[Mk2] [NA] really poor fuel economy

[wes]

rev4 na fitted mongoose exhaust and apexi induction kit
the cars been serviced regulary. fuel filter canged. use vpower
just to get that out the way.
put 35 quid of vpower in (33.05 litres) 1 bar from full a couple of days ago done about 165 miles now only 2 bars sbove a quarter. used to get about 320 miles per tank. no vault light on dash and no smell of a leak.
is reading the fault codes gonna help
any thoughts please

[fearless]

ive read on here about oxygen sensors affecting fuel economy think thay are about £70 to buy . mine is the same not that good on petrol either i have no leaks either and apexi filter standard exhaust which is blowing a little which wont help i suppose. but my right foot is a little heavy sometimes which probably may be my problem but a very enjoyable drive into work though. also scared the wife yesterday managed to get 80mph down a slip road to join the A13 she was not impressed nevermind

[wes]

ive driven the same all the time ive had it. its not down to my right foot. same journey everyweek.
realised it been getting worse over a time thats why stuck the mods on now really crappy mileage

[mrfil13]

Lambda sensor is a likely suspect, also if you have had the cambelt done recently the timing could be out. If its retarded it can reduce your mpg.

[Olly P]

Although that works out as 22mpg, which is still better than most of our tubby owners have to put up with

[screech205]

Something definitely a miss there mate, i get about 230 miles to £35 of V Power so would expect n/as to do a lot better than that!

Likely suspect is the lambda sensor, seen it quite a few times on here

[Si_Crewe]

Bit random this but I thought I'd mention it...

It's possible you don't have a problem with your engine at all but, instead, it could be your tank sender.

Have you physically stuck £40 of petrol in, run the car until it got to 1/4 of a tank then stuck another £40 of petrol in?

I used to have a Chavalier that'd do this.
The indicator would gallop down from full to half really quickly and, on long journeys, I'd think "bu88er, I'd better fill up again before I go any further!" and, when I tried to put petrol in, I'd only get about 5 quids-worth in it.

[mrfil13]

Tubby owners how heavy are your feet, the lowest ive had in my turbo so far is 26mpg, got 38 mpg on the way back from london up the m1 My N/A used to get around 28-30 mpg.

Or have you got to the point where the ecu is chucking in 100% duty when on boost.

Anyway as said did you fill up to check that the gauge is right?

There is a test somewhere that you can do to see if the Lambda sensor is faulty, think its in the BGB somewhere.

[amnesia]

Can a worn distributor cause poor fuel economy ?

I checked mine at the weekend whilst I was waiting for my gearbox oil to drain, and noticed that both the rotor arm and contacts in the dissy cap were well worn. I cleaned them up carefully and the car feels much more responsive now

Guess what's on the shopping list this week ???

[mrfil13]

depends how worn it is, if its really worn i would expect to have misfires something noticible. If its slightly worn i suppose it could create a weaker spark but really if your not using boost the lambda sensor should look at the fact thats theres unburnt fuel and lean the mixture a little.

[Olly P]

Tubby owners how heavy are your feet, the lowest ive had in my turbo so far is 26mpg, got 38 mpg on the way back from london up the m1 My N/A used to get around 28-30 mpg.

I think it's more the fact that I'm running 1.2bar of boost, have a Mines ECU which has more agressive fuelling, only drive short journeys, and boot it around like a cnt

[mrfil13]

Tubby owners how heavy are your feet, the lowest ive had in my turbo so far is 26mpg, got 38 mpg on the way back from london up the m1 My N/A used to get around 28-30 mpg.

I think it's more the fact that I'm running 1.2bar of boost, have a Mines ECU which has more agressive fuelling, only drive short journeys, and boot it around like a cnt

i drive mine like an old granny

[StuartLaws]

The last time I had a significant drop in fuel economy it was due to binding brake calibers. After you've been out and about check for excess heat from the calibers, as that is the easiest indication that something isn't right...

[RST]

Might seem like a random question, but do you still need a small breather filter still for the idle control hose with the Apexi kits?

Just asking because your garage says it was fitted in September and this has arisen since.

I tried a breather filter on my rev 2 with a Power Enterprise kit and the fuel economy dropped to pretty much the same figures (about 160miles to a full tank). As soon as I took it off again -and replaced the pipe back to the induction kit (like it is on the stock arrangement), my fuel economy instantly returned to normal (300miles +).

...Just thought it was worth asking -not sure if it's the same problems I had but sounds very similar.

Richard

**edit, sorry I should have said at that time I had a stock 3SGE**

[luthor1]

do 10 miles down the motorway at (high)mph, then pull off carefully and gently, get out and feel how hot the wheels are (DON'T touch the discs!) uneven temperatures indicate brake binding, and this can devastate your mpg.

My rev2 went from 130 a tank to 200 a tank by freeing up sticky calipers.