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Misfire CEL, but runs OK. P301 and P304 - 986 Forum - The Community for Porsche Boxster & Cayman Owners

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YOUR RESEARCHMisfire CEL, but runs OK. P301 and P304 - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Leading reported evidence

Clean mass air flow sensor

Performed · outcome unconfirmed

No successful repair reported for this finding.

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Reported fixes: 0
Unsuccessful attempts: 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 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
MAF was cleaned recently so was TB.
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Misfire CEL, but runs OK. P301 and P304 - 986 Forum - The Community for Porsche Boxster & Cayman Owners

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Leading evidence: 'Clean mass air flow sensor' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Clean mass air flow sensor' (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.

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Replace spark plugs and coils supposedly

Performed · outcome unconfirmed

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
Spark plugs and coils supposedly were replaced about 15k miles ago.
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Misfire CEL, but runs OK. P301 and P304 - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Frequently discussed actions (2)

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

Clean mass air flow sensor

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
MAF was cleaned recently so was TB.
Original post Read captured discussion
Misfire CEL, but runs OK. P301 and P304 - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Replace spark plugs and coils supposedly

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
Spark plugs and coils supposedly were replaced about 15k miles ago.
Original post Read captured discussion
Misfire CEL, but runs OK. P301 and P304 - 986 Forum - The Community for Porsche Boxster & Cayman Owners

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.

1 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.

986Forum: 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: 20261026T183130Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources

POST 1 / ORIGINAL POSTEROriginal post

It happens occasionally. Most of the time in the following situation. I have been driving for a while, engine is well warmed up (excess of 30 miles highway on a warm day). Slower traffic builds up, I cruise behind, 5th gear, maybe 50-65 mph. Once the road opens up, drop to the 3rd and floor it, revving it up to nearly 6000 rpm. CEL flashes a few times and then disappears. Not sure if in the beginning or by the end of the pull. The first time I thought I hit the rev limiter, but no - that is not the case. Scan reveals PENDING codes: P300 (general), P301, and P304 - cylinder 1 and 4. If I recall correctly front of the engine, right behind my back. I watch the car and it is all fine. The codes clear on their own after a while. Now, it happens only occasionally. I can drop to the 3rd maybe 10 times and all is good until just one time. Weather? Warm. About 25 C, engine temp 82 C. No AC. When I drop to the 3rd, I blip the gas to match the revs and then clutch it and pull. It starts OK, runs smooth. MAF was cleaned recently so was TB. TB had a bit of residue, not a lot. Enough to see on the glove. MAF looked clean. Both OEM. Car has 115k miles. 2003 2.7 MT Spark plugs and coils supposedly were replaced about 15k miles ago. Petrol is good, fresh few tanks. So - any ideas before I start looking into the spark plugs/coils? I would think that it would maybe misfire on cold, sputter or so if the coils are weak or spark plugs are bad. It drives just fine cold or hot.

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