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THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHDrop in gas mileage - unknown cause - 986 Forum - The Community for Porsche Boxster & Cayman Owners
Leading reported evidence
Replace after an ims bearing failure at ~40k miles (need
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
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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
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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
The car has 77K miles on the body, but the engine was factory-replaced after an IMS bearing failure at ~40K miles (need to look up exact amount).
Drop in gas mileage - unknown cause - 986 Forum - The Community for Porsche Boxster & Cayman Owners
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Leading evidence: 'Replace after an ims bearing failure at ~40k miles (need' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Replace after an ims bearing failure at ~40k miles (need' (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
I changed the air filter six months ago, but haven't swapped spark plugs.
Drop in gas mileage - unknown cause - 986 Forum - The Community for Porsche Boxster & Cayman Owners
Replace air filter, spark plugs, etc
Suggestion or failed attempt
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
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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
When was last time you replaced your air filter, spark plugs, etc..?
Drop in gas mileage - unknown cause - 986 Forum - The Community for Porsche Boxster & Cayman Owners
Replace spark plugs
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 · Original poster
What is the cost and procedure (time to do at home) of changing spark plugs?
Drop in gas mileage - unknown cause - 986 Forum - The Community for Porsche Boxster & Cayman Owners
Use durametric
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
No it didn't - the only way I found it was by using the Durametric.
Drop in gas mileage - unknown cause - 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.
8 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.
Outcome without a verified action link
Replaced and performance + fuel economy back to normal.
Hey all, my 2002 Boxster S has been running at lower efficiency, and seemingly lower power, for a few weeks, and I'm now getting around to chasing down the source of the problem. I noticed that my mileage used to be around 20-23 mpg in the city (27-29 highway) but it has since dropped to around 15 mpg. In addition, there seems to be a slight drop in power as well as a faint unburnt fuel smell coming from the exhaust. There is no check engine light.
Any ideas on how I can chase down this issue? Has anyone had this happen before?
Note that my car did get hit at low speed in the front end a few days ago, but I think that this is independent because the issue popped up weeks ago.
Thanks for your help!
Tufts
When was last time you replaced your air filter, spark plugs, etc..?
Usually when you neglect these, the mileage and the performance goes down pretty quick, hopefully is something this easy
Thanks for the tip. I changed the air filter six months ago, but haven't swapped spark plugs. The car has 77K miles on the body, but the engine was factory-replaced after an IMS bearing failure at ~40K miles (need to look up exact amount).
What is the cost and procedure (time to do at home) of changing spark plugs?
About 2 hours to replace plugs - cost is minimal as the Bosch or Beru plugs are standard items. You need to jack up the rear of the car install jackstands and remove part of the wheel arch plastic liner + moulding for access to the coil packs and plugs.
A few years ago I had the same symptoms as you, plugged in the trusty Durametric and found the MAF below limits. Replaced and performance + fuel economy back to normal.
No it didn't - the only way I found it was by using the Durametric.
The performance had fallen off slightly so I plugged it into the diagnostic port. The big difference was with the new MAF - everything was better (economy + low / mid range performance) it felt like a different car. Who'd have thought......
Thanks for the tip! I cleaned out the MAF using standard MAF cleaner spray and the car is like new. Improved gas mileage and throttle response. Possibly a bit quicker too.
