997 C4S MPG Issue

[caphelps]

Hi

I have a 2006MY C4S (recently purchased) and the MPG is very poor - IMO. I am getting circa 14MPG on a combined drive with a fair bit of short journeys and stop start congestion, but this still seems very poor to me. I used to have a 02 Boxster 3.2 S and for very similar motoring, (some short journeys and some commute of reasonable distance 30 miles) I averaged 24MPG. I expected the 997 to be worse but would have settled for an average above 20. Presently I can watch the fuel gauge drop just sat in traffic. ( I may be a bit paranoid but have measured the 14 MPG the manual way from fuel topped up etc.) I am also driving my car very lightly and not at all spirited whereas my Boxster did take some fun !! Dare to think what the MPG would be if I did.

Any views? Just want to know what a very average 997 of a weekly commute and some short weekend journeys normally equates to?

So do I have a problem....

I have looked at the OBD data and the Mass air flow meter seems very unresponsive. It is registering about 4 lbs/min max on a scale of about 9-90 on the app I am using. Anyone know what a normal MAF reading should be in the range of whilst driving? Then --- have I a faulty MAF causing the MPG issue..

Any help appreciated

Clive

 

[Clewsey]

ORIGINAL: caphelps

Hi

I have a 2006MY C4S (recently purchased) and the MPG is very poor - IMO. I am getting circa 14MPG on a combined drive with a fair bit of short journeys and stop start congestion, but this still seems very poor to me. I used to have a 02 Boxster 3.2 S and for very similar motoring, (some short journeys and some commute of reasonable distance 30 miles) I averaged 24MPG. I expected the 997 to be worse but would have settled for an average above 20. Presently I can watch the fuel gauge drop just sat in traffic. ( I may be a bit paranoid but have measured the 14 MPG the manual way from fuel topped up etc.) I am also driving my car very lightly and not at all spirited whereas my Boxster did take some fun !! Dare to think what the MPG would be if I did.

Any views? Just want to know what a very average 997 of a weekly commute and some short weekend journeys normally equates to?

So do I have a problem....

I have looked at the OBD data and the Mass air flow meter seems very unresponsive. It is registering about 4 lbs/min max on a scale of about 9-90 on the app I am using. Anyone know what a normal MAF reading should be in the range of whilst driving? Then --- have I a faulty MAF causing the MPG issue..

Any help appreciated

Clive

Hi Clive, that seems very low to me. Mine's a GenII granted but on a 27 mile commute to Brentford (a very slow commute) with lots of stop/start I'm averaging at least 22mpg+. Have you tried a longer run yet to see how that compares? To contrast I was getting 10mpg average whilst on-track in my old GenII S and that was pushing on. I'd say get it checked over to be on the safe side.

Simon

 

[wolfy689]

Hi

I have a 2007 C4S manual running around in town I average just under 21mpg on a run at a steady pace I have mananged 27mpg I just thought they are thirsty cars!!

Best regards

JP

 

[Lancerlot]

As one Clive to another, something is not quite right there.

Last weekend's trip to Cornbury House was a 380 mile round trip and my average was 25 mpg and that's with 530 bhp - mind you, I am a very steady driver! []

Ask your OPC for a diagnostic assessment in order to get to the bottom of it.

Good luck.

Clive.

 

[Geoff_Fields]

My previous 997S averaged 24mpg over 7 years (never reset the computer) including mix of long runs, traffic jams and track days.

 

[tscaptain]

ORIGINAL: Lancerlot
mind you, I am a very steady driver! []

Don't do that! Just nearly choked on my cornflakes........[]
I got about 24-25mpg average from my Gen 1 C2S with mixed driving. 14 does sound low - like Clive #2 I get 24ish from my Gen 2 turbo.

 

[Motorhead]

ORIGINAL: caphelps

I have looked at the OBD data and the Mass air flow meter seems very unresponsive. It is registering about 4 lbs/min max on a scale of about 9-90 on the app I am using. Anyone know what a normal MAF reading should be in the range of whilst driving? Then --- have I a faulty MAF causing the MPG issue..

Clive,

You don't mention the conditions used for measuring the MAF value but I found something on the web for a '00MY 2.7L Boxster:

Idle: 10-20 kg/min
No load, 3000 rpm: 30-60kg/min

Values measured with engine temp > 90deg C; ambient temp 20deg C; no loads switched on.

If there aren't any other obvious problems, eg an air leak, it sounds as though a trip to the PC for a diagnostic check is in order.

Jeff

 

[waxman]

Clive
until recently i was driving a 2006 gen 1 C2S manual these engines are not as efficient as the gen 2 DFI but over two years i averaged 23.1 mpg shown on the system and never saw less that 19mpg in London traffic, so it sounds like something is amiss.
tony

 

[geoff lane]

I am a very steady driver!


Yeah Right !!

 

[akwaugh]

Hi,

My lovely C4S, acquired late April, is my daily driver. I keep detailed records as probably most of us do and have an average of 23.45mpg over 7000 miles since I got it. No point in giving highs and lows as my driving is very mixed. It will be interesting to see how the winter tyres and weather in general this time of year affects mileage. Certainly the cold seems to be helping power output!

 

[Flatty]

Not that I am an expert but 14mpg sounds WRONG! I get 26-27 0n a steady run, on track I just dont look[:-]

Get a proper diagnostic check done, hopefully its just a mapping thing. However I am suprised there are no other symptoms if the MPG and fueling is so far out.

Hope you get it sorted

 

[Peter_Bull]

For last weekend's run to Cornbury House my 2007 C2 using the M55 / M6 / M42 / M6 and approx 30 miles of the A429 I averaged 28 mpg. On the run down I kept about 85 ish and a very spirited drive down the A road. Going home the traffic was not as kind but to make up time when I could I was doing more MPH than I did going down!!

I know if I keep at 70 mph then I can get about 32 mpg.

I use it as my daily commute and get about 24 mpg on a round trip of 30 miles on B and A roads.

There must be something wrong with yours

 

[tscaptain]

ORIGINAL: Peter Bull

On the run down I kept about 85 ish

Leptons..........?[]