6 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHP304 misfire
Leading reported evidence
Check / cleared a p304 at each stop
Performed · outcome unconfirmed
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 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
I made 2 stops before returning home and checked / cleared a P304 at each stop.
Leading evidence: 'Check / cleared a p304 at each stop' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Check / cleared a p304 at each stop' (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
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
Again, the car stumbled just off idle at lights, but ran strong and smooth once underway.
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
On my return trip to home base, I pulled over to reset the clock and other things that the battery disconnect messed with.
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
On my return trip to home base, I pulled over to reset the clock and other things that the battery disconnect messed with.
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
Codes cleared and a quick run around the neighborhood felt fine but P304 returned withing a couple of minutes.
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.
Unsuccessful attempt · Original poster
I installed new injectors for all 3 bank 2 cylinders and the problem persists on #4. … Once water temp showed 180+ I ventured slightly past 3000 a few times, but then when the engine returned to idle speed, the CEL returned.
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
Car runs great but during Summer, 2025 it threw 2 random misfire codes from April through October (usually after a wash) shortly after startup but with no rough running detected.
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.
6 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.
2 acknowledgements have no verified action link; they do not establish a repair result.
Outcome without a verified action link
I've wanted a 911 for 45+ years and after a few 'almosts' that didn't work out in 2020, I purchased a 2004 C4S in April, 2025 with just under 84k on the clock.
History:
I've wanted a 911 for 45+ years and after a few 'almosts' that didn't work out in 2020, I purchased a 2004 C4S in April, 2025 with just under 84k on the clock. Previous owner did a bunch of work (no IMS bearing as far as I know so I was going to do that before Spring 2026 wake-up) but no receipts for ignition parts were included. Car runs great but during Summer, 2025 it threw 2 random misfire codes from April through October (usually after a wash) shortly after startup but with no rough running detected. I have "torque" app on an old android phone which can read and clear codes as well as show limited real-time data, and plan to get something more comprehensive (free PIWIS, durametric, other?) as I plan to keep this car. When the CEL has appeared, no performance issues were felt while driving, but the CEL would appear (solid light - no flash) until cleared and then not come back for a long time.
Fast forward to November 9: During a 2+ hour drive on some favorite local roads, I felt some rough running and an occasional CEL (sometimes solid, sometimes flashing). My android battery was dead but when I got home codes were: misfire from cylinders 2, 3, 4, 5. Codes cleared and a quick run around the neighborhood felt fine but P304 returned withing a couple of minutes. Code cleared and then threw P304 again within a minute or 2 but none of the others. A quick review of the 1" stack of receipts from the P.O. showed no coils or plugs so I ordered a set of 6 each while away for a few days, and installed everything this morning (Car had Beru upgrades and Bosch plugs installed but again, no receipts so unknown age / mileage). I had the battery disconnected in hopes of clearing adaptives to be re-learned when new parts started doing their thing, and all plugs were uniformly beige/light brown with no oil or other fouling.
As of today after new parts:
The car ran great for 20 - 25 minutes on local roads and highway. I let it warm up on road for 20 minutes before going past 3k and then did some higher rev stuff on a cloverleaf for a few minutes. On my return trip to home base, I pulled over to reset the clock and other things that the battery disconnect messed with. Within 60 seconds of idling at a rest stop, the CEL came back (P304) and a bit of a stumble was evident. I shut the car off and cleared the code and continued another 2 miles on the highway. At the first light after getting off the highway, the stumble returned and the CEL lit up. Car pulled fine once off idle and seemed strong and smooth. I made 2 stops before returning home and checked / cleared a P304 at each stop. Again, the car stumbled just off idle at lights, but ran strong and smooth once underway.
Looking for some guidance as to where to go next. Have read: injectors, variocam issues, dirty oil?...
Thank you in advance for any thoughts / guidance from those more experienced in the Porsche world can offer...
Update for future reference:
I installed new injectors for all 3 bank 2 cylinders and the problem persists on #4. Started up and CEL lit up after 30 seconds, but went away with light throttle to just over 1000 rpm. I cleared the code and went for a slow, easy drive around the block not allowing rpm to dip below 1000 or go above 3000. Once water temp showed 180+ I ventured slightly past 3000 a few times, but then when the engine returned to idle speed, the CEL returned.
No ticking and no apparent stumbles except at idle....Really starting to look like an intake lifter failure as suggested above.
I am hoping to accomplish lifter replacement with the engine in as I do not have a way to get the car high enough to drop the engine - parts, tools, and process research begins now!
