Poor gas mileage

I have a 97 GTP

On a full tank of gas I could get around 360-370 Miles before low fule light on. The car has 136,756 miles on it. That is with a mixture of city and highway driveing. I Changed the plugs and wires about 10,000 miles ago. I just changed the fuel filter and air filter. The reason was because now I get about 310 miles per tank before the low fuel light comes on. After those changes the mileage did not change.
Also, it has a digital display that would read about 428 miles when I filled up the car. Now it reads about 298-313 miles. Also my miles per gallon used to read 28 MPG now it reads 20.3MPG.

1. Does anyone have an idea, O2 sensor maybe, (how many are on this car)
2. How big is the gas tank?

I have a 97 GTP

On a full tank of gas I could get around 360-370 Miles before low fule light on. The car has 136,756 miles on it. That is with a mixture of city and highway driveing. I Changed the plugs and wires about 10,000 miles ago. I just changed the fuel filter and air filter. The reason was because now I get about 310 miles per tank before the low fuel light comes on. After those changes the mileage did not change.
Also, it has a digital display that would read about 428 miles when I filled up the car. Now it reads about 298-313 miles. Also my miles per gallon used to read 28 MPG now it reads 20.3MPG.

1. Does anyone have an idea, O2 sensor maybe, (how many are on this car)
2. How big is the gas tank?


Right now my GTX gets 16.4 MPG. Has a lot less miles then your's.
I'm happy with mine.
Depends on how you drive. Lead foot gets bad mileage.
20 MPG av. is about normal around here. The 28 you were getting, has to be a lot of highway miles.

I have a 97 GTP

On a full tank of gas I could get around 360-370 Miles before low fule light on. The car has 136,756 miles on it. That is with a mixture of city and highway driveing. I Changed the plugs and wires about 10,000 miles ago. I just changed the fuel filter and air filter. The reason was because now I get about 310 miles per tank before the low fuel light comes on. After those changes the mileage did not change.
Also, it has a digital display that would read about 428 miles when I filled up the car. Now it reads about 298-313 miles. Also my miles per gallon used to read 28 MPG now it reads 20.3MPG.

1. Does anyone have an idea, O2 sensor maybe, (how many are on this car)
2. How big is the gas tank?
You can call your nearest dealer service and find out the info on o2 sensor and the fuel tank is 18 gallons. Avoid jackrabbit starts and get into overdrive as soon as possible.

Driving situations have not changed, still drive the same just, noticed a huge difference in mileage per tank 370 compared to now 313.

1. Does anyone have an idea, O2 sensor maybe, (how many are on this car)
2. How big is the gas tank?


We have 2.1 upstream for A/F and the other downstream that moniter's the cat

Ive heard 18,but 5 gallons of the fuel is there for keeping the fuel pump cool.

With that many miles id say it may be time to replace the upstream O2 sensor.Ive heard they should be replaced around 5yr's/100,00 mile's on heated O2's.

How offten do you reset the MPG in the DIC ?

~Larry~

BIG-L:

Did not know you could reset the MPG on DIC. I have had the MPG displayed and hit the reset button next to the display but did not see any change.

I believe I will change the O2 sensors, if nothing else it sounds like they are do.

Thanks

Did not know you could reset the MPG on DIC. I have had the MPG displayed and hit the reset button next to the display but did not see any change.

Need to hold the reset button down untill it clears, 0.0 mpg then take your regular drive.I always reset mine when I go on long trip's or after doing a tune-up.

Also how long has it been since you replaced fuel filter and PCV ???

~Larry~

Never replaced PVC, But just last week changed air and fuel filter

Here are some instruction's for replacing the PCV Click Here (http://macgp.clubgp.com/howto/pcv/pcv.html)

Thanks alot BIG L

If your going to buy an O2 sensor,you may want to check out Ebay.I got one awhile back for almost 40 buck's shipped.Dealer price is close to 120 and please dont use a BOSCH O2,as they dont last very long on our cars (97/03 GP)

AC-Delco part # is AFS109.

What I used to replace mine is a 1/2 ratchet,5 in extension and a 7/8 O2 Socket and mine would not turn once I warmed the engine up some.So I had some PB blaster,that is the best stuff to spray at the bottom of the O2 that helps penetrate the threads.

http://www.pbblaster.com/store/images/PBCatalyst.gif

BIG-L

Thanks again for all the info. I will check ebay. It just happens I have a can of PB just waiting to be used.

Here is an O2 sensor.It's a buy it now for 38 bucks and they have 13 available.

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=7958576722&category=33557&sspagename=WDVW

BIG-L

Thanks,

Funny, I was just looking at that item.