I filled my tank two weeks ago and just killed off the rest of my tank last night. I did the math and was shocked to find out I only got 185 miles to that tank. The mpg came out to 11.9x. My mods in sig. I will check the fuel pressure again today to see what is up. Most everything is new. Only 3,220 mile on the engine/tranny swap(from 88 formy 350). Timing set to spec, and it runs great. No idle issues or drivablitiy problems. Any ideas or thoughts at the problem? That is horrid mph.

Thanks,
Conrad

 

that good mileage my 88 GTA gets 150-160 miles per tank full and that with out the supercharger hooked up.

 

I'll say that's bad...I get 395 miles to a tank

 

I think you better do the math again or did you really put 15.5 gals in or just assume you filled it to that amount???

 

Last time I went to the gas(rip off) station I waited till my gauge did not even show I had fuel(station is across the street). Then I fill it till it showed 15.3x on the pump,maked the mileage down and off I went. Now it sits in the garage with no fuel showing on the gauge(gta digital dash). I thought I made a mistake in my math, or I hope I did, but no it is just crappy mpg.

Conrad

 

The best way to check mileage is to fill 'er up, drive most of it out, and then see how much it takes to fill 'er up again, but anyway....

That is terrible mileage if you are talking highway. I just checked mine two weeks ago and got about 25 MPG average in some mixed driving, but mostly highway. 268 miles on a little under 11 gal. of gas.

My car has only the most basic bolt-on mods.

UD pulley, cat-back exhaust, chip, K&N's, and ign. coil upgrade. Oh, and I just replaced the Multec injectors with Bosch/Ford injectors but the car got good mileage before the Multec injectors took a dump. The rear end is 3.23.

If you are taking mostly city driving, then it's probably not too far off, but I've never checked my in-town mileage. Depends a lot on how you drive too.

 

with mine i get around 310 or so highway miles on a fullt ank and thats with fillin it with around 12 gallons

 

I get 135 miles to a tank! It is a carb'd 305 86 Iroc-Z. I am not able to get into 4th gear so I pull a lot of rpms all the time driving to work. I have 3.23 gears. I am putting on a TPI set-up very soon and gonna rebuild the tranny. I really expect everything to increase my mileage dramatically.

 

I can get upto 300 per tank if I do mainly highway driving and keep it under 100.
City driving gets me about 170 or less since I am way too hard on the pedal.

The other night I used up about 1/8 to 1/4 tank in about 10 miles cruising at 140mph. (5K rpm in 5th gear)

 

Here's my car, I can get around 230-240 only city driving, but at the most for 95% highway is around 280mpt. What gives? I just replaced my fuel filter today and a new oil change. My car needs an alignment. I heard that could suck gas like crazy.

But yeah, your city mileage is horrible, like I said I get 230-240 in the city. And that's having a few WOT runs every so often. I have a tpi 5.0 auto/2.73 T/A.

I am at 2 ticks below 1/2 tank and I am at 210 miles. I hope to hit 300 this time. And next tank, hopefully after the alignment and 1.5oz of acetone, I hope to go above that by 10%.....again I hope.