7 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCH996 Misfire nightmare
Reported or suspected cause
mass air flow sensor
Reported cause
No successful repair reported for this finding.
1
Identified cause
0
Suspected cause
0
Reported fixes
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 report identifying 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.
Leading evidence: 'mass air flow sensor' (1 discussions report identifying this cause; no attributable repair resolution). Across 1 matching discussions, the most frequently mentioned possible cause is 'mass air flow sensor' (1 discussions; 1 report identifying it and 0 suggest it). The most frequently discussed action is 'Clean with the guys who' (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
So I think the car must have been remapped and when I disconnected the battery it's return to factory settings and is awaiting a responce from the post cat sensors.
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
Took the switch out and reconnected the battery again but it was no better.
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 read in the user manual that after the battery is reconnected the engine will take a little time to reset it's values, so when it ran a little funny I thought it was okay.
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
Ruled out plugs and coils as they have all been changed recently.
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
So I think the car must have been remapped and when I disconnected the battery it's return to factory settings and is awaiting a responce from the post cat sensors.
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 read in the user manual that after the battery is reconnected the engine will take a little time to reset it's values, so when it ran a little funny I thought it was okay.
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 read in the user manual that after the battery is reconnected the engine will take a little time to reset it's values, so when it ran a little funny I thought it was okay.
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.
911uk: 1 discussions
0 evidence records excluded for query context · 0 excluded by outcome qualification · 0 adjusted by outcome qualification.
3 acknowledgements have no verified action link; they do not establish a repair result.
Hello,
After some help and advice if possible.
I've had my 1999 996 for around six months now (my first Porsche) and I have a misfire problem. It started about 2 months ago; I took it to the garage to be checked out - misfire on 4, 5 and 6 was the reading. They tested it and couldn't get it to misfire so reset the CEL and told me to come back if it persists.
The CEL light came on a couple of weeks later so I decided (after reading the forums) to replace the plugs and coilpacks. Success; no problems for the next 6 weeks until - and I find it difficult to admit this - I decided to fit the switch on the dash that allow you to put the tail up and down.
I removed the battery contacts to do this, installed it no problem. Tested it and it worked fine. I read in the user manual that after the battery is reconnected the engine will take a little time to reset it's values, so when it ran a little funny I thought it was okay.
Unfortunately the CEL came on and the engine sounded terrible. Took the switch out and reconnected the battery again but it was no better. The fault codes I now have are P0300, P0304, P0305 and P0306.
Any ideas? It's still sounding awful, revs are low at idle, around 500rpm. When I give it some throttle it drops a little then trys to pick up but struggles. Thanks for reading,
Dave in Manchester
PS this hasn't made a dint in my love for the car, still planning lots of trips as most of the time it's a joy to drive. Gonna drive to Beirut in Spring!
Thought about this one over the weekend;
Ruled out MAF sensor as this would effect both banks.
Ruled out plugs and coils as they have all been changed recently.
That left oxygen sensors. Figured I could try swapping them from one side to the other and then if I get misfiring on 1,2 and 3 I'll know they're faulty.
Went out to have a look where they are and how easily they'll be to replace and found the problem. Both post cat sensors have been cut, they're not wired to anything. So I think the car must have been remapped and when I disconnected the battery it's return to factory settings and is awaiting a responce from the post cat sensors.
Not sure what to do now? I'm guessing the cat is probably gone or why else would somebody do this? Any ideas?
Dave
Connect them back up (if you can) and see what fault codes you get then.
Disconnecting the battery would not affect the fuel map - it will just reset the adaption values.
If both O2 sensors were cut, it would not affect just one bank. From the codes you were getting, it could well be a dodgy Variocam solenoid.
Hi Richard,
Thanks for taking the time.
Yeah, failure on only one bank does suggest it's nothing to do with the O2 sensor - since they're cut on each side. Still a strange discovery.
I've got it booked into the garage next tuesday so all will be revealed. Hopefully something quick and cheap - ever the optimist!
Regards,
Daev
Got my car back today!
Turned out to be the MAF. Not sure why it was only misfiring on one bank but just thrilled to have it fixed. The garage suggested that the reason two of the O2 sensors where cut is becuase 1999 models only have two sensors (not four) and the exhaust must be from a later model. Is this right?
Overall cost was £220, new bosch part + half an hours labour.
Thanks to all that helped.
Dave
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