12 MPG or less!

I have a '95 GTP with the 3.4 DOHC. I'm getting around ~12 miles per gallon. All i do is drive to school and back every day Mon-Fri. Most of the way to school is highway, where im doin around 65 with o/d kicked in runnin about ~2,000 rpm. I dont get on it at all. .....I'll name some of the problems it has, maybe that will help pin poin what the problem is b/c im on an extremely tight budget. It has a rough idle, and when you first take off from a dead stop it's sluggish untill it gets to about 2,000 rpm and up. When i first start it up in the mornin and after school, or whenever it has sat for a long time, it blows a puff of bluish smoke out of the exhaust, but then after that it doesnt smoke anymore at all. The ABS and !Brake and SRS airbag lights are on at all times. other than that, it has all the factors that should get good mileage....i dont get on it, it has brand new tires and they all have the same amount of correct pressure, it has been aligned not very long ago too... Any suggestions at all would be greatly appreciated, Thanks ahead of time!

I had similar problems. So I did the injector cleaning service through QLube and that did nothing. Actually even worse, I failed emissions after doing it.

I have a '95 GTP with the 3.4 DOHC. I'm getting around ~12 miles per gallon.
When i first start it up in the mornin and after school, or whenever it has sat for a long time, it blows a puff of bluish smoke out of the exhaust, but then after that it doesnt smoke anymore at all.

Have you ever changed the plugs,fuel filter,pvc and spark plug wires and the smoke that happens at start up sounds like bad valve seals.How many miles on your car????

~Larry~

I have 70K now but had about 60K when I did the fuel injector service. I'm not a mechanic or even good under the hood, so I haven't done what you hve said. I like your car, BTW. That's exactly what I have - a red 4 dr. GTP but with the less attractive alloy wheels.

I drive a 97 Grand Prix GT and get 19.7 MPG, does that sound right? is there any way to improve it?

I drive a 97 Grand Prix GT and get 19.7 MPG,

That sounds about average...I get about 19.8 now and its time to change plugs since I run 2 colder.With new plugs I get around 21/22 in town..same question...how long since the plugs,pcv and fuel filter have been changed???

~Larry~

i have 115,000 miles on it, and i have changed the spark plugs and wires not very long ago

i havent replaced pcv or fuel filter though

Sounds like that should be the next thing on your list and cant cost over 20 bucks for both of the parts....~Larry~

My car has 48k miles on it, they havent been replaced yet.

My car has 48k miles on it, they havent been replaced yet.

Sorry,what year is it??

Id at least replace the fuel filter and think about some ACDelco 41-101 spark plugs gapped at .058...the pcv can also just be sprayed out with some carb cleaner...but they dont cost much at all.

~Larry~

Alright, i'll see if i can get pcv and fuel filter, i'll let ya know what happens. Around what should my car get though? Just so i have an idea. Do these 2 things make a huge difference in gas mileage?

It should be,at the least 19mpg.

The fuel filter should be replaced once a year...I have seen alot of fuel filter's get cloged from crappy gas and one thing I never do is pull in the station and get gas when the truck is filling the tanks.I change mine every other oil change.For me thats every 6 months.

~Larry~

ok, i'll get the fuel filter and pcv asap, ...one more question, is the fuel filter hard to change?

Your fuel filter is the same as the 97/03 and should be located under the drivers side frame rail and some of these instructions may help you out.....~Larry~

Click here for instructions (http://www.pfyc.com/supportfiles/gasfilter/)


http://www.pfyc.com/store/graphics/new/gn3010.jpg

cool, thanks for your help

Anytime....hope that helps you out!

~Larry~

Larry,
Sounds like you got stuck in a "loop".
OK, I have a 1998 GTP. I'm getting 14.9 MPG. I change my plugs every 10,000 miles. Change oil every 2,000. And have changed fuel filter twice.
I never race the car.. wait a min. you know me. OK, I race it only twice a day. To work and home.
You know I'm only playing.
http://img.photobucket.com/albums/v425/kustomkid54/1998PontiacGrandPrixGTP001.jpg

Ok, here are the results after changing the fuel filter and pcv valver. I got 255 miles to my full tank right when the low fuel light came on, drove 10 more miles with the light on to a gas station and put some gas in. So 265 divided by 18 is 14.7 . Slightly better, but not near what i should get. Do u have any idea what else i might look for? .....i know for one thing it has a rought idle.....and when i come to a red light, make a complete stop, and it is idling around 900 rpms, about 10 seconds later, the engine idles down to about ~700 then when i take off it hesitates till it gets to about 1100 rpm, and after that it runs smooth.

Without the car being scaned,its hard to tell.Other parts that would cause bad gas mileage could be the O2 sensor since you have over 100,000 miles and also you could have a either a bad or dirty Mass air flow sensor....Just kind of guessing now.

~Larry~

hello;
wow!! I have a 1991 pontiac Grand Prix GT coupe, with a 3.1 liter engine
in cherry condition I might add.fully loaded . Im getting 25 plus MPG,city
and 34 mpg plus highway. This thing even has the on board computer in the dash. I just love this cruising machine. when I bought this car i was wondering how accurate these computers were in these cars, so i checked the milage on three tankfulls and i was astonished how accurate they are. there rite on as the MPG,s OOPS, I think im bragging again. or just babbling

Don :lol2: :biggrin:

hmmm, well can i get it scanned w/o a check engine light being on? ....i have some kind of scanner at vo-tech that i could use..maybe.

Most shops have a scan tool, that will not only check for codes but they are also able to run a diagnostic check so they can see different parameters of the car, to make sure they are preforming properly.With out that tool, it would be hit and miss for a mechanic.

~Larry~

I was getting 23mpg in Maryland with half city/highway driving. Moved to Las Vegas las year and it went down to 18. Installed a FWI last weekend and its gone down to 16.5. I would have thought that would make it go up a bit. It doesnt make sense to me. I'm gonna do the filter change since its never been done-56kmiles. And the pcv. I think the plugs are supposed to be good for 100k. The car runs great but it cost me $36 bucks to fill the tank last night.

Ok, here are the results after changing the fuel filter and pcv valver. I got 255 miles to my full tank right when the low fuel light came on, drove 10 more miles with the light on to a gas station and put some gas in. So 265 divided by 18 is 14.7 . Slightly better, but not near what i should get.

hmmm... 1) 95' grand prix only came with a 17 gallon tank. 2) When the light comes on,that probably leaves you with about 2 gallons left, give or take.

Get a full gas can and put it in your car, and when your gas gets low and the light comes on, hit ur trip and see how far you can go (just make sure it's not down a country road with a sign that says "next gas station 100 miles" :wink:) that will give you an idea of how much gas you have left and you can get an accurate calculation 265/17 puts you up to 15.59 and i bet you it's even more than that

ohh, i was almost positive the '95 came with 18 gallon, well thats a lil better, hehe. and i'll try that, theblurr87, i sure hope it's gettin more than im thinking. I'll also try to get it scanned somewhere, ....i can guarentee its some of the sensors have gone bad, im guessing throttle control and prolly the o2 sensors. W/e it is, i cant wait to get it fixed, tyvm for all the help guys, i'll update when i get more results

i'll update when i get more results

Thanks,id be interested to know what the problem is!

~Larry~

hmmm... 1) 95' grand prix only came with a 17 gallon tank. 2) When the light comes on,that probably leaves you with about 2 gallons left, give or take.



my 97 has a 17 gallon gas tank and when the light goes on theres about 4 gallons left in the tank. i took it right down to the bottom of the yellow zone and there was still 3 gallons left. the gas mileage, in the driver info thing-ma-jig, says i'm getting 21 mpg, but when i do the calc, in between fill-ups, i'm actually getting 25 mpg.
P.S. who ever was complaining about paying $36 for a fill-up, you need to come up to canada, about $2.60 for regular and about $2.90 for super. fill-up usually cost about 45-47 bucks.

I'm currently getting 20.1mpg

exchange rate akwe! probably about the same

Have you ever change the timing belt on your car. IF the timing belt is stretched, it will throw off the timing, which will cause knock. The ECM in turn retards timing to combat the knock, making your mileage crappy. If your car has over 100k, and you haven't changed it yet, you're due. Go to the bank and get a loan, cuz that job ain't cheap, but it needs to be done before you grenade your engine.

exchange rate akwe! probably about the same

that was with the exchange and everything. .86$ a liter( this was the price friday for regular) x 4 = 3.44$ a gallon canadian/ 1.21(us rate in canada) = 2.84$ a gallon us x 17 gallons(size of my 97 gp tank)= about 48 bucks. i think 93 octane is an extra 9 cents a liter or 36 cents a gallon. the funny part is that on monday the price will drop down to .75$ a liter and it will slowly climb back up during the week.

Question: My fuel filter is giving me problems while removing.... The nut on the fuel rail is almost striped, possibly by previous owner, and it looks really rusted.... any help with this problem? You dont think I should replace the entire fuel line down to the engine do you?

WD 40 the nut andvise grap the nut. You can always replace it. Go to Sears. They have a nut breaker that works really well. I thought it was a bolt. May be wrong.
Shouldn't be a reason to change fuel line. If it has that much dirt in it. Run the car, and replace filter again. Good luck
http://img.photobucket.com/albums/v425/kustomkid54/1998PontiacGrandPrixGTP001.jpg

they make a fuel line repair kit to replace the stripped out end. You can get them at any auto parts store for around $10-$15. The kits come with a short piece of repair line, the threaded o-ring fitting and a compression union. Put anti-sieze on the threads to keep it from happening again.

thanks... Ill give it a try....

How did I see fuel filter? Damn glasses.
http://img.photobucket.com/albums/v425/kustomkid54/1998PontiacGrandPrixGTP001.jpg

Oh hell yeah..... I purchased the fuel line repair kit, hacked off some of the old pipe, spliced on the new (with replacement filter) and let me tell you some of the changes..... A feel in some increased power, increase in sound (custom exhuast is deafening now, oh yeah) <doesnt make sense right?......Fuel mileage went from 13.1MPG...yeah 13.1! too 18.8mpg...according to DIC... one weird thing though....> my total mileage trip calculation went from 129mprt (miles per remaining tank) all the way to 212mprt.... and it really shifts around at least 20mprt at stops and go's...which it never did before....Thanks for the advice, my car REALLY needed the new fuel filter.....!