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RPMs going up and down at idle

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7 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW

Discussion summary

YOUR RESEARCHRPMs going up and down at idle

Leading reported evidence

Check codes

Performed · outcome unconfirmed

No successful repair reported for this finding.

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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 performed work without a confirmed outcome
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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.

Performed · outcome unconfirmed · Original poster

Dealer has checked for codes.

Original post Read captured discussion
RPMs going up and down at idle
Frequently discussed work

Check ac

No successful repair reported for this finding.

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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 · Original poster

I will check the ac but 1second cycling seems a little fast for an ac problem.

Original post Read captured discussion
RPMs going up and down at idle
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Leading evidence: 'Check codes' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Check ac' (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.

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1 matching discussions · 7 captured posts examined · 0 partial discussions

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Check ac

Suggestion or failed attempt

No successful repair reported for this finding.

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Reported fixes
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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 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 · Original poster

I will check the ac but 1second cycling seems a little fast for an ac problem.

Original post Read captured discussion
RPMs going up and down at idle

Check fuel trims

Suggestion or failed attempt

No successful repair reported for this finding.

0
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 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

I'd maybe have the dealer pull any codes that might have been thrown and check the fuel trims.

Original post Read captured discussion
RPMs going up and down at idle
Frequently discussed actions (3)

These are separate views of the same evidence. Frequency alone does not establish a fix, and these counts must not be added together.

Check ac

No successful repair reported for this finding.

0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
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 · Original poster

I will check the ac but 1second cycling seems a little fast for an ac problem.

Original post Read captured discussion
RPMs going up and down at idle

Check codes

No successful repair reported for this finding.

0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Discussions that performed work without a confirmed outcome
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.

Performed · outcome unconfirmed · Original poster

Dealer has checked for codes.

Original post Read captured discussion
RPMs going up and down at idle

Check fuel trims

No successful repair reported for this finding.

0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
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

I'd maybe have the dealer pull any codes that might have been thrown and check the fuel trims.

Original post Read captured discussion
RPMs going up and down at idle
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.

7 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.

1 acknowledgements have no verified action link; they do not establish a repair result.

Outcome without a verified action link

After warm up it idles at normal rpm then drops about 200 rpms then back to normal at about 1 second interval's.

Original post Read captured discussion

No unique explicit quoted action; no causal link assigned

Generation: 20261027T184158Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources

POST 1 / ORIGINAL POSTEROriginal post

2000 996 with 65000 miles. At cold start up engine idles normal. After warm up it idles at normal rpm then drops about 200 rpms then back to normal at about 1 second interval's. When the fuel tank is full the swings are greater 100 rpms over normal to 300 rpms below. I am thinking fuel delivery, maybe fuel pump because the amount of fuel in the tank seems to have an effect. Are the fuel pumps inside the fuel tank? Local Porsche dealer says it is running rich other than that they have been of little help. I am open to any ideas.

POST 2Original post

To eliminate the obvious, AC is switched off? An undercharged AC system compressor rapidly cycling on and off might cause this... I'd maybe have the dealer pull any codes that might have been thrown and check the fuel trims. Possible that the 02 sensors or MAF sensor is drifting a bit out of spec and the ECU is trying to compensate.

POST 3Original post

My bet would be on the air conditioner. It took me a while to figure that one out when I saw rpm cycling.

POST 4 / ORIGINAL POSTEROriginal post

I will check the ac but 1second cycling seems a little fast for an ac problem. Dealer has checked for codes. No help. Thanks for your input.

POST 5Original post

Regeneration valve. Your comment about the fuel level makes this suspect. Link

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