Fuel usage

I have a 2000 Pontiac Grand Prix GTP. I only getting 180 miles out of a full tank of fuel. What could be causing this problem? I have replace the fuel filter and air filter. What else can I do to increase my gas mileage?

I believe if you remove the u-bend in your exhaust it will give you a slight increase in gas mileage... that's all I can think of. I'm sure there's probably more though.

I have a 2000 Pontiac Grand Prix GTP. I only getting 180 miles out of a full tank of fuel. What could be causing this problem? I have replace the fuel filter and air filter. What else can I do to increase my gas mileage?

what octane are you buying?

Lots of stuff can effect your gas mileage...

tire pressure, are all tires set to proper inflation?

are you driving around with performance shift on all the time? (I think 2000's had that), if so, that is good for a 2-3mpg loss

have you had your injectors professionally cleaned lately? Running BG 44k through the fuel system is almost as good...

have you used GM top engine cleaner yet? very good stuff that gets rid of carbon deposits...that can rob gas mileage\power

fuel filter and air filter changed already

your plugs should still be in good shape...

how do you drive it? are you going for maximum gas mileage or do you peg the redline alot? that is the biggest factor...restraint :nono:

Lots of stuff can effect your gas mileage...

tire pressure, are all tires set to proper inflation?

are you driving around with performance shift on all the time? (I think 2000's had that), if so, that is good for a 2-3mpg loss

have you had your injectors professionally cleaned lately? Running BG 44k through the fuel system is almost as good...

have you used GM top engine cleaner yet? very good stuff that gets rid of carbon deposits...that can rob gas mileage\power

fuel filter and air filter changed already

your plugs should still be in good shape...

how do you drive it? are you going for maximum gas mileage or do you peg the redline alot? that is the biggest factor...restraint :nono:
well I never peg the red line at all and I never use performance shift do you think that it may be my fuel injectors

are you an agressive driver....mostly City Driving?

First of all where do you live. IF you live on a big city mileage would always will be worst. Did you changed the tstat?(A cooler tstat means worst mileage, on my 98 after installing the 180degf tstat the mileage per gallon dropped from 19.9 to 18.4). Did you checked the tires pressure, Are U certain the air and fuel filters are clean. Would not hurt cleaning your fuel injectors. If you feel like it take out a spark plug and check the tip color. If is light tan or almost normal they are burning fuel correctly if not then depending on the color is how the fuel/air mixture being developed. Too lean can harm the car(In my case broke a piston on heavy load) if it is too rich then you would be wasting gas. And of course your driving style. IF you are an aggresive driver the mileage would go down.

Here are my mods:

-- 160 T-Stat
-- TB Heat Shield
-- Custom FWI
-- 3.25 S/C Pully
-- GatorBack Belts
-- R/T DownPipe
-- R/T HighFlow Cat
-- ZZP Motor Mounts
-- Poly Bushings
-- Tinted Windows
-- DHP PCM(Beta Tester)
-- Intense Gen 3 Rockers
-- PRJ Wires
-- Clear Corners
-- 105# Springs -- not installed yet
-- Titanium Retainers -- not installed yet

I am getting 20 miles to the gallon....about half city/half highway

CATz, the TB shield was custom built? If not where did you got it. I am thinking about getting one custom level 2 or 3 tb from http://www.intense-racing.com but keeping it cooler makes sense

First of all where do you live. IF you live on a big city mileage would always will be worst. Did you changed the tstat?(A cooler tstat means worst mileage, on my 98 after installing the 180degf tstat the mileage per gallon dropped from 19.9 to 18.4). Did you checked the tires pressure, Are U certain the air and fuel filters are clean. Would not hurt cleaning your fuel injectors. If you feel like it take out a spark plug and check the tip color. If is light tan or almost normal they are burning fuel correctly if not then depending on the color is how the fuel/air mixture being developed. Too lean can harm the car(In my case broke a piston on heavy load) if it is too rich then you would be wasting gas. And of course your driving style. IF you are an aggresive driver the mileage would go down.

By they way thanks fot your help the previous post.I live in Atlanta Georgia, but drive only about 30 miles a day round trip in the mornings I usually take the street way to work and in the afternoon I take the expressway

Well the street is a little bit ample. The only car that has better mileage on the stop/go traffic is the Toyota Prius. Because it converts stopping motion into energy to be used by the electric motor. Besides that everything else would behave worst mileage on the stop/go traffic.
And if you drive your car normally then the only thing I would think of is performing a tune up just for the heck of it. Change the air/oil/fuel filters, Change PCV valve, Instead of using D use the tranny in 3 on the stop/go traffic. Make sure the car is cool but not too cool(Keep 195degf tstat), clean the tb butterfly and sorounding areas with gumout. Did your car passed emition testing? I do not know why you would get bad mileage. How do you meassure mileage, by the trip computer? Or you just add up miles that you run on a full tank? What was your previous car? Because if the car has always been like this and your previous car was a Susuki 3 cylinder then the difference is noticeable

Are you going off the trip meter or actually filling up and resetting the trip odometer??

I run a 160 tstat and a big cam and still see better mileage then you. I see around 21 mpg back and forth to work

Oh ya, same mileage on 93 oct and 89 oct.

Well the street is a little bit ample. The only car that has better mileage on the stop/go traffic is the Toyota Prius. Because it converts stopping motion into energy to be used by the electric motor. Besides that everything else would behave worst mileage on the stop/go traffic.
And if you drive your car normally then the only thing I would think of is performing a tune up just for the heck of it. Change the air/oil/fuel filters, Change PCV valve, Instead of using D use the tranny in 3 on the stop/go traffic. Make sure the car is cool but not too cool(Keep 195degf tstat), clean the tb butterfly and sorounding areas with gumout. Did your car passed emition testing? I do not know why you would get bad mileage. How do you meassure mileage, by the trip computer? Or you just add up miles that you run on a full tank? What was your previous car? Because if the car has always been like this and your previous car was a Susuki 3 cylinder then the difference is noticeable

well my previous car was a 1993 pontaic grand Prix SE coupe. I got almost 400 miles out of a full tank of gas but 1993 had a 3.1 engine and the 2000 has a 3.8 supercharged engine, by the way I am going by the analog trip counter