15 captured repliesPartial discussion capture · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHwhy such bad mpg?
Leading reported evidence
Install with a k&n induction kit
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
Hi Gary, mine is a manuel and fitted with a k&n induction kit but no matter how gently i drive the most i get out of it is about 20mpg on a motorway run!
Leading evidence: 'Install with a k&n induction kit' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Clean maf (electrical cleaner' (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
I'm returning average of 26.1mpg from my 99 carrera 4 fitted with k&n induction.
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
Either clean the MAF (electrical cleaner from Maplin like Servisol IPA - isopropyl alcohol) or replace MAF.
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.
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.
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
Hi Gary, mine is a manuel and fitted with a k&n induction kit but no matter how gently i drive the most i get out of it is about 20mpg on a motorway run!
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.
15 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.
0 acknowledgements have no verified action link; they do not establish a repair result.
Generation: 20261027T044418Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
Hi guys,
I recently completed a 200 mile each way trip and doing a steady 70/75 mph in sixth gear brought me a high of 23.4 mpg. In town driving seems to return the same (23.3).
Could something be wrong? im sure it has a k & n air filter but not an induction kit, if that would make a difference. I just thought that they should give around 30 on a run. My car is a 98 c2 by the way. Also has a cargraphic exhaust and phoenix cats if that would make a difference.
thanks guys
If your MAF (air mass sensor) on air intake is damaged or contaminated (by amongst other things, K&N filter oil) the DME (engine management) will not know how much air is getting to the engine and hence will guess incorrectly how much fuel to supply.
Either clean the MAF (electrical cleaner from Maplin like Servisol IPA - isopropyl alcohol) or replace MAF.
Do not use oiled air filters.
If you use a K&N or similar oiled filter it MUST be wicked in newspaper or kitchen paper over night before fitting to remove excess oil.
+1 for the MAF being the culprit.
I know mine is a 3.6 and not a 3.4 like yours, but I did a 200-mile (each way) trip from Manchester to Norfolk last weekend at a steady 70-80mph and got 34mpg on the computer...
The 996 is actually a very slippery 0.30-0.32 (although eclipsed by the 997's 0.28, which as a current volume production car is only bettered by a few cars including the Prius!).
This means 30-35 should easily be possible at 70-80 mph cruise.
The fuel economy exibited by the car is fairly insensitive to air speed based losses cruising at "normal" speeds. ie 30-100 mph.
Pretty impressive for a semi-supercar.
Either 3.4 or 3.6 is quite small capacity compared to other "sports" cars or half the stuff coming out of MB or BMW. Even the lowly VW R32, is erm 3.2!
No substitute for cubic inches indeed!
mpg
I'm returning average of 26.1mpg from my 99 carrera 4 fitted with k&n induction.
However since fitting the k&n, some 4000 miles ago, this figure has NEVER changed no-matter how hard I drive or how frugal I drive !
How often is the computer supposed to recalculate the mpg figures ?
I'm I also suffering dirty maf ?
Mine's a tip, but overall running average is about 26 on the trip page of PCM, which I have not reset in over a year. I see around 30 on long motorway runs, and low 20s if I'm in traffic. I'd have to say when I bought it I was prepared for worse than that.
Mind you I do drive it like an old woman most of the time..
My 2005 C4S Cab Tip seems to be returning around 23mpg on average with a majority of M4 50mph action(why do they favour the 50mph average speed cams now???) plus some short sprints on the country road at either end.
I have only had the car for a few weeks and I assumed this was normal.
I seem to get just under 300miles per tank doing this.
Not sure on the tank size.
The car is going back to OPC for MoT, AirCon refill and PCM investigation.
If y'all think this is bad mpg then I will get them to investigate this under warranty... :?:
Hi Gary, mine is a manuel and fitted with a k&n induction kit but no matter how gently i drive the most i get out of it is about 20mpg on a motorway run!
OK, to clarify, the 30+ mpg are STEADY CRUISING figures on the flat no braking/accelerating etc.
If you drive round town, race the Nurburgring or even just check your tank average you won't get 30+ (unless you have one of those diesel 911s or you drive Miss Daisy).
Ref: the OBC - the avg mpg is calculated until you reset it (pull stalk for 2+ secs) or until you have a power outage (battery disconnect etc).
However, if all the above you still get crap mpg on a run do this:
Remove MAF (you need a security Torx screwdriver T20 to do it).
Spray IPA into the two openings (one is in the other out, do both). Shake a bit and repeat until you are confident the crud is removed.
Don't let the IPA evaporate and leave the disolved crud as residue - you must shake the IPA out.
Replace into bracket and screw up T20s.
WHAT'S IN A MAF?
DO NOT INSERT ANYTHING INTO THE APERTURES!
If you break the hot-wire (film), you buy a new MAF.
Mine does about the same, getting 22mpg [19-20 if I give it some pedal]
on a mix of roads at the moment and just under 300miles per tank.
However I did a calculation with mileage and fuel and came out at 24-25
so the OBC may on the low side.
TB
This is a source reference. Confirm exact model applicability in the original material.
