my gtp using to much gas

my gtp is using to much gas and i dont know how to get better gas milage,what do i have to do to get better gas milage.

Keep your foot out of it.

Have you ever changed the Fuel filter and PCV and spark plugs????......~Larry~

What kind of milage are you getting?
Before I installed airbox, and pulley, I was getting 17 to 18 MPG. Now I get 15. So we need to know what you are calling "bad".
http://img.photobucket.com/albums/v425/kustomkid54/kustomkid.jpg

Probably time for a full maintanance overhaul. What year is it and what mileage? Any mods? What kind of mpgs are you getting?

Might be time for some of this stuff...

Fuel filter
air filter (if not K&N)
pcv valve
prof Injector cleaning or BG44k
throttle body cleaning
intake manifold\induction cleaning (gm top end cleaner or BG)
tire pressure set at the correct levels and properly rotated
plugs\wires depending on mileage

Still don't know what milage the car is getting. This guy could be getting 18 to 19 MPG.
http://img.photobucket.com/albums/v425/kustomkid54/1998PontiacGrandPrixGTP004.jpg

im getting 12 miles to the gallon and havent done any modofications to drain more gas

i'ld take up on big-l and replace the fuel filter, air filter, pcv valve, and plugs. also a little intake cleaning couldn't hurt.

I'd listen to everyone and do the whole 9 yards. 12 MPG is way too low for that car, stock. You should be around 18 city.
Pull a couple plugs and see what they look like.
Must of the GTP on this site are not close to being stock, but they are still getting around 15 to 16, depending how many times they get into them.
Good luck
http://img.photobucket.com/albums/v425/kustomkid54/1998PontiacGrandPrixGTP004.jpg

Im getting 18-22 mpg on mostly highway miles

Biggest thing after you do all of the above stuff is just not flooring it when only light acceleration is needed. You burn a huge amount more gas acceleration than you do when you just keep speed, to dont slow down when you know you will have to speed up again unless you have to. I get like 16 (pretty much all in the city my car is totaly stock, but i have this thing for acceleration. im in football season right now so im waiting to modd it untill afterwards when i have more time. getting an intake and exhaust and strutts and the gmpp handling upgrade package and polyurethane upper motor mounts and a 180 tstat. i dont really trust myslef w/ a smaller pulley right now w/ the whole gas milage thing. Im expecting a little increase in economy from the intake, when im not flooring it at least, plus im sure ill calm down off of the pedal after a while. ne way just wondering if it would help to got to 1 (or however many) heat range(s) colder spark plugs after the light modding? The whole colder range spark plugs thing is still kind of beyond my knowledge, so explaination of this would be nice too.

ne way just wondering if it would help to got to 1 (or however many) heat range(s) colder spark plugs after the light modding?

Being that your car is stock its would be best to use the stock plugs ACDelco 41-101s and gap them at .058

The reason people go with colder plugs on a modified GTP is for KR,which pulls timming and we lose horsepower...Check out this thread and it will help explain KR

http://www.zzperformance.com/zzp/info/knock_retard/kr_about.htm

A general guideline for which spark plug heat range is right for your modified supercharged vehicle, are as followed:

- Use AutoLite 605's (one heat range colder) if your car is similarily modded like this: has a 3.40" supercharger pulley, CAI (cold air induction) setup, and a lower-temp thermostat.

- Use AutoLite 104's (two heat ranges colder) if your car is similarily modded like this: has a 3.25" supercharger pulley, 1.80:1 or 1.90:1 rocker arms or very mild cam, CAI setup, lower-temp thermostat, exhaust headers, cat-back exhaust system, and reprogrammed PCM.

- Use AutoLite 103's (three heat ranges colder) if your car is similarily modded like this: has a 3.0" supercharger pulley, 1.90:1 rocker arms or aggressive cam, CAI setup, lower-temp thermostat, exhaust headers, cat-back exhaust system, port and polished supercharger housing and/or throttle body, and reprogrammed PCM.

It is recommended that you set the gap on these to .055"-.057".

cool thanks