13mpg??

[ian_jemo]

Hi all

My car is running at an average of about 13 MPG and this is with me driving it normally.

Does anyone know what can cause this overfuelling. Is there anything I should check or change.

Thanks

Ian

[BrianSmith_S2]

Hi all

My car is running at an average of about 13 MPG and this is with me driving it normally.

Does anyone know what can cause this overfuelling. Is there anything I should check or change.

Thanks

Ian

what about your lambda probe?? its been recommended to change this every 60K or so to maximise mpg and performance.

my experience of mpg is as follows.

driven very hard, castle combe track day, etc ....9ish mpg
hard road driving........................................... 14ish mpg
commuting/urban..........................................19i sh mpg
commuting......................................... ..........22ish mpg
longer motorway runs at about legal speeds.......28ish mpg
long motorway runs well within legal speeds......+30mpg

(my record is 34.4 on 20ish mile stint from louth to lincoln the other week. no jams and kept her to 55ish all the way)

i find the biggest killer of mpg is when your into stop start traffic jams, or get into a race with another car that doesnt realise your a wolf in sheeps clothing.

[ian_jemo]

lambda probe was changed about 1 month ago, I used a universal one this wouldn't make a difference would it.

[BrianSmith_S2]

not too sure on tha, but it could be the problem. what mpg were u getting before you changed it??

[ian_jemo]

i'm sure it was even less about 12mpg so it did improve but obviously not by alot.

What about the MAF could this affect MPG

[BrianSmith_S2]

i'm sure it was even less about 12mpg so it did improve but obviously not by alot.

What about the MAF could this affect MPG

very quick and easy to check/clean (mafbaf ) the maf. im sure it can effect the mpg, but normally shows up with rough running of the engine if dirty. not sure what happens if it develops a fault thou.

best for other experts on the forum to add there advice on this one i think.

[Nuvo]

i'm sure it was even less about 12mpg so it did improve but obviously not by alot.

What about the MAF could this affect MPG

Based on what you describe here I would posit that the lambda sensor is not the cause of your poor economy. Try searching the forum as I'm sure you'll find the answer(s) you're looking for.

[murat]

it could be a boost leak, it causes rich running

[nip]

lol mine does about 60 milles for 20 pounds and thats not going fast all the time, is that good or bad

[dan_b]

Dodgy lambda, boost leaks, a stuck ISV and filthy MAF can all cause over-fuelling.

[ian_jemo]

Cheers mate I'll have a check.

Where ISV I presume its the metal thingie towards the back of the engine. Off of the T piece hose. If it is sticky how can it be fixed??

[dan_b]

Correct - it's a metal thingie with a tube sticking out of it which plugs in to the metal hose that brings air in to the throttle body from the intercooler...

You can remove it and give it a thorough blast with WD40 to clean it out.
Boost leaks make a difference too - before I did my SAMCOs my car was running rich and seeing about 16mpg, now I've fixed all the leaks it's back to the mid-20s again.

[S2central.net]

Only other thing to suggest checking here is the coolant temp sender - not the one for the guage... There is one at rear of cylinder head used by ECU only to determine water temp. If the ECU thinks the engine is cold then it runs rich.

PAul

[Tommy200rs]

Check first the ECU error codes with VAGCOM. Noting else before that. Then the leak test and after that faulty sensor hunting.

[S2 PTH]

I'd say it is boost leakage causing your over fueling. I fitted a DV (just to see what it was like) and my car smelled to be running very rich. Plus i burned 1/4 of a tank in 5miles lol So, I'd say boost leakage caused it mate! (which i supose with overfueling could destroy your cat and hence mess up your lambda sensor!