20 captured repliesPartial discussion capture · Source accounts, not a confirmed diagnosis
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Discussion summary
YOUR RESEARCHRough idle/no rev problem - 986 Forum - The Community for Porsche Boxster & Cayman Owners
Leading reported evidence
Check vacuum hoses
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 have checked the vacuum lines on the drivers side that goes to the fuel regulator.
Rough idle/no rev problem - 986 Forum - The Community for Porsche Boxster & Cayman Owners
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Leading evidence: 'Check vacuum hoses' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, the most frequently mentioned possible cause is 'intake/vacuum leaks' (1 discussions; 0 report identifying it and 1 suggest it). The most frequently discussed action is 'Check cap and the fill tube' (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.
Rough idle/no rev problem - 986 Forum - The Community for Porsche Boxster & Cayman Owners
Replace when
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 can see no leaks and fuel pressure changed when disconnecting the vacuum line.
Rough idle/no rev problem - 986 Forum - The Community for Porsche Boxster & Cayman Owners
Run like
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
Mine ran like that when I left the oil fill cap off.
Rough idle/no rev problem - 986 Forum - The Community for Porsche Boxster & Cayman Owners
intake/vacuum leaks
Suggestion or failed attempt
No successful repair reported for this finding.
0
Identified cause
1
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 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
This is the best way to check for vacuum leaks...with only being able to run for 15 seconds, it isn't a small leak or a pinhole issue if it is caused by a vacuum leak.
Rough idle/no rev problem - 986 Forum - The Community for Porsche Boxster & Cayman Owners
Check vacuum leaks...with only being able
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
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
This is the best way to check for vacuum leaks...with only being able to run for 15 seconds, it isn't a small leak or a pinhole issue if it is caused by a vacuum leak.
Rough idle/no rev problem - 986 Forum - The Community for Porsche Boxster & Cayman Owners
Reported and suspected causes (1)
These are separate views of the same evidence. Frequency alone does not establish a fix, and these counts must not be added together.
intake/vacuum leaks
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
This is the best way to check for vacuum leaks...with only being able to run for 15 seconds, it isn't a small leak or a pinhole issue if it is caused by a vacuum leak.
Rough idle/no rev problem - 986 Forum - The Community for Porsche Boxster & Cayman Owners
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.
20 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
986Forum: 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.
I'm going to move this problem to the technical forum. I have a '98 Boxster Base with a rough idle/no rev problem. The battery and plugs are new. The coil packs ohm out. The fuel pump and fuel filter are new. Fuel pressure is rock solid. The vacuum looks to be good. Oil has been changed as well. Could a stuck fuel injector or injectors cause the rough idle and inability to rev about 300 rpm?
I second the maf. If you disconnect the maf sensor the engine should then run in open loop. If it runs better it is a sure sign the maf is bad. Sometimes cleaning them helps but not always and be sure to use a cleaner spray designed for maf cleaning
Disconnecting the MAF made no difference. I am definitely missing on cylinders. Trying to get access to ohm out the injectors. From underneath it's tricky. May have to remove the secondary air pump on the passenger side and the air box on the drivers side to get full access to the injectors and rail.
Does anyone know the proper resistance for the injectors? I got to one and measured 12.2 ohms. I also measured the voltage at the injector connector to be 12 volts with just the key on.
Have you checked for vacuum leaks? I had this happen after doing some work on the intake. Put it back together and couldn't see it from the top, but I had created a vacuum leak when I put it back together wrong. No codes because it wouldn't stay running. If you aren't getting any codes I highly doubt it's anything related to your injectors.
Thanks for the replies. I would really like to learn a way to check this vehicle for vacuum leaks. I have checked the vacuum lines on the drivers side that goes to the fuel regulator. I can see no leaks and fuel pressure changed when disconnecting the vacuum line. On the passenger side, I have traced from the intake manifold all the way to the vacuum canister and the four way tee. I can't see any damage to the lines so far. And I can't really do much other than visual inspection. Pin hole leaks would be almost impossible to detect visually. And I can only keep the car running about 15 seconds, so chasing a leak with something like carb cleaner won't work. Keeping it running long enough to troubleshoot is a problem. I'll post a video of it running to give you all a better idea of what I am seeing and hearing. I do appreciate all of your help.
You can rent a smoke machine, make your own, or get it to a mechanic to figure out. This is the best way to check for vacuum leaks...with only being able to run for 15 seconds, it isn't a small leak or a pinhole issue if it is caused by a vacuum leak.
When was the last time the car ran right? What have you done to it that may require you to check your work? If you retrace those steps you may find the answer.
I haven't heard of these things having much of an issue with injectors. I'd look into a smoke machine to get that at least eliminated as a cause. After that I'm not sure where to lead you with no codes being posted.
Brake boost vacuum line? That's the biggest one and I'd think most likely to completely stall the engine. It mounts to the front left or right rear intake manifold and the opposing one should be covered/blocked.
Last two posts are good examples of why I'm saying try and track down a vacuum leak. The car will tolerate them for a bit but when they become too large it can no longer compensate and it shuts down.
Thank you all again for advice. I'm going to do some disassembly tomorrow and track down that leak. Took the day off and went down to Tubac, AZ (a small artists colony). Bought a couple of pots for my wife and had a great Mexican meal with my wife (the margaritas are hampering car repair). The goal is to have the car running by my 33rd anniversary at Memorial Day and drive it to San Diego.
