1 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHPls help diagnose cold start stalling and misfire - '99 996 3.4 tip
Leading reported evidence
Check coilpack connections ok
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.
Pls help diagnose cold start stalling and misfire - '99 996 3.4 tip
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Leading evidence: 'Check coilpack connections ok' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Check coilpack connections ok' (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
- Checked fuel system - connected a hose to the return fuel line, jumpe the fuel pump and got exactly 850ml in 30 seconds, all good.
Pls help diagnose cold start stalling and misfire - '99 996 3.4 tip
Clean cycled
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
- Cleaned throttle body, removed IACV and thoroughly cleaned, cycled with a 9V battery, reinstalled.
Pls help diagnose cold start stalling and misfire - '99 996 3.4 tip
Clean ports in/out of iacv too
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.
Pls help diagnose cold start stalling and misfire - '99 996 3.4 tip
Clean throttle body, removed iacv and thoroughly
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
- Cleaned throttle body, removed IACV and thoroughly cleaned, cycled with a 9V battery, reinstalled.
Pls help diagnose cold start stalling and misfire - '99 996 3.4 tip
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.
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
Tried clearing codes and restarting with/without MAF connected, no change.
So I'm sure there's plenty smarter people on rennlist than me who can offer advice on fixing my 996! It's a bit of a saga so thanks in advance. Have been reading all threads remotely connected to 911 stalling issues for the last month already. This is for my 1999 996 C2 tip cabriolet, cable throttle RHD (Australia). Driving home a few weeks back, roof off, everything is fine. Cruising at about 60km/h, then I hear the engine stumbling and sounding rough, audible misfiring. I'm almost home, pull to a stop to turn into my street and the engine dies. Restarting it was a bit difficult, managed to limp into my garage. Also trying to keep track of troubleshooting on my blog dtmtune.com.
Pull codes;
P0341 - Camshaft Position Sensor 1 - Signal Implausible, Short to Ground, Short to B+ (that said, this code has been coming up for the last 3 years
)
p0300 Misfire Damaging to Catalytic Converter
p0306 Misfire, Cylinder 6, Damaging to Catalytic Converter
So, initial round of wild *** wrenching begins. Right now I'm thinking it['s just a bad coilpack/plug on cylinder 6.
- Drop oil and check filter - some tiny orange sealant bits, but no metal. Refilled mobil1 5-50
- Put in a 997 oil pressure piston and spring which I was planning to do anyway
- Removed MAF and cleaned with CRC spray. Removed airbox, checked there was no dead animals blocking the air filter, reinstalled.
- Cleaned throttle body, removed IACV and thoroughly cleaned, cycled with a 9V battery, reinstalled. Cleaned ports in/out of IACV too. Looked for any obvious loose hose clamps etc downstream of the MAF.
- Replaced spark plug tube, spark plug and coilpack to cylinder 6
- Bypassed fuel pump relay with a fused wire, fuel pump audibly runs OK.
Restarted car - started OK, but again very rough idle - low and lumpy, misfiring audible within seconds. Engine would keep turning over with foot on throttle up to about 1000rpm, without any throttle idles very low and then dies. Now reading codes for misfires, and specifically misfires on cylinder 6... and now 5 as well! Tried clearing codes and restarting with/without MAF connected, no change. Triple checked coilpack connections OK.
Next round of random actions focussing on fuel system.
- Checked fuel system - connected a hose to the return fuel line, jumpe the fuel pump and got exactly 850ml in 30 seconds, all good.
- Replaced fuel pressure regulator with a new Bosch 3.8bar as it's a cheap part. Old regulator had some fuel dripping out the vacuum port so not in good shape anyway.
- Connected a fuel pressure gauge to the test port. I get 3.8bar with key in, engine off, drops to 3.2bar with key out.
- Started engine - again, very rough and low idle, however pressure good at 3.8bar. when the engine eventually died after 15-20 seconds the fuel pressure drops immediately to zero instead of holding.
This is the video of the last test run -
You Tube
Hoping for the collective megabrain of rennlist to be able to come up with some help on what to look at next! I've had some thoughts but I'm no expert
What about the P0341 code I've been ignoring? [code has been there for 3 years and i've managed to successfully ignore it this long! But... could be a variocam error?]
Maybe there's a big vacuum leak somewhere? [Would that cause the initial problem where I'm driving at a set speed with no issues, then out of the blue a big misfire?]
Crankshaft position sensor? [Car does start OK, but won't keep running. plus I replaced the CPS a couple years ago]
Compression test? [.... haven't got a compression tester, yet...]
Any suggestions on what to do next, or if I've overlooked something much appreciated.
This is a source reference. Confirm exact model applicability in the original material.
