9 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHContinually getting P0304 code -- misfire #4 cyl.
Leading reported evidence
Replace intake lifters
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.
Leading evidence: 'Replace intake lifters' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, the most frequently mentioned possible cause is 'ecm, as he used noids' (1 discussions; 0 report identifying it and 1 suggest it). The most frequently discussed action is 'Install brand new coil in #4' (1 discussions). For that action, 0 discussions report a resolution and 1 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
The shop, Chris's German Auto Repair, in Redmond, WA, replaced two intake lifters on the #4 cylinder, and the P0304 hasn't come up since, and has run great since then.
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
They used a borescope to determine that one of the intake valves wasn't opening all the way, which points to a malfunctioning intake lifter.
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
The tech (who isn't a Porsche specialist) I've had do most of the work said he didn't think the problem was a faulty ECM, as he used noids to compare the signal to cylinder #4 and #5.
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
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.
Suspected cause · Original poster
The tech (who isn't a Porsche specialist) I've had do most of the work said he didn't think the problem was a faulty ECM, as he used noids to compare the signal to cylinder #4 and #5.
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
The shop, Chris's German Auto Repair, in Redmond, WA, replaced two intake lifters on the #4 cylinder, and the P0304 hasn't come up since, and has run great since then.
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
The tech (who isn't a Porsche specialist) I've had do most of the work said he didn't think the problem was a faulty ECM, as he used noids to compare the signal to cylinder #4 and #5.
These are separate views of the same evidence. Frequency alone does not establish a fix, and these counts must not be added together.
ecm, as he used noids
No successful repair reported for this finding.
0
Identified cause
1
Suspected cause
0
Reported fixes
Read evidence and context
Discussions that suspect a cause
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.
Suspected cause · Original poster
The tech (who isn't a Porsche specialist) I've had do most of the work said he didn't think the problem was a faulty ECM, as he used noids to compare the signal to cylinder #4 and #5.
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.
9 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Pelican Parts: 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
Looks like the problem has been solved - fingers crossed.
Car is a 2002 911 Carrera with about 88,000 miles on it.
I've had this car for two years now, and have been getting this code periodically since then, and it's also something that the PO tried to deal with.
From the records from previous owners, the coils had been changed not long ago (within about three years), as well as the spark plugs. I didn't see any record of the injectors being changed, so I've done that. Thinking that possibly a coil was faulty, I put in a new one. The plug looked reasonable, so I didn't change it.
The tech (who isn't a Porsche specialist) I've had do most of the work said he didn't think the problem was a faulty ECM, as he used noids to compare the signal to cylinder #4 and #5. Instead he thought that there might be a mechanical problem, like a bad lifter or cam.
My plan is to take it to a local mechanic who specializes in European cars, and who BTW races his own 911. In the meantime, I thought I would post here to see if anyone at this site has run into a similar problem.
Edited to add: There was no oil present in the spark plug tube when I pulled the coil and plug on #4 cylinder.
Looks like the problem has been solved - fingers crossed. As already mentioned, the cylinder 4 misfire (P0304) has been plaguing me for the two years I've owned the car, and was noted on two invoices for services for the previous owner.
After getting no joy after replacing the injectors and the coils, I took it into a shop that specializes in repairs for German cars. They used a borescope to determine that one of the intake valves wasn't opening all the way, which points to a malfunctioning intake lifter. They replaced both intake lifters on cyl. 4, and so far, the engine is back to running how it should.
The lifters aren't all that expensive, at about $150 for the pair, but the labor involved ran to 13 hours (engine was not removed).
In case you're not aware, the intake lifters on this vehicle are pretty trick, being operated hydraulically and electrically. The lifter is cylindrical, with an inner cylinder inside an outer cylindrical shell. Each intake valve is paired with three cam lobes, an inner lobe and two outer lobes. As I understand it, at low engine speeds, the inner core of the lifter rides on the inner camshaft lobe. Under higher engine loads, the inner lifter retracts into the lifter and is locked in place by a solenoid, and the lifter then rides on the two outer cam lobes, which cause higher valve lift and longer duration. The Bentley manual has pictures of the lifter and cam lobes.
Thank you for letting us know - it helps the community.
Do you have any pictures of the borescoped area to show what prompted the mechanic to conclude it was the lifter?
Nope, no pictures. The shop, Chris's German Auto Repair, in Redmond, WA, replaced two intake lifters on the #4 cylinder, and the P0304 hasn't come up since, and has run great since then.
