16 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHCEL under acceleration with #5 cylinder misfire
Reported repair
Replace of the coils and still nothing
Reported resolution
1
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that report a fix
1
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0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Reported fix
Replaced all of the coils and still nothing. Discovered my cats were clogged and that fixed my problem.
Leading evidence: 'Replace of the coils and still nothing' (1 discussions report resolution; 0 report an unsuccessful attempt). Across 1 matching discussions, the most frequently mentioned possible cause is 'lifter stuck' (1 discussions; 1 report identifying it and 0 suggest it). The most frequently discussed action is 'Replace of the coils and still nothing' (1 discussions). For that action, 1 discussions report a resolution and 0 report an unsuccessful attempt. The most frequently reported fix is 'Replace of the coils and still nothing', supported by resolution reports in 1 discussions. These are forum reports and suggestions, not a confirmed diagnosis.
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Discussions that report identifying a cause
1
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Reported cause
Turned out to be a lifter stuck on the high side for vario cam.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that performed work without a confirmed outcome
1
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Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that suspect a cause
1
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Suspected cause
No way you should have to remind the tech of this but there have been misfires traced to a coil.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that contain suggestions
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Suggestion
One easy way to test this is to disconnect the cats and run the car for a bit.
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Suggestion
It was very confusing because the coils were replaced, variocam was checked, and it was always one cylinder (sometimes two) that would report the error.
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16 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
0 evidence records excluded for query context · 0 excluded by outcome qualification · 0 adjusted by outcome qualification.
0 acknowledgements have no verified action link; they do not establish a repair result.
Generation: 20261026T083035Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
Hi all - been about 18 months since I left 996 land for 997 land. I still miss the camaraderie of this bunch, so I troll occasionally to see what's up.
A friend of mine and I were at lunch today and he's got a 2004 C4S. Under hard acceleration north of 3500 RPM his CEL light comes on and if he accelerates hard again it starts to flash. He's had it in to be looked at, but the techs are still researching the cause. The diagnostic readout indicates a misfire in cylinder 5, but the root cause has not been determined.
Has anyone else had this problem or know what the root cause might be?
Any and all help appreciated. Oh, btw, it is a Tiptronic.
Thanks much,
Kurt
Was it raining today or did he recently wash his car?
Due to the orientation of the intake, water can get in there. Cylinder sucks it in, engine misfires, CEL lights up like a Xmas tree...
If this was the case, clear the code and all will be well.
Check and see if the cats are plugged. I was getting random CELs for a while. Replaced all of the coils and still nothing.
Discovered my cats were clogged and that fixed my problem.
laz74: Weather was dry and car had not soaked at any time when it occurred.
fpena944: If it is the cats, why would the CEL readout be a misfire in a cylinder?
This is not a diagnosis just stating a possibility. I had a similar issue with my 2004 C2 a few years back. Code was for a misfire in cylinder 6 but I also had the "drive to workshop" warning. Turned out to be a lifter stuck on the high side for vario cam. In addition to the CEL it ran extremely rough.
Ahsai and Silotwo - great suggestions. Silotwo - he got the "drive to workshop/dealer" warning as well. Might be onto something here. Will check it out!
Thanks much.
With mine the cat was plugged just on one side. It would perform fine under 4k RPM but once I hit 5k RPM it would always come back as a misfire. It was very confusing because the coils were replaced, variocam was checked, and it was always one cylinder (sometimes two) that would report the error.
I never received any error codes except for the misfire.
One easy way to test this is to disconnect the cats and run the car for a bit. If it doesn't do it then you might be on to something.
I would agree with Ahsai and Silotwo.
Reads like at least one intake valve lifter in cylinder 5 is not working right.
Is there any noise, valve ticking? Does the engine run/idle rough?
There is a road test -- takes two techs -- to check out the valve lift function. One tech drives the car the other monitors O2 sensor readings and observes any abnormal reading that indicates one or more valves are not opening completely due to a bad lifter.
Just be sure the plug and coil have been eliminated. No way you should have to remind the tech of this but there have been misfires traced to a coil. While the coil was not bad its connection at the wiring harness was marginal and this accounted for the misfire.
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