the consistent fault moves when you swap them around but I’d say it’s most likely carbon build up though or possibly injectors but less likely.


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mataempat

Passed Driver's Ed
Maybe of some help or not. I have a different engine that yours. It's a 1.4 TSI CAVD. I've had the same exact issue for the past year or so. Albeit only on Cylinder 1.

Carbon cleaning with walnut blasting solved the issue.
 

indosilver

New member
Coils are about $100 for a set, i would just get a fresh set of coils and a fresh set of plugs. it's the cheapest option anyways and most likely the cause of your issues :)
 

DallasDub94

Go Kart Newbie
HsTuning sells the coilpacks and spark plugs bundled. 94.99 for a set Red tops by themselves if I remember correctly.
 

jrm_gti

New member
I did try swapping coils around and still get the same result. But I will throw in some new ones anyway.

Mataempat, I am thinking this is my problem. Car has 118k and I'm not sure if a carbon cleaning was ever done by the previous owners .

Car still has the original intake manifold too, not the updated one. Prob going to have to replace it , and see how those injectors are holding up as well.

Thanks for all the replies, I'll try to keep this updated.
 

FriggenT1

Banned
I did try swapping coils around and still get the same result. But I will throw in some new ones anyway.

Mataempat, I am thinking this is my problem. Car has 118k and I'm not sure if a carbon cleaning was ever done by the previous owners .

Car still has the original intake manifold too, not the updated one. Prob going to have to replace it , and see how those injectors are holding up as well.

Thanks for all the replies, I'll try to keep this updated.

I'd try something simple like the gumout valve cleaner spray. Use it through the temp sensor hole, if you can tell any difference at all, that's likely your issue
 

Carlosfandang0

Autocross Newbie

Carlosfandang0

Autocross Newbie
Excellent, check this out...notice the carbon that comes out and he also has borescope pics https://youtu.be/hHF-Jdw0eto



When I used the wynns product I got a lot of carbon out of the exhaust (far more than in the video) and it ran much much better once I was done, for unrelated issues I’ve since then had a new head and inlet manifold and PCV so I should be good for a while but I intend to use the cleaner again soon as a preventative measure, like he says in the video if it’s done on a regular basis there should never be any large build ups and a full clean will not be necessary, I’ve only used the wynns stuff though so can’t really make a judgment on other products.


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FriggenT1

Banned
When I used the wynns product I got a lot of carbon out of the exhaust (far more than in the video) and it ran much much better once I was done, for unrelated issues I’ve since then had a new head and inlet manifold and PCV so I should be good for a while but I intend to use the cleaner again soon as a preventative measure, like he says in the video if it’s done on a regular basis there should never be any large build ups and a full clean will not be necessary, I’ve only used the wynns stuff though so can’t really make a judgment on other products.


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I'll have to look for it in the U.S. and give it a try
 
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