17 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHOne cylinder miss
Leading reported evidence
Run much smoother
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
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0
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1
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Read evidence and context
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Performed · outcome unconfirmed
The others will be on their way to going bad soon and may be not firing very well as is (but not bad enough to throw a code.) After replacing all of my coils, my engine ran much smoother.
Leading evidence: 'Run much smoother' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Check light is' (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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Suggestion · Original poster
Read some other posts about persistent miss after changing coils and plugs, one was stuck lifter.
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Suggestion
The others will be on their way to going bad soon and may be not firing very well as is (but not bad enough to throw a code.) After replacing all of my coils, my engine ran much smoother.
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
The others will be on their way to going bad soon and may be not firing very well as is (but not bad enough to throw a code.) After replacing all of my coils, my engine ran much smoother.
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.
17 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
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2 acknowledgements have no verified action link; they do not establish a repair result.
Outcome without a verified action link
I had this issue a month or two ago, and cured it with new coil packs (which were overdue anyway)...
Drove the 996 two days ago. Ran fine.
Cranked up this morning, I can hear miss on passenger side. Engine check light is on.
Car has 35K miles. Not raced, driven once a week
Is this a bad coil?
It is warm enough today to put it up on stand and have a look.
Thanks for suggestions, Grant
Generic OBD-II will read the misfire code(s) you need to figure out which one is the culprit. If it's an easy-to-access coil pack, you can swap two packs and see if the misfire moves with the "bad" coil pack.
I had this issue a month or two ago, and cured it with new coil packs (which were overdue anyway)...
Did the car get wet/washed prior to today's start? Water can make a cracked coil pack act up.
Thanks dg, I was hoping maybe coil pack. Swap one to the other side and see if the miss moves banks.
Think I will use airplane engine technique to see what's cool, and try moving that coil.
Very kwel C4 you have. Agree about the 996 nay say ers.
I'm betting on a bad Coil as well. I suspect they just deteriorate over time... If one coil is bad i would replace all of them. The others will be on their way to going bad soon and may be not firing very well as is (but not bad enough to throw a code.) After replacing all of my coils, my engine ran much smoother.
Well good news and bad news. Used old method of finding misfire. Unplugged wire to coil. Middle cylinder made no difference in rpm.
Ordered three new Beru coils and new plugs. Had fun getting plugs out. Got the plug by the muffler out fairly easy using 5mm bit and 1/4 drive.
Good news: New parts came today. Had it them in two hours. Cranked up, ran fine. Then an hour to put up tools and do nice wash. Went for drive to run errand, ran fine, good power, good sound. Left parked 10 minutes.
Bad news: Cranked up, miss is back!!!
Listening, above 2000 rpm seems to smooth out. Accelerating mildly at low rpm, feel miss. Running at 3000 rpm in 4th, seems smooth. Idle is rough like 5 cylinders would be.
Read some other posts about persistent miss after changing coils and plugs, one was stuck lifter. Don't hear any metal noises. My guess is code reader is going to say "misfire," but why did the misfire come back, is the real question.
Thanks for suggestions.
Is this a convertible? I vaguely remember someone who had an issue where a cable that sent the signals to the coils as when to fire was being rubbed by some part of the Top mechanism. It was VERY hard to track down.
Thanks SFO, it is a cab. Right now I have the hardtop on. I can take it off, and look down in there. Great idea!
What is really funny, decided to drive it to office anyway. It ran perfectly, too and from the office. No miss, revs fine, good power for non-turbo
So maybe it was an injector?
Anybody use an injector cleaner? I am guessing they are not all good for Porsche injectors?
thanks,
You can try injector cleaner. I've been told the best to use is Techron. If you have not been using top tier gasoline, have been subjecting the car to short trips, you might want to run two bottles of Techron.
Whether you do just one bottle or two, use according to instructions on the bottle. As soon as the tank of fuel with the last bottle of Techron present gets down to say 1/4 tank level I like to change the oil/filter.
A bit of a long shot, but what did the harness connector of the misfiring old coil look like? I'm thinking perhaps the coil was not quite securely connected to the wiring harness and over time this caused erosion/degradation of the connector at the wiring harness which is why the misfire has returned even with a new coil.
Good idea Macster. Also OP, are you positive that all of the wires went back on with a positive "click" ? Its really easy to think a wire is on a coil correctly when in fact it is not - especially given the limited room to work down there.
This is a source reference. Confirm exact model applicability in the original material.
