I have a fuelling problem I think


Just done tour of Derbyshire and I used a full tank of optimax with booser (millers) its only 100 miles ish !!!!

The car is


95 wrx,
80000 mls
hks mushroom filter with air resonator removed and cold air duct from front bumper
full decat exhaust firestorm back box
grahame goode double piston dump valve (vta I think)
delimited via unlock chip not a performance chip
new maf and lamba sensors
I have a auto meter afr gauge which always reads rich when ever on throttle, hard or soft,
On idle it reads lean/stoich running through whole ranges or is completely blank

I have also done earthing mod but had problem before this,

The temp (water) never seems to alter much ie half way up gauge pretty steady no matter how hard its driven

Oil used is castrol rs as recommended on numerous oil treads, cant remember ratio though off hand, car has slight piston slap.

Get a fuel smell from exhaust sometimes
Any ideas before i take it to garage?
Would a fuelling cpu resolve the matter thought about up rating the coil packs to bosch ones, any opinions?
Fishing for causes and remedies really, but aint everyone.

 

I'd of thought the area you have been driving in does have quite a few "gradients", so perhaps you have used the fuel going up these.
Sorry, but its a hard question to realistically answer,could be a "MAF" sensor fault, running it over rich.

 

I'd be very suspicous of a dodgy lambda - new or not!
Remember that if the lambda's dodgy, it'll look right most of the time as you & the car are both looking at the same lights so it'll only be 'readable' at WOT, which should read slightly leaner than usual if there's a problem. It might not be heating up properly or something?
Can't think of anything else - leads & whatnot shouldn't come into it, as it's simply pumping in too much fuel!
How's the performance? Same as usual? If it is, the you may have a problem with stoich (again, don't bother reading the lambda!) so boost won't be affected.
I think I've waffled enough now

 

thanks guys will try another lambda, any other thoughts?

 

Maniac,

you were following us in my 93 WRX, and guess what? - we used around 40 litres too!! I think the route total was 140-odd miles, so not too bad really......although I'm not sure if you were using full throttle all the time?

 

so your saying thats how it is ?

if so cool nowt to worry about, just it dont feel quite right if you know what i mean

morgan

 

Don't forget that when we wern't stuck behind traffic we were hitting the gas quite hard in 3rd & 4th.

WRX's have fairly low gear ratios (which won't help mpg), and with better breathing (induction & exhaust) you car has the opportunity to burn more fuel.
It's not unusual to get into high teens mpg-wise on a hard drive - just that normally you won't be pushing that hard for that long, so you won't notice the change in mpg over the course of a tank.

The fuel smell from your exhaust is probably caused by the exotic mix of Optimax + booster - nothing to worry about. This will be more noticeable after a cold start when the engine over-fuels slightly.

Was nice to meet you on Sunday - hope you enjoyed the drive!!

 

yep i enjoyed the drive good tomeet you lot too, let me know when your next out i might tag along if im allowed

morgan