106 GTI fuel problems

18th April 2010, 00:37

Hi all,

So, i'm still not too sure why my car is so crap for fuel economy.

I've changed the oil filter and oil (not cheap stuff) as well as the fuel filter and fuel breather valve as mine was broken and pissing out fuel but today i got into the warning light for fuel and then filled it up with a tenner which got me out of the red and upto about 40 miles so by my calculations thats just less than 20mpg but obviously it had to fill up the reserve a bit.

This was mixed driving but shouldn't i be getting about 60 miles from a tenner at least?

Any ideas why it's being like this? Also when my car sits at traffic lights etc... the idle goes up and down sometimes. The battery has been disconnected so the ecu would have reset but my car is a bit modified.

Modifications includes:

Engine work (i'm on the understanding that it has a skimmed head, port and polished but i know the cams are standard, but i beat my mates 150bhp GTI and also slaughtered a BMW 325i saloon (192bhp) off the lights and also give a Honda Civic Type-R's a good run for their money, including beating one down the motorway, so i know im not running standard. Also have an aftermarket air filter and Blitz Subaru 4" backbox.

So what is the next thing to check? Lambda sensor? Map Sensor? How would i clean them? Take them out and spray them with WD40? I know the Lambda is in the manifold, but what about the map sensor? Anything else other than these?

Will my new 206 1.6 16v head make a difference when that is fitted?

Thanks in advance,

Andy

18th April 2010, 00:43

Easiest thing to do is take it in for an exhaust gas analasys, or just get it MOT'd and they will do that anyway. It will tell you a lot and if your lambda is playing up it will show.

But why are you wnating to put another head on if you are already getting blistering performance?

18th April 2010, 00:45

It had an MOT about a month ago where i had to purchase a new CAT and it passed due to that. They also run a diagnostic and things all came up fine.

Can't wait to get my Predator ECU lol

I want to fit throttle bodies soon so the 206 head is the way forward to be honest and the fact my rocker cover likes leaking every so often hence the change (replaceable seals)

Andy

18th April 2010, 08:48

You say you had an MOT a month ago but didnt say how long you are having crap MPG, is it more recent?

If you are modding then your MPG will fall, cant have it both ways

18th April 2010, 10:26

Was bad before and i obviously thought it was because it needed a service and the one way fuel breather valve was broken but now i've changed all that, it's still not fantastic.

Andy

18th April 2010, 20:06

Well i had my fuel light come on yesterday and drove around for a fair bit into the reserve, and since then have put £30 in the tank and am on 142 miles so far and no fuel light yet.

Any ideas how much that works out as MPG so far?

What should i be hitting for £30 of fuel?

Tuned 106 GTI by the way

Thanks,

Andy

18th April 2010, 20:26

£30's worth is about 6 gallon at todays prices so i would expect to get about 200 miles or so

19th April 2010, 01:29

Well, it turns out it did 170 miles.

Why is it so low

I stuck to A roads mainly with a bit of dual carraigeway.

Andy

19th April 2010, 13:22

Any ideas why its so low anyone?

Thanks,

Andy