Evening all

This isn't another moan at the impreza's average fuel consumption, but ive noticed a bit of difference in my cars usage.
Basically, I was getting ~200 miles to a tank, but this has dropped to about 150.
Im just worried that something may be wrong, where should I start looking?
Car is remapped with decat, fuel pump and panel filter.
I'd appreciate any advice!

 

Dont press the pedal so hard lol

colder weather effects consumpsion but many things can cause it to use more, dirty airfilter, lambda sensor on its way out, blowing exhaust. any fuel smells?

 

Haha, my driving style hasnt changed, Air filter looks good, Exhaust has recently been wrapped and checked over.
Whats this about lambda sensor, im guessing that helps with fuelling?

 

Don,t panic, although 150 miles to a tank full does seem a bit excessive, the weather does make quite a difference. I reckon my fuel range drops from 220 miles per tank down to 200 when the temperature drops from summer to winter. I,ve got a 2.5 hawkeye wagon which has had a custom map from Silverstone Autosport.Also, short runs kill my consumption, whereas on a run, i can get 30mpg if i,m really careful.

 

If all you've done is decat and remap with a panel filter and fuel pump I'd be livid if my fuel consumption was 150 to a tank!

I run a 20g on mine @ 380bhp and even if I drive it with the loud pedal firmly pressed to the floor everywhere, it'll still do in the region of 180 on a full tank, so 150 on a standard engine and setup points to something being very wrong.
Take it to a specialist, it could be any number of things, and without seeing the car, it'll just be guesswork on here.

If your mapper is close by suggest they're your first point of call as they can check your fuelling.

 

Ok, i'll contact him.
It hasnt always been like this since the remap, although I havent driven it much in the last 2 months and when I have, they've been shorter journeys. Don't know if thats worth considering.
edit: around 14-15mpg.

 

I had a similar problem found out had a hole in the fuel filler pipe causing the fuel to evaporate. Can u smell fuel???

 

I only get 80 miles every week from 23 litres (5 gallons) of V-power, (£33) that's covering 3.2 miles one way every day.
6.4 miles round trip per day, plus weekend driving. that's on a newage 2005 WRX Custom mapped, headers & Up-Pipe ported, all decatted, headers DEI wrapped, turbo blanket, 3 port boost, Walbro pump, I would be lucky to get anymore than 80 miles on these daily short trips. I have yet to get it on rolling road, mappers indication is 290bhp ish ?

 

Hi,im running the same bhp as you my mpg was good i thought for my bugeye wrx i don't thrash it then after my last map tweak it started to act strangely some days it was like i'd lost 50hp then the next ran great & so on,but think ive got to the bottom of it dodgy o2 sensor as at first i didnt have any cel's coming on then week or so ago got 0031 front o2,maybe its a possibility for yours.

 

the sensor that has gone on my car is the rear one, brings up code P0037, HO2S Heater Control Circuit Low (Bank 1 Sensor 2). this is the rearmost sensor in the short cat pipe just before the exhaust center section.
but the rear O2 sensor has absolutely nothing to do with fueling, it's only mission in life is to check weather your Catalysts are working correctly & the car is running as "green" as it should be.
It's the front (pre cat) sensor that trims the fueling requirements. that I had replaced not long ago, with genuine Denso.

 

First of all, on the standard TD04 turbo, you won't see more (give or take 1-2bhp) than 280bhp. Your spec would indicate your turbo is the limiting factor in that regard.

Secondly, with that spec you'd easily manage 220-240 on a tank with normal driving even in a built up areas, BUT if you're doing 3 mile journeys the car isn't even getting a chance to warm up properly so that's probably why you're seeing those figures.
Tbh 23 litres isn't even half a tank. I normally say that as lon as you're getting in the region of 100-120 on a half tank that's standard unless you drive like a grandma

 

Ive had a thought and realised that my fuel level was probably a bit lower than i normally let it. Im getting similar figures usually to wrx_2005.
Im going to keep my eye on it.

One last thing, the knackered sensors didnt throw up any lights, but there were codes?

 

Noticed my 05 wrx ppp has dropped from 220 to 150 from full to quarter tank over the last month or so. Might be because i fitted Brembo's with CL pads meaning im still accelerating harder and braking much, much later.

 

I fitted 8 pot K-Sport 330's - my fuel consumption didn't drop but my braking distance did

 

Knackered O2 sensors will throw a CEL eventually - mine did on my old WRX.

 

Anyway of checking them before hand? I think im bing paranoid but obviously I want to know the cars running at its best!

 

Just go see your mapper mate. This could be 101 things and any decent chap will help you out without charging you the earth!

 

Will do. Its due for a service anyway so i was going to get them to chuck a sensor on.

 

replaced the one on my 2000 turbo. fuel consmption dropped from 15 mpg to about 25-28 so well wdrth trying. didnt buy a new one as did it as an experiment but now its proven i feel more justified spending £100 on one

 

Thats what im thinking/hoping. No weird smels, but on start up it stinks of burnt fuel at the exhaust.