5 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHHelp - Tachometer Bad? - 986 Forum - The Community for Porsche Boxster & Cayman Owners
Reported or suspected cause
instrument cluster itself
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.
Help - Tachometer Bad? - 986 Forum - The Community for Porsche Boxster & Cayman Owners
Frequently discussed work
Check intake/vacuum leaks
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
After cleaning/replacing the maf, replacing the aos (it was ok not needed), checking for vacuum leaks, cleaning the icv everything seemed ok with no check engine light.
Help - Tachometer Bad? - 986 Forum - The Community for Porsche Boxster & Cayman Owners
Read full discussion summary
Leading evidence: 'instrument cluster itself' (1 discussions report identifying this cause; no attributable repair resolution). Across 1 matching discussions, the most frequently mentioned possible cause is 'instrument cluster itself' (1 discussions; 1 report identifying it and 0 suggest it). The most frequently discussed action is 'Check intake/vacuum leaks' (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 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
After cleaning/replacing the maf, replacing the aos (it was ok not needed), checking for vacuum leaks, cleaning the icv everything seemed ok with no check engine light.
Help - Tachometer Bad? - 986 Forum - The Community for Porsche Boxster & Cayman Owners
Clean /
Suggestion or failed attempt
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 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
After cleaning/replacing the maf, replacing the aos (it was ok not needed), checking for vacuum leaks, cleaning the icv everything seemed ok with no check engine light.
Help - Tachometer Bad? - 986 Forum - The Community for Porsche Boxster & Cayman Owners
Clean icv everything seemed ok
Suggestion or failed attempt
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 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
After cleaning/replacing the maf, replacing the aos (it was ok not needed), checking for vacuum leaks, cleaning the icv everything seemed ok with no check engine light.
Help - Tachometer Bad? - 986 Forum - The Community for Porsche Boxster & Cayman Owners
Repair shop
Suggestion or failed attempt
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 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.
Help - Tachometer Bad? - 986 Forum - The Community for Porsche Boxster & Cayman Owners
Frequently discussed actions (8)
These are separate views of the same evidence. Frequency alone does not establish a fix, and these counts must not be added together.
Check intake/vacuum leaks
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
After cleaning/replacing the maf, replacing the aos (it was ok not needed), checking for vacuum leaks, cleaning the icv everything seemed ok with no check engine light.
Help - Tachometer Bad? - 986 Forum - The Community for Porsche Boxster & Cayman Owners
Clean /
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
After cleaning/replacing the maf, replacing the aos (it was ok not needed), checking for vacuum leaks, cleaning the icv everything seemed ok with no check engine light.
Help - Tachometer Bad? - 986 Forum - The Community for Porsche Boxster & Cayman Owners
Clean icv everything seemed ok
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
After cleaning/replacing the maf, replacing the aos (it was ok not needed), checking for vacuum leaks, cleaning the icv everything seemed ok with no check engine light.
Help - Tachometer Bad? - 986 Forum - The Community for Porsche Boxster & Cayman Owners
Replace aos (it was ok not needed)
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
After cleaning/replacing the maf, replacing the aos (it was ok not needed), checking for vacuum leaks, cleaning the icv everything seemed ok with no check engine light.
Help - Tachometer Bad? - 986 Forum - The Community for Porsche Boxster & Cayman Owners
Replace mass air flow sensor
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
After cleaning/replacing the maf, replacing the aos (it was ok not needed), checking for vacuum leaks, cleaning the icv everything seemed ok with no check engine light.
Help - Tachometer Bad? - 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.
5 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.
0 acknowledgements have no verified action link; they do not establish a repair result.
Generation: 20261026T061123Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
I had my 1998 986 sit in the garage for quite a while. Car has 25k on the clock.
Upon starting it up, and after temp reached 180°F, idle would sit around 1100.
Okay, I thought.. something is wrong. I take the car to the local Porsche dealer. Dealer says fuel trim levels are off and needs a new MAF. No codes no CEL. Dealer puts in a new MAF, resets all adaptations, etc, and sends me on my way; yet the car still idles at 1100. Dealer tells me that adaptations need to be set by driving about 60 miles. I take a nice 80 mile drive, car still idles around 1100. Back to the dealer.
I drop the car off at the dealer. Dealer hooks up car to their laptop, rechecks everything (fuel trim looks okay), takes off throttle body and says it's squeaky clean in there. No vacuum leaks. Dealer tells me that their computer states idle is at 850 and that engine management is working fine. Tech's ears also confirm 850.
Dealer now tells me there is nothing wrong with the car, and that the engine RPM sensor is working correctly as reported by the DME. Fault must lie in the tachometer.
Dealer tells me that nothing can be done to calibrate the tachometer. They suggest calling a VDO repair shop.
I call Palo Alto Speedometer (VDO) shop. They also tell me there is nothing that can be done to calibrate the instrument cluster. All other functions on the cluster work fine. Palo Alto Speedometer tells me to buy a used cluster (eBay?), and they'll flash my milage onto it (~$175).
Odd that the tach would be so much off. The instrument cluster has never been disassembled. With the car off, the tach needle rests in the same location as 3 other 986's that I observed at the dealership.
Any thoughts or ideas? Anyone seen this before?
Thanks..
B55er
Update:
I picked up a used instrument cluster on eBay for about $120. Supposedly it's guaranteed by a reputable VW/Audi parts dismantler. Some light scratching on the lens.
This weekend I'll put it in to test. Anyone want to take a guess that my problem is the instrument cluster and not something else?
Once verified that the problem no longer occurs with the new cluster, and it operates correctly, off it goes to Palo Alto Speedometer. They will reprogram the milage and swap the plastic lens.
B55er
Final Update:
I received the eBay replacement instrument cluster and installed it.
The replacement cluster is reporting correct RPM. Problem was with the instrument cluster itself. Really weird. Off to Palo Alto Speedometer now to have the milage changed to actual..
B55er
Wish I had found this earlier. My symptoms: car ran perfectly, would idle at 1000 to 1100 rpm. When the ignition was shut off, the tach needle would bounce for a second around 0 rpm, before stopping at the 200 rpm mark.
After cleaning/replacing the maf, replacing the aos (it was ok not needed), checking for vacuum leaks, cleaning the icv everything seemed ok with no check engine light.
Finally looks like the tach is reading 200 rpm high, explains why it did not read 0 rpm with the key off.
I need to verify this with a diagnostic tool. A lot of work, and misdiagnosis, just for a tach gauge problem.
I'm now looking for a used, good, tach.
This is a source reference. Confirm exact model applicability in the original material.
