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rizer
04-27-2005, 08:02 PM
Hey guys, wondering what you guys are getting for miles on a full tank on the 3.4L

I replaced the fuel filter & PVC valve bout 3 months ago and with bout 5/8 highway driving, im only getting about 280 miles a tank with the 15 gallon tank. I think that averages out to be bout 17mpg. Car seems to be running fine, needs a valve job but sides that, nothing wrong.

I drive about 535 miles a week and its getting annoying paying 60 a week just for gas for a V6. What all could be wrong?

DixieGT
04-27-2005, 09:20 PM
I get about 320 miles to a tank roughly. That is not normal to be spending 60 a week on gas, even though the prices have sky rocketed. The best thing would probally be to take it somewhere and get it scanned for trouble codes like autozone or something. It could be a lot of things wrong.

andrewe77
04-27-2005, 09:43 PM
How do you know it needs a valve job?

I would replace the spark plugs and wires before I did anything else. That pretty much constitutes a tune-up for this car.

Braves299
04-27-2005, 09:43 PM
about 300 mixed hwy/cty

rizer
04-27-2005, 09:47 PM
man, never realized how much our cars really sucked with mpg. Was looking at my window sticker and it says 18 city and like 28 highway, I wish. Sucks when 5 bucks of gas gets me about 40 miles after adding from a empty tank

Already changed the spark plugs and wires. It needs a valve job because you can hear it until about 10 minutes of it warming up, even in the arizona heat.

andrewe77
04-27-2005, 09:50 PM
Valve noise is common on the 3400 and there's nothing wrong with the engine. Try a heavier oil.

How fast do you drive?

How are you measuring your MPG?

H.O. Driver
04-27-2005, 10:02 PM
replace the front o2 sensor if you haven't already or if you have more than 75k on it, if the sensor is bad the PCM will richen the crap out of it and you will get horrible mileage. The only other thing I can think of is that your cat might be clogged too. When I was stock I never got great mileage, but after just doing exhuast I was getting over 30mpg on the highway, even with my CAI, DHP, Headers, SLP I still get 30mph on the highway and 25.5 in the city.

2002GT
04-27-2005, 10:07 PM
i get like 260-300 ALL highway... my LIM is leaking if that matters?

Braves299
04-27-2005, 10:08 PM
^Yeah that sucks kind of. I usually can get 350 if it's all highway.

rizer
04-27-2005, 10:20 PM
Hrm, thanks for the tips. How can I tell if my cats clogged up? The exhaust is all new from the cat back so its still stock with 100k miles on it. Im in undercar right now at UTI so i can do that and the o2 sensor right in class.

As for oil, ive been using GTX high mileage for the past 30k miles.

AaronGAGT
04-27-2005, 11:22 PM
wow. this is making me wonder now. Im LUCKY to get 275... fuel filter, plugs and wires are 1.5 years old. My car has 100k+ miles and Im guessing the previous owner had never changed any O2 sensors... Looks like that might be my cause.

edit: Damn it. I would search... but you can search "O2" because its too short and "oxygen sensor" brings up 2 whole posts. Unrelated too.

I know one is by the cat... where is the other one? On the rear exhaust manifold somewhere? *sigh* im n00bie scum at this... where's the how to for replacement???

Panacea
04-28-2005, 06:12 AM
All city about 220-260 per tank. All Highway about 320-400 per tank. Mix about 240-300 per tank.

MPG, City, about 17-20mpg. Highway, 25-35mpg, mix, about 20-25mpg.

Joker694
04-28-2005, 06:17 AM
I drive about 535 miles a week and its getting annoying paying 60 a week just for gas for a V6. What all could be wrong?

maybe this has something to do with it. time to move man you drive too much

H.O. Driver
04-28-2005, 08:15 AM
Hrm, thanks for the tips. How can I tell if my cats clogged up? The exhaust is all new from the cat back so its still stock with 100k miles on it. Im in undercar right now at UTI so i can do that and the o2 sensor right in class.

As for oil, ive been using GTX high mileage for the past 30k miles.

You will notice a rotten egg smell when you get on the gas, or you will notice an inconsistant acceration and a little bit of a rough idle. If you have access to a scan tool a clogged cat will give you some KR, going from my clogged cat to a high flow I went from 12* of KR to 0 and from 16mpg to 27mpg the next week with the high flow.

The o2 sensor behind the cat is there to make sure the cat is working properly, doesn't do anything major at all. The 02 sensor that you want to look at is the front one, which is on the rear exhuast manifold. It easy to get at, just need a o2 sensor socket to make it easy to get a hold of, but will be a PITA to get out if its been in there for years.

DjSylentMystyk
04-28-2005, 09:38 AM
jesus... I'm sitting here happy with like 240 all the way down to E you guys are seriously getting that much?!

H.O. Driver
04-28-2005, 10:19 AM
jesus... I'm sitting here happy with like 240 all the way down to E you guys are seriously getting that much?!
Yes :) With DHP/ICCU bundle, WAI and Exhuast I saw a highest of 35mph on the highway with some racing in there too. Drove to Norwalk last spring, all highway, then did a few laps down the track and went through town. Went 350 miles and took just 10 gallons to fill it, I still don't beleive that one to this day.

Braves299
04-28-2005, 10:29 AM
jesus... I'm sitting here happy with like 240 all the way down to E you guys are seriously getting that much?!

Mine has 140K miles and I'm getting around 300 mixed.

OT: It's so weird seing somebody from the SAME town.

DjSylentMystyk
04-28-2005, 10:34 AM
I guess I need to be getting me some new exhaust then.... got to spend money to save money I guess.
OT 2.0
and yeah braves. There is another person here from derwood. apparently they live right down the street from me. And there is some kind of may mod madness or something at a local location... But whenever u get yo ase back from school we should meet up.

Braves299
04-28-2005, 10:35 AM
Sounds good

DjSylentMystyk
04-28-2005, 10:38 AM
But seriously 300 Miles? I thought our tanks were only like 12 gallons? even on E with the light on for like 30 miles I fill up with like 11.911 and a 30 dollar receipt. (damn beautiful red bitch and her only loving 93....)

Braves299
04-28-2005, 10:40 AM
But seriously 300 Miles? I thought our tanks were only like 12 gallons? even on E with the light on for like 30 miles I fill up with like 11.911 and a 30 dollar receipt. (damn beautiful red bitch and her only loving 93....)

Woah there's your problem! Why are you running 93? You only need 87. Also, we have 15 gallon tanks. And I've found that in my car at least, the light comes on wayyyy early. I can still drive another 30 miles usually.

DjSylentMystyk
04-28-2005, 10:47 AM
:scream: I have 1/8th the amount of miles on my car, its 2 years younger, and you STILL get better gas mileage than me.... Thats bull... :scream:

Braves299
04-28-2005, 10:50 AM
Start running 87. Your gas mileage is worse witht he higher octane fuels.

Joker694
04-28-2005, 10:51 AM
But seriously 300 Miles? I thought our tanks were only like 12 gallons? even on E with the light on for like 30 miles I fill up with like 11.911 and a 30 dollar receipt. (damn beautiful red bitch and her only loving 93....)

14.1 gallons to be exact

DjSylentMystyk
04-28-2005, 10:58 AM
I'll give it a go today. And we'll see what comes out next week. too bad my driving is all city...

Braves299
04-28-2005, 12:21 PM
^Best place to go is the Citco/7-11 on the corner of Redland Rd. and 355. I've found it to be one of the cheapest around, and my car seems to run a lot farther on their gas. Do NOT go to Exxon. For some reason, their gas sucks monkey balls, and sometimes I only get about 200 miles out of a tank when I fill up there. Also, if you see a truck that is delivering new fuel to the station, stay away from it. It's stirring up sediments and it's likely the gas will be crap since you're buying from the bottom of the tank.

DjSylentMystyk
04-28-2005, 12:29 PM
yeah, usually I go to free state (cheap skate) except when I don't have any cash on me. But I'll check out the good ol 7-11. Germantown had the cheapest prices there for a bit but they are just as high up as we are now. and I hear the sediment thing from my mom every time I buy gas. "God damit mike, stop letting your tank get past a 1/4. and don't go when they are refueling!"

XtremeGaGt00
04-28-2005, 12:29 PM
hey rizer...im goin to uti too, in illinois...im in undercar too...some weird ****...but anyways, i drive highway/around town kinda deal and i used to get like 170 to the tank, i replaced the plugs and put a magnaflow cat on and i now get 235...

AaronGAGT
04-28-2005, 01:43 PM
hey rizer...im goin to uti too, in illinois...im in undercar too...some weird ****...but anyways, i drive highway/around town kinda deal and i used to get like 170 to the tank, i replaced the plugs and put a magnaflow cat on and i now get 235...

wow. talk about awful gas mileage. ~13 MPG.... LOLOL gross! even though you're better now... its still bad. ~17.5 MPG? (dividing by 13 gal).

I drive my car like I stole it, all city driving and I get at LEAST 250 (which isnt too good). I'll see what changed when i put new o2 sensors in.

Braves299
04-28-2005, 01:44 PM
They're FIFTEEN gallon tanks.

Joker694
04-28-2005, 01:55 PM
my 2000 and my gf's 2002 say 14.1 in the manual

mekaleka
04-28-2005, 01:58 PM
20 city/28 highway.

Braves299
04-28-2005, 01:59 PM
my 2000 and my gf's 2002 say 14.1 in the manual


Really? Mine says 15. But it also says I have 180hp. lol

Joker694
04-28-2005, 02:10 PM
180 hp lol well they could have changed it. pontiac.com says 14 for the 2005 grand am so who knows

DrFabulous
04-28-2005, 02:36 PM
My 2001 says 14.2. Odd.

I get about 24-27 in the city, sometime up in the 35-37 range when driving long distances. Of course, I have the 2.4, so yea. lol

badboy2451
04-28-2005, 05:14 PM
im only gettin around 225 after filling up all the way(15 gallon tank) with highway/city mix ...WTF!!, i still need to replace the fuel filter and get my new plugs and wires in but i dont think that it is goin to help

AaronGAGT
04-28-2005, 05:19 PM
They're FIFTEEN gallon tanks.

um. my owner's manual says FOURTEEN POINT THREE.

badboy2451
04-28-2005, 05:22 PM
this has been covered before...different makes and models have different fuel tank sizes

AaronGAGT
04-28-2005, 05:23 PM
this has been covered before...different makes and models have different fuel tank sizes

it has also been covered why your gas mileage sucks...

steranko75
04-28-2005, 05:33 PM
I also commute for work - over 500 miles a week, usually more with additional travel for work - and I'm running about 28 miles per gallon, and doing the happy dance because I used to drive an Intrepid, and that was like 20 mpg

crazypontiac03
04-28-2005, 05:38 PM
I'm getting about 300-340 Depending on Traffic Flow. I drive mainly Highway. Something is diffently not right with ur car. I dont know what to tell you.

smokeybrown
04-28-2005, 05:40 PM
Well, I just bought my 01 gt w/ 30k on the odo, I am getting about 24 miles per gallon.
Smokey

badboy2451
04-28-2005, 06:03 PM
it has also been covered why your gas mileage sucks...


i dont remember me asking why mine sucked...just simply stated that it did

XtremeGaGt00
04-28-2005, 06:47 PM
yah, i drive mine like i stole it too, it dosent help i know...maybe ill try replacing the 02 sensors on both banks and see what happens, its gonna suck cause im drivin to lansing michigan from chicago, and i really dont wanna have to fill up twice on a 240 mile trip...

AaronGAGT
04-28-2005, 08:18 PM
i dont remember me asking why mine sucked...just simply stated that it did

weird. I dont remember you asking either! :violin

rizer
04-28-2005, 08:57 PM
Man, this thread took off since this morning, heh

When you guys said how to check the cat with the idle deal, theres times when i'll give it a little bit of gas as im starting it. It revs up, then almost stalls when it drops down from the first rev, then goes back up to bout 1500rpm for a second. Would that be some kinda sign?

Panacea
04-28-2005, 09:06 PM
They're FIFTEEN gallon tanks.
99's I believe were 15, the rest are 13-14 gallon tanks.

Panacea
04-28-2005, 09:08 PM
yah, i drive mine like i stole it too, it dosent help i know...maybe ill try replacing the 02 sensors on both banks and see what happens, its gonna suck cause im drivin to lansing michigan from chicago, and i really dont wanna have to fill up twice on a 240 mile trip...

Uhh, keep the RPM's down and you can make it there and back with at least a 1/4 of a tank. You'd think you'd be smart enough to tone your driving down a bit if you are worried about crappy gas mileage.

GrahamKracka
04-28-2005, 09:14 PM
i get around 280...all city driving

Bgonz22
04-28-2005, 09:48 PM
I get a constant 22 mpg... I think it's normal

jordanGT
04-28-2005, 09:53 PM
I'm getting close to 30: usually from 28-31 mpg: 90% highway. I was getting that with a dirty, dirty k&n filter and stock everything else. I cleaned out the filter and put in a new pcv valve and the mileage didn't change. I'm getting slightly less (I think more in the 27-28 mpg range) since I put my 18s back on, but I haven't actually done any calculations, just watching the odometer and gas gauge, which is far from precise.
My tip for saving gas: take it easy with the right foot. I've started driving the speed limit on the interstate (yeah; it's crazy) and pretty close to it everywhere else. I don't hot rod around. Aside from the good gas mileage, having a more relaxing commute is very nice. Keep your car tuned up and drive it a little easier and good gas mileage isn't unusual with these cars.

H.O. Driver
04-29-2005, 03:14 PM
yea, the drop in RPM like that might be do to too much back pressure (clogged cat) Have you noticed that the exhuast sounds different than it used to? Thats a way to tell too.

I just ran down the tank and filled it up today, put in 14.5 gallons and I had 380 miles on my tank. That was part city/racing and half highway driving. When I was on the highway I was toying around with a G6, they don't shift out of 2nd till 83mph if you manually shift, lol In matter of 20 miles we took them up to 110 about 5 times from 70mph rolls. Its my room mates G6 and we were on our way back from dinner. I still got 26miles per gallon and that included the 5 stop light runs I did before the highway

H.O. Driver
04-29-2005, 03:20 PM
Another thing mine did when I had a clogged cat was that when I would get in and fire it up it would raise the RPMs drop and stall out right away, I would give it some gas and it would go and bounce the idle some but it wouldn't stall again.

GAGTnut38
07-05-2005, 06:20 PM
Dudes i went to alabam earlier this year and ill tell ya what i was refueling at a quarter tank every 160-180 miles and still have to fill up every 160-180 miles .i refuel at a quarter tank cuz fuel pumps go bad if you run it to e everytime but i bet if ran to e i would only get like 200-210 miles to a freekin tank

ViperGTSR
07-05-2005, 06:36 PM
29mpg freeway, on 18s dont know how many mpt

2xPutt
07-06-2005, 05:50 AM
wow. talk about awful gas mileage. ~13 MPG.... LOLOL gross! even though you're better now... its still bad. ~17.5 MPG? (dividing by 13 gal).

I drive my car like I stole it, all city driving and I get at LEAST 250 (which isnt too good). I'll see what changed when i put new o2 sensors in.


damn, i sit here and am reading everyone's MPG posts, and am getting very upset about my car, lol.... i drive my car crazily, all city, and i am lucky if I meet 180 MPG.... ONE time, when I went from my house to some place in Indiana, i got to 240.... i think i really need to check up on everything, lol

2000GA
07-06-2005, 08:15 PM
I just got 356 miles on my last tank and put in 12.2 gallons for 29 mpg and I was kind of upset. I think it was from running the A/C all the time. Two weeks ago I got 35 mpg with straight highway driving with my V6 and 92k miles. You guys need to take it easy and start setting the cruise.

1hotgagt
07-07-2005, 08:59 AM
would a clogged cat give you unsteady RPMS and slow acceleration and terrible gas mileage? can i replace my stock one with a high flow one and match it up to stock exhaust?

freakydeaky
07-07-2005, 10:13 AM
the catalytic converter keeps your air to fuel ratio around the stoichiometric point (the ideal ratio), which keeps you from running too lean or too rich.... if yours is clogged, this would definately result in poor gas mileage....... here's a converter i found... it's not considered hi-flo cat... but here ya go... it will drop in to your stock exhaust------> magnaflow p/n# 53005

stanjk3
07-07-2005, 09:06 PM
Just another thing to check if you're getting crappy MPG - engine temp. Mine was running too low, would barely go above 1/4 in the winter, went as low as 16mpg.
Had the thermostat replaced a month ago and I'm back to my normal 21mpg. Of course I had to endure the usual BS from the dealer, though in the end I can't complain as it was covered by warranty.

I'm almost at 75K miles, when should I replace my O2 sensor??

smokeybrown
08-26-2008, 07:55 PM
back from the dead bitches. I am on my 3rd GTO now. What a pig.

hass
08-29-2008, 08:07 PM
Holy dead thread batman.
But anyway.

I got 29.1 mpg on my way to Cranberry Lake (from Middleport NY).
Was about 150 miles down the thruway ( @70mph) then the rest down highway roads... and really curvy roads, where my car got 80+ because I don't brake going down hills and stuff to save gas, rofl.
Also, the car was loaded probably the 2nd heaviest load I ever had... girlfriend + her sister and myself (her sister is a damn damn big girl, weighing more than my girlfriend and I combined) and tons of crap + subs and what not.

Then on the way home I did 80-85 down the thruway the whole way due to the girlfriend having a panic attack and we had to get home asap... Got 31.4mpg on the way back. (highest ever for me)

Tricks I use; Don't force the car in to shifting in to 3rd.
I speed up like an old granny.... Probably never getting the car above 2k RPM unless I'm turning (like making a right on red) and a car is coming up behind me faster than I thought and I have to hit the gas a little bit.

But I think the big one is not having the car shift in to 3rd. I probably went the whole way down the thruway only having the car shift in to 3rd maybe 2-3 times max, if that.
I also do the same thing when going up a hill, I'll let off the gas and let my speed drop down, often going quite a bit below the speed limit... but not letting it shift in to 3rd at high speed because the RPMs go wayyyy high and I assume it guzzles gas pretty bad.

I am however, running 93 gas + a DHP PCM.
The PCM isn't tuned for my car at all though.
Going to switch over to a CAI, new fuel filter, and get my car properly tuned and see what happens then with my mileage.
Usually I get about 27-28mpg though w/ mixed city/highway (no thruway).

nickofcourse
09-01-2008, 09:21 PM
nice mpg. pm pics of the sister. thanks. :3

hass
09-06-2008, 08:21 PM
nice mpg. pm pics of the sister. thanks. :3

chubby chaser? :P
I'll try to get some, lol.
I tried to show her sister to my mom but I couldn't find any pictures with her body in them at all in her house. All head shots, I was like well.. at least she knows she's big.
I'll dig through photo albums, because my mom still wants to see :P

duramax1031
09-18-2008, 10:47 PM
k this is my first post ON this site....my g/f has a 2001 grand am gt with 93k on it we have had it since 61k...lately she has been getting horrible gas mileage...she will use a quater of a tank just driving through town...prolly 3 miles with stop and go traffic....we used to get really good mileage...i just changed the plugs(2 weeks ago) and the wires around last year or so....the 02 sensor has never been touched to my knowledge or has the fuel filter...could it be the 02?im guessing it is....any advise would be helpful

duramax1031
09-19-2008, 08:53 AM
need help right now!!!!

Ajaxus
09-19-2008, 09:07 AM
when was the last time the fuel filter was changed? and also check the condition of the air filter on it. those would be the first two i'd check..although that mileage is gastly!

duramax1031
09-19-2008, 01:06 PM
i change the air filter every oil change.....i have a fuel filter in hand put i dont kno how to put it on and i dont think its ever been changed with 94k on it.....do u think it is the 02?...she says she can smell gas (not rotten egg smell) every now and then

duramax1031
09-28-2008, 10:22 PM
i just replaced the fuel filter and gas mileage isnt getting any better...maybe worse what do i do?....i went 80 miles on a quater tank on intersate going about 73 or so

gagt Mechanic
09-28-2008, 11:20 PM
if the fuel filter has never been changed with 94k and you just changed it, start saving up for a fuel pump, it will probably be going out soon, sorry.
Is the check eng light on/ ses. rotten egg smell can also be caused by poor gas quality, if you can, stick to the big 3, bp amaco, mobil, and shell. stay away from the cheep crap. pay the extra .02 cents a gallon. 02 sensors should turn on the check eng light. blocked cat may not.

changing fuel filter at high miles, as your fuel filter gets dirty, your pump has more resistance on it, after 94k there is a good amount of resistance. the pump gets used to it to an extent. new low resistance fuel filter will allow your pump to spin faster and burn up, seen it many times.

duramax1031
09-29-2008, 09:53 AM
k well im getting one for 30 bucks with 40 k on it...i dumped black stuff out of my filter...there is no rotten egg smell but she does smell gas every now and then which could mean o2 sensor...i got the car at 60k and i never changed teh filter until now which now has 94k on it or something...im first owner it was a lease car before me...i just checked the VIN and at 30 or 40k is said fuel pump module replacement?..car seems to be runing great except fuel milege...its throwing no codes are anything

WeibSunder
09-29-2008, 04:10 PM
<---16 gallon tank and I can get 247 miles before my fuel light comes on, when it pops on, you have 22 miles before it makes you walk. 17 mpg sucks.

silverbullet51
10-08-2008, 08:40 PM
When I first got the GAGT, I got about 215 miles on a tank in winter and 280 in summer.
So my fuel economy project began back in July 2006 and since then I:
- changed fuel filter (Fram)
- changed spark plugs (NGK Iridium IX)
- changed plug wires (Taylor Red 8mm Spriro Pro)
- replaced EGR valve
- replaced IAC valve
- thoroughly cleaned throttle body and intake ductwork
- replaced PCV valve
- ran seafoam several times
- even tried Amaco Ultra 93 octane gas (waste of money, I know. just wanted to see what 93 would do)
- might be something else i forgot to mention

Now before somebody asks why I replaced certain things such as the EGR and IAC, the EGR was badly rusted, clogged ports, and worn. Pretty sure it was going to fail soon eventually. On the IAC valve, the spring and pintle were stuck and worn- causing my ****ty idleing. No cleaner did the trick.

All in all, I now easily get 320 miles on a tank city/highway mix with at least a gallon left (I almost always fill up when the gas light comes on, and seldom drive past that point so don't blast me about fuel pump failure cuz I know the risks!) We'll see what winter does this time around

On a side note: I occasionally go to the E85 station and put E20 in cuz it's a little cheaper and my car seems to run better on it! Anything higher that 20% ethanol and you risk damage from running too lean. I'm not that stupid to put E85 in, however tempting it may be.

Hope this all helps somebody.

Mike Jung
10-08-2008, 10:19 PM
...I'm not that stupid to put E85 in, however tempting it may be...
I wonder how that guy is doing ?

lol