Poor fuel economy 1.8T

[jaysleeves]

Re: Poor fuel economy 1.8T

So I got a ross-tech cable and scanned the car. No fault codes!! O2 sensor regulation is ON, I couldn't find anything wrong. Only faults I got were no communication with Multi-Function wheel (cause I swapped it) and a problem with my drivers door lock (never locks with fob, always unlocks no prob) and thats all I got!

I have just under a 1/4 tank left and it's about 270km's on the trip odometer :(

[jaysleeves]

Re: Poor fuel economy 1.8T

Start with the cheapest and easiest of things. When was the last time you changed your fuel filter?

Haven't at all. Bought the car in June 2010 with 112K on it, I'm almost at 140 now. That will be the first thing I replace along with cleaning my air filter (put it on maybe 10K ago) and changing that boost gauge line from the FPR to an open port on the intake mani. Till I get it scanned I'll see what this does.

Thanks for all the suggestions!

[danosaur]

Re: Poor fuel economy 1.8T

Start with the cheapest and easiest of things. When was the last time you changed your fuel filter?

[idlandk]

Re: Poor fuel economy 1.8T

I also get 600/tank city with my 1.8t with stage 2. 450 is driving it pretty hard

[kujiwara]

Re: Poor fuel economy 1.8T

interesting!


so who's got vagcom and wants to come give me a scan?!

I'll scan your car if you are willing to drive up to edgemont.

[Geobmx4life]

Re: Poor fuel economy 1.8T

Get ahold of 12 beer..then Colin....you may have to drive out to spring bank depending lol

[jaysleeves]

Re: Poor fuel economy 1.8T

interesting!


so who's got vagcom and wants to come give me a scan?!

[Lars]

Re: Poor fuel economy 1.8T

I get 600 km to a tank Unitronic 1.5 tune ... And that was with a bad o2 sensor, don't think I've ever got worse then 500 km in city driving in winter

[jaysleeves]

Re: Poor fuel economy 1.8T

I think 450 in the city is about normal for a 1.8T....my 2.0L was about 600/tank in the city.....can't see it being a leak.

I need vagcom!

[kujiwara]

Re: Poor fuel economy 1.8T

If you have a leak that affects your mileage that badly wouldn't you have quite a strong smell of gas around and inside the car?? I had a leak and it was pretty bad inside the cabin...

Nope, I never paid attention.

[tirerub]

Re: Poor fuel economy 1.8T

Id start as Dylan said and get some logging done, something is defiantly up with the mileage and the dyno.
I still get like 400 to a tank with 830cc injectors
Do you know what you're afr is like at part throttle ?

[BolideVW]

Re: Poor fuel economy 1.8T

If you can get a hold of vcds you can log blocks 30, 31, 32 (or something along those lines) and you can see if you fuel trims are adapting. Also check block 99 to see if o2 regulation is turned on.

If any of those show negative results it's likely a bad resistor or a wiring issue. If not, it's most likely one of the issues others have mentioned

[Ur0Drivr]

Re: Poor fuel economy 1.8T

Well.. I'm driving a vr6 like I stole it every day and average 400 per tank so I think your jetta had a little bit of problem to start with.
This may sound a little strange but my BMW had a very leaky fuel line, and i did about 175km before it ran out, I couldn't figure out the issue because gasoline evaporates on the ground, i fixed the leak and 450+ per tank easily. I suspect you have a bad fuel leak somewhere in the system, a clogged maf or o2 sensor shouldn't make it that bad.

If you have a leak that affects your mileage that badly wouldn't you have quite a strong smell of gas around and inside the car?? I had a leak and it was pretty bad inside the cabin...

[kujiwara]

Re: Poor fuel economy 1.8T

Well.. I'm driving a vr6 like I stole it every day and average 400 per tank so I think your jetta had a little bit of problem to start with.
This may sound a little strange but my BMW had a very leaky fuel line, and i did about 175km before it ran out, I couldn't figure out the issue because gasoline evaporates on the ground, i fixed the leak and 450+ per tank easily. I suspect you have a bad fuel leak somewhere in the system, a clogged maf or o2 sensor shouldn't make it that bad.

[jaysleeves]

Re: Poor fuel economy 1.8T

Is the engine running ok or does it seem to bog down at all? Like does it seem like it is getting too much fuel

runs fine as far as I can tell....maybe this has something to do with my low dyno numbers too (175hp at the wheels)