ade_sti

iTrader: (2)

Hi all,

My 2003 Sti has no fault codes or engine lights but the economy is really bad.

Could it be the MAF, Oxygen sensor or both? (Before I waste my money replacing both!!!)

The car also has slight hesitation below 3000 rpm.

Regards

Ade

NOSSY_89

If you could do some data logging that would be good, AFR etc.

When was it last serviced, air filter and plugs.

ade_sti

iTrader: (2)

Plugs changed only a few thousand miles ago. Air filter new.

ade_sti

iTrader: (2)

I have dash command- would that be suitable to log the data I need?

stockcar

exhaust blow, air leaks, etc will all have an affect..........

when you say poor in what way?? how good was it before??

lockheed

iTrader: (1)

tyres at correct pressure i presume ? , that can affect fuel consumption .

Vxr2010

possibly coolant temp sensor , thinks the cars not warmed up and therefore over fueling , and could account for not good running below 3 k as it thinks it’s still warming up , o2 normally throws a code , maf won’t throw codes , try and clean the maf see if it helps , as above what do you class as poor mpg , try disconnecting the battery , leave the battery off over night then connect it up and see how it drives the next day , some data would help 👍😁

ade_sti

iTrader: (2)

Getting about 15 -16 mpg - normally would get around 20ish (mainly B roads and town)

Flat4x4-again

iTrader: (1)

That's pretty crap. If there is nothing obviously 'wrong' as people have suggested, I had a Terraclean done on my Classic a few years ago which could get some of the carb build-up out.

Vxr2010

i would do a full tank to empty ish v miles and see what it’s doing , you may have just been a bit more spirited driving it , still worth getting it plugged in if some one is near you , just for peace of mind 👍

stamina_daddy

iTrader: (3)

Obviously taken into account the cost of fuel.
I've never gauged by miles per gallon but how many miles I get out of say 50 quid.
Reset trip meter each time.
when 99ron was 2 quid a litre it was costing me nearly 50p a mile.
Got 70 miles from 30 quids worth.

Vxr2010

try what i have said above as it’s more accurate way to do things and may account for your mpg issues , is yours highly tuned as mpg will be crap any way 👍😁

ade_sti

iTrader: (2)

The car is a PPP with Ecutek map. I am going to clean the MAF and see if that helps. Running about 330-340 so nothing out of the ordinary.

I live in Spain now (near Sevilla) and most garages have no idea what to do with my car when I drive in! They have never seen or worked on one before. To be honest they don’t want to touch it!

See if the MAF clean does anything. Car hits boost, no issues. So if it is not the MAF then I have no idea. I will fill the tank full and see how many miles I get this week!

Thanks for the advice

Flat4x4-again

iTrader: (1)

Well, I guess you will have had the air con on to the max recently ?

That's gotta be worth 10% on your fuel consumption...

ade_sti

iTrader: (2)

Just in case others have had the same issue. Cleaned the MAF and the boost solenoid the other day.

Boost solenoid was quite clean. The MAF was really dirty. Reset the ECU and cleared any codes. The car is now very smooth off boost and comes on boost much stronger. Also holds boost much better with a 0.1 bar increase. Ran a bit strange for a couple of days due to the MAF being removed and replaced and ECU reset.

Also the MPG seems to be much better. Too early to calculate the exact MPG but is clearly using less fuel as I have done significant more mile on the same segment on the gauge as normal.

Thank you all for the advice. And yes the air con has been on full every day!!

marcomurabia

thinks the cars not warmed up and therefore over fueling , and could account for not good running below 3 k as it thinks it’s still warming up , o2 normally throws a code , maf won’t throw codes

ade_sti

iTrader: (2)

Cheers - I will check coolant sensor also.