8 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHRough idle, but only on startup when the engine is warm?
Reported or suspected cause
vent line just
Reported cause
No successful repair reported for this finding.
1
Identified cause
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Suspected cause
0
Reported fixes
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Reported cause
However, in my case it was the vent line just to the left of the throttle body; part no.
Rough idle, but only on startup when the engine is warm?
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Leading evidence: 'vent line just' (1 discussions report identifying this cause; no attributable repair resolution). Across 1 matching discussions, the most frequently mentioned possible cause is 'vent line just' (1 discussions; 1 report identifying it and 0 suggest it). The most frequently discussed action is 'Clean not long ago though' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
Source reports, not a diagnosis or a success probability. Counts refer to discussions and can overlap.
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
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Performed · outcome unconfirmed · Original poster
MAF and throttle bodies cleaned not long ago though.
Rough idle, but only on startup when the engine is warm?
Replace mass air flow sensor
Suggestion or failed attempt
No successful repair reported for this finding.
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Reported fixes
0
Unsuccessful attempts
1
Discussions
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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 contain suggestions
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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.
Suggestion
I experimented with cleaning, then replacing the MAF, with no change.
Rough idle, but only on startup when the engine is warm?
Run like crap
Suggestion or failed attempt
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
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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 contain suggestions
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0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
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Suggestion
Often it would just run like crap with no error codes.
Rough idle, but only on startup when the engine is warm?
Run position (not start), wait 60 seconds, turn ignition key
Suggestion or failed attempt
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
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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 contain suggestions
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suggestion
Ignition key in, turn to run position (not start), wait 60 seconds, turn ignition key to off.
Rough idle, but only on startup when the engine is warm?
Coverage and how to read this overview
Counts describe captured discussions, not unique people or a diagnosis. Author identities are not reliably stored. Exact duplicate evidence is counted once across matching discussions; one discussion counts at most once per action/state. Multiple repairs reported together remain a combination. Suggestions and failed attempts do not establish a fix. Matches cover whole discussions and can include related faults, model variants and incomplete threads.
8 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.
3 acknowledgements have no verified action link; they do not establish a repair result.
Outcome without a verified action link
Problem went away after the car sat for a bit, cleared it and haven't had anything pop up since.
Bit of an odd issue going on with my 2003 C2. Searched around but can't seem to find the same issue. Car has trouble finding idle, nearly stalls, and bounces around below 600 RPM for about 5-10 seconds on startup. Then the car is 100%, idles normally around 750, power is there, nothing weird. This also ONLY happens when the engine is warm. Cold start is perfect. I'm pretty stumped, can't figure anything that would happen while warm but not while cold. It threw a P0507 a couple months ago, was idling high between autocross runs. Problem went away after the car sat for a bit, cleared it and haven't had anything pop up since. Will pop in to clean air filter, MAF, throttle bodies, and see if there are any glaring vacuum leaks. MAF and throttle bodies cleaned not long ago though. Not sure what else to look at. Thank you
First do an e-gas reset. Do not touch the accelerator pedal during this procedure. Ignition key in, turn to run position (not start), wait 60 seconds, turn ignition key to off. There will be some whirring and clicking sounds from the engine bay while the throttle body re-calibrates. Then start up normally and see what happens.
[QUOTE=DoctorGoalie;17480291]Bit of an odd issue going on with my 2003 C2. Searched around but can't seem to find the same issue. Car has trouble finding idle, nearly stalls, and bounces around below 600 RPM for about 5-10 seconds on startup. Then the car is 100%, idles normally around 750, power is there, nothing weird. This also ONLY happens when the engine is warm. Cold start is perfect. I'm pretty stumped, can't figure anything that would happen while warm but not while cold. It threw a P0507 a couple months ago, was idling high between autocross runs. Problem went away after the car sat for a bit, cleared it and haven't had anything pop up since. Will pop in to clean air filter, MAF, throttle bodies, and see if there are any glaring vacuum leaks. MAF and throttle bodies cleaned not long ago though. Not sure what else to look at. Thank you[/QUOTE
I have the same problem, did you find out what was causing the rough idle and was there a solution?
Far fetched theory but perhaps leaking injectors? Shutting down the engine causes fuel to leak down for a short while to the combustion area in case of leaking injectors. If the combustion chamber is "wet" the combustion process is not working properly. If the car sits over night etc that fuel evaporates and that's why the cold start is ok. Perhaps take a look at the spark plugs - are those wet?
FWIW my car had this symptom a few years ago. It would be either hard to start when hot, or if it would start it would run really roughly, like the engine was wanting to stall. On occasion it would throw P1128 and P1130 codes, but only sometimes. Often it would just run like crap with no error codes. I experimented with cleaning, then replacing the MAF, with no change. However, in my case it was the vent line just to the left of the throttle body; part no. 99611012953. The complete Porsche part is almost $300, BUT, the actual part you need which is just the Bosch valve near the throttle body is only $40. Both parts will come up if you Google search the part no. Its a REALLY easy fix. Probably only took 15 minutes and maybe worth a try given the ease and cost.
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