Bad Gas Mileage [Merged 9-6]

[99GST]

I am still getting some pretty bad gas mileage.

I am only getting about 19.7 mpg with mostly city driving shifting at 4k.
I have already replaced my front O2 sensor and am looking to replace the fuel filter.

I have a 99gst with about 55k miles on it. Should my fuel filter already be bad?

What else should I check or change? I have NKG plugs and Accel wires are on the way.

Thanks,
Nathan

 

[talontsiawd05]

somebody?

 

[cucooman]

Hey guys,

I ve got a 91 TSi with rewired pump and free mods. This is the deal, I filled up on gas and twice this has happened. I am at half a tank with only 96 miles from reset at last fill up. Any thoughts and as to why this is happening. Its happened since its been cold. Im starting to get sick of only going 175-200 miles on a tank of gas. I dont race that often being its winter here in Kenai, Ak. Any thoughts would be appreciated. Thanks

Dan

 

[pneumo]

It could be the cold up there. How long does it take the engine to warm up? The ECU runs the engine richer until it's warmed up, which I think is above 180 degrees.

 

[laserturbo91]

ive been getting around the same, a little more range on a tang, but i also think i have a heavy foot, and i like the turbo, a lot...offnote, the turbo does just more fuel when its being used, so maybe thats why. my dad once had a 92' tsi, old man, but he claims he got 32mpg because he would shift before the turbo would kick in, why im not sure, shouldnt have gotten a turbo then, oh well

 

[herostar]

you might have an oxygen sensor going out...

 

[Enigma_Man]

Yeah, a dead or dying oxygen sensor can really cut down on the gas mileage. I would suspect that first.

If you have one, or know someone that does, hook up a logger or a real gauge (not the autometer blinkey one), and watch the O2 voltage. If it doesn't fluctuate up and down while just cruising around, then it's dead.

Mine went bad, and I got bad mileage too. Diagnosed it (no check-engine light came on) with a logger, replaced it, back up to 22 mpg.

BTW, I have a lead foot too, and I still get 22 mpg. So something is def. wrong if you get less than say like.... 17 mpg.

-Jesse

 

[mike9146]

In addition to what has already been suggested, check the ground strap on the DP. That has been known to cause a whole bunch of weird problems.

Mike C.

 

[FourG63 97GST]

I was having bad gas, so i checked for exhaust leaks, found 3 of them.
fixed them, now i have good gas

 

[mrfloppy]

Originally posted by cucooman
Hey guys,

I ve got a 91 TSi with rewired pump and free mods. This is the deal, I filled up on gas and twice this has happened. I am at half a tank with only 96 miles from reset at last fill up. Any thoughts and as to why this is happening. Its happened since its been cold. Im starting to get sick of only going 175-200 miles on a tank of gas. I dont race that often being its winter here in Kenai, Ak. Any thoughts would be appreciated. Thanks

Dan

okay i didn't read the other posts so if the question is answered, sorry.

first off did ya up the boost at all??? normally more boost... more power.... more fuel. second off what free mods have you done? did ya remove the honeycombs on the MAS? if so that will also cause your car to run funky at idle and it will help you loose gas. i was getting 23 now i am down to 18 with that free mod.... its worth it though! the fuel pump rewire will send more fuel into the engine.... thus your gas mileage goes down.

 

[UltraImports]

Originally posted by FourG63 97GST
I was having bad gas, so i checked for exhaust leaks, found 3 of them.
fixed them, now i have good gas

:laugh: I'm sorry....it just sounds funny

 

[25psi]

Your BOV is stock right? If you are venting that really kills your gas mileage.

 

[96TalonAWD]

Originally posted by mike9146
In addition to what has already been suggested, check the ground strap on the DP. That has been known to cause a whole bunch of weird problems.

Mike C.

i just got a RRE DP the full one that replaces the cat, the muffler shop cut out the ground strap you talk about since them i get 115 miles for 6.4 gallons like half ttank. is there a fix for that now

 

[Mitsubabe]

How about something simple also like your tire pressure. If they get real low that makes it appear that you're not getting good gas mileage.

 

[mrfloppy]

Originally posted by 25psi
Your BOV is stock right? If you are venting that really kills your gas mileage.

what the hell are you talking about??? venting where??? intake? atmosphere? i don't think gas mileage has anything to do with it.

 

[mrfloppy]

Originally posted by Mitsubabe
How about something simple also like your tire pressure. If they get real low that makes it appear that you're not getting good gas mileage.

i way over looked this one. thats so true... the saggy the tire the more the traction the less the fuel mileage. pump them up to there max rating if there shitty tires, then see where it goes from there. but i am sure that its your mas.

 

[UltraImports]

Originally posted by mrfloppy


what the hell are you talking about??? venting where??? intake? atmosphere? i don't think gas mileage has anything to do with it.

I believe he meant atmousphere. When you do so, you tend to run rich, hence bad gas milage.

 

[FourG63 97GST]

you run rich between shift vented to the atmosphere. but he has a 1Gbov, hopefully he's not venting, right cucooman. whats a cucooman anyway?

 

[doug]

Originally posted by 96TalonAWD
i just got a RRE DP the full one that replaces the cat, the muffler shop cut out the ground strap you talk about since them i get 115 miles for 6.4 gallons like half ttank. is there a fix for that now

Yeah, put another ground strap back on it.

 

[L2RTSiAWD]

Deleted an argument that had nothing to do with anything.

 

[mrfloppy]

Originally posted by L2RTSiAWD
Deleted an argument that had nothing to do with anything.

thanks!

 

[Psycron]

Ok, here's the deal...I bought my 92 Laser AWD about a month ago and I'm slowly fixing all the probs with it. The latest problem is my mileage -I swear a mustang V8 gets better mpg than I do! I drove about 80-100 miles and burned half a tank of gas. Are AWD tanks smaller? Even with freeway miles I'm still getting 250 to the tank.

Could it be my o2 sensor going south or something? Car seems to run fine. If my mpg is this bad right now, I can imagine what it'll be when I get an L1R

 

[L2RTSiAWD]

Look at all my mods and I'm getting 250 to a tank.

AWD tank is 14.7 gallons I beleive.

 

[rubbersidedown]

the tank on my '94 gsx is only about 12 gallons i believe. I tried to figure out by watching the gas guage and seeing when the gas light comes on and just a lot of experimentation But yeah, generally i only get about 200miles to a tank, but i get some killer highway miles.

 

[Psycron]

so AWD sips more gas than FWD? My FWD was getting like 275-300 a tank. Is there anything I can do to get better mileage? S-AFC maybe? Seems like the computer is inefficient in mixing the air/fuel ratio. FWD must also hold more fuel than the AWD tank. My turbo doesn't spool until about 4k, maybe that has something to do with it (housing has some cracks in it)?

 

[c5chris]

My GSX has a 15.9 gallon tank. I go 18-20 mpg on city/highway commute. Thats 220-250 miles before the fuel light blinks. Is that normal?