New Here, Fuel Mileage

[cowmilker08]

What kind of mileage should my fiance's '97 GP GT get on the highway,? It has 107k miles on the clock.

[Bio248]

if it is in good running condition maybe in the higher 20s? if not, 18-22 like i get.

[NaturallySmashed]

26-27 mpg

[cowmilker08]

well when she drives it for the majority of a tank its usually 18mpg but if i drive it for the majority of a tank its about 21. it seems to run very well.

Edit: Last summer when it didn't see many highway miles it was only getting about 15-16mpg!

[Bio248]

seems normal to me.

[dstout]

Most of the time I get between 18 and 24 but it depends on how I feel sometimes it's less than that.

[Nick22]

god damn i have a 97 gp with 142,xxx and i get about 10 mpg around town. 155 miles before i have to fill it up again

[Bio248]

god damn i have a 97 gp with 142,xxx and i get about 10 mpg around town. 155 miles before i have to fill it up again

that is super low and i bet something is wrong with your car and needs to be replaced.

[StreetChariot]

'00 GP SE here with a '97 Monte Carlo 3100 (3.1L) engine which was totally rebuilt.


I average between 27-36mpg depending on how I accelerate / how much city driving I do. I can get between 380-500 miles per tank. (500 miles is strictly freeway driving).

I knew I had a bad O2 sensor last week because my fuel economy dropped to 14 MPG. As soon as I replaced it, I'm right back at 28.9 MPG.

As for your bad gas mileage, are you getting a SES light?

If not, how old are/how are the condition of the following items: Air filter, fuel filter, PCV valve, EGR valve, O2 sensor(s)?

[Blacknight02GT]

If its all highway she should at least be getting 29-30mpg. I drive about 50 or 60 percent highway, and usually average 26-27mpg out of a tank in the summer;but only 23-24mpg in the winter. I've never once gotten below 20 out of a tank under any circumstances.

[Nick22]

mechanic was going to give it a shot and change the 02 sensors. how much do they run for 2?

[StreetChariot]

O2 sensor will run you between 50-90$ depending on where you buy it.

I just purchased my O2 sensor for 52.99$.

Bosch brand 15732 part number I believe... It was the kind where you cut off and re-use your factory harness... 12$ cheaper than the OEM Bosch part which had the connector. It's not a big deal. It includes the junction box, connectors, water-proof bushings, etc and the instructions are good for those who may need them.

My biggest word of advice would be to rent the O2 sensor socket set, or buy one... Do not use a standard 22mm deep head socket, as you will ruin the wiring.

[cowmilker08]

Well i'm new to this car, and as far i know the only maintance that gets done to it is the yearly oil change. Yes i tell her that isn't often enough, but ya know. How bad is it to change the O2 sensor(s)? I'm more of a diesel guy so bare with me. (I pefer a MAP to an O2 lol)

[cowmilker08]

well fiance says that a sensor was changed a while back becuase the car kept dying, i checked the air filter early last fall and it looked so i blew it out with an air hose, and put it back. how can i tell if the PCV valve or EGR valve is plugged/malfunctioning? If the fuel filter needs changed how do i do it on this car?

[StreetChariot]

The PCV is plugged in on the top of the engine... It is a cheap part (3-7$) and plugs into a hose on one end and the valve cover on the other... it acts as a vacuum regulator to keep the pressure on the top end of the engine correct in comparison to the intake.

As for the EGR... you would more than likely have a SES light... And the car would choke out due to exhaust backing up in the exhaust headers.

[cowmilker08]

well no light so the poor mileage could be cuased by the PCV valve or O2 sensor? What about the possibility of the CAT getting plugged, What signs would that show?

I'd kinda like to know why last summer my truck got better fuel mileage than the car. LOL, she blows alot of smoke when i get on it so the car should be doin' way better than the truck.

[dstout]

You should clean the MAF sensor, I cleaned mine and it helped with my mileage. Just a thought. You might want to run some Seafoam through it too to clean out some of the carbon and crap. If you do decide to do Seafoam you will have to change the oil and prob. the spark plugs too. Those things will help some.

[chad27]

Mine is between 19.6- 20.7 city

[Crave Energy]

I get almost 21 MPG on combined driving, my wife has gotten over 30 MPG in hers with just freeway driving.