94 olds vert Posted October 1, 2009 Report Share Posted October 1, 2009 3.4l v6- New Air filter K&N My mpg on my last tank was 18.18 mpg on average. On Premium 92. No highway driving. Drove with a lead foot. This last fill up was on just regular gas and I averaged 14.71 mpg. No highway driving. Drove like a grandma. Does the gas you get really affect your mpg that much? That is when I just bought the car and it had been sitting for the last 3 years so I filled it up with premium. Maybe now that the Highway ramp was just recently completed I can get on the e-way a little easier. Quote Link to comment Share on other sites More sharing options...
jake91 Posted October 1, 2009 Report Share Posted October 1, 2009 On Premium 92 you only need regular i ran premium it ran no different Does the gas you get really affect your mpg that much yes. but not by that much i check the pumps if i fill up with 15% ethonol gas i get 19 if i fill up with 10% ethonol gas i get 20. has it lost any power? if so mabey clogged cat if not bad fuel filter ? Quote Link to comment Share on other sites More sharing options...
94 olds vert Posted October 1, 2009 Author Report Share Posted October 1, 2009 Lol what cat? Mine was removed and straight piped. Bad fuel filter might be the problem. Quote Link to comment Share on other sites More sharing options...
jake91 Posted October 1, 2009 Report Share Posted October 1, 2009 okay then not the cat LOL im no mechanic but im leaning towards the fuel filter Quote Link to comment Share on other sites More sharing options...
94 olds vert Posted October 1, 2009 Author Report Share Posted October 1, 2009 I agree to that. Quote Link to comment Share on other sites More sharing options...
jake91 Posted October 1, 2009 Report Share Posted October 1, 2009 also once you do fix it dont worry about that lead foot when i drive like a grandma total city i get 19. if i drive with a lead foot i get 18. and if you can get on the highway it does wonder for fuel economy in these cars.with 50 miles on the high way and 150 city leadfoot miles and 50 grandma city miles i get around 21 Quote Link to comment Share on other sites More sharing options...
xtremerevolution Posted October 1, 2009 Report Share Posted October 1, 2009 14.7MPG is really pushing it there. That's pretty horrible. I drive my Bonneville very hard, and that's a 3800lb car with a 4.6L V8, and I never average below 16mpg. Quote Link to comment Share on other sites More sharing options...
jake91 Posted October 1, 2009 Report Share Posted October 1, 2009 i always thought the bonneville had the 5.3. huh learn something new everyday Quote Link to comment Share on other sites More sharing options...
94 olds vert Posted October 1, 2009 Author Report Share Posted October 1, 2009 i always thought the bonneville had the 5.3. huh learn something new everyday lol Quote Link to comment Share on other sites More sharing options...
xtremerevolution Posted October 1, 2009 Report Share Posted October 1, 2009 i always thought the bonneville had the 5.3. huh learn something new everyday The Bonneville GXP never had the 4.6L Northstar. It was the Grand Prix GXP that had the 5.3L. I would type out the suggestions, but this has to be the 4th MPG-related thread in the last 2 weeks, and the 2nd today. Just go back to the topics and find what other people have said to improve fuel economy. Quote Link to comment Share on other sites More sharing options...
jake91 Posted October 1, 2009 Report Share Posted October 1, 2009 since andrei is being a jerk today here is another thread http://www.w-body.com/forum/index.php?topic=81768.0 Quote Link to comment Share on other sites More sharing options...
carkhz316 Posted October 1, 2009 Report Share Posted October 1, 2009 The Bonneville GXP never had the 4.6L Northstar. It was the Grand Prix GXP that had the 5.3L. Wait? What? Pretty sure the Bonne has the 4.6 N* beings that yours has it Quote Link to comment Share on other sites More sharing options...
jeremy Posted October 1, 2009 Report Share Posted October 1, 2009 i always thought the bonneville had the 5.3. huh learn something new everyday if the Bonnie GXPs had a 5.3 in them there would be one in my driveway right now Quote Link to comment Share on other sites More sharing options...
5speedz34 Posted October 1, 2009 Report Share Posted October 1, 2009 On my 3.4 I drive pretty "spirited" and I average about 19 mixed on summer mix and 17-18 on winter mix. I know I need to replace my fuel filter and I wouldn't be surprised if I had a bad injector or IAC or something. Quote Link to comment Share on other sites More sharing options...
xtremerevolution Posted October 1, 2009 Report Share Posted October 1, 2009 The Bonneville GXP never had the 4.6L Northstar. It was the Grand Prix GXP that had the 5.3L. Wait? What? Pretty sure the Bonne has the 4.6 N* beings that yours has it Typo. I meant to say it never had the 5.3 and had the 4.6... Quote Link to comment Share on other sites More sharing options...
carkhz316 Posted October 1, 2009 Report Share Posted October 1, 2009 I thought that was probably it Quote Link to comment Share on other sites More sharing options...
jake91 Posted October 2, 2009 Report Share Posted October 2, 2009 x2 Quote Link to comment Share on other sites More sharing options...
1990lumina Posted October 2, 2009 Report Share Posted October 2, 2009 My Lumina used to get WAY WORSE mileage when running premium fuel vs. regular. I never paid extra for premium but a few years ago some stations ran out of regular so they were selling premium for the same price. Car got at least 150km less on one tank of fuel. Quote Link to comment Share on other sites More sharing options...
xtremerevolution Posted October 2, 2009 Report Share Posted October 2, 2009 My Lumina used to get WAY WORSE mileage when running premium fuel vs. regular. I never paid extra for premium but a few years ago some stations ran out of regular so they were selling premium for the same price. Car got at least 150km less on one tank of fuel. Makes sense. All higher octane does is make the fuel less prone to pre-detonation in higher compression/boosted engines. My regal ran like crap the only time I took it to the track with a full tank of premium. Bad decision. Ran a 16.1. After a tune-up I'll go back and try it again with regular fuel. Quote Link to comment Share on other sites More sharing options...
jake91 Posted October 2, 2009 Report Share Posted October 2, 2009 i ran premium in my car once i saw no difference what so ever Quote Link to comment Share on other sites More sharing options...
AWeb80 Posted October 2, 2009 Report Share Posted October 2, 2009 my 3850 lb Aurora gets 22-23 in town w/ the 3.5L LX-5....on 87 octane not too shabby. I think you have some work to do...or go another tank and double check your numbers Quote Link to comment Share on other sites More sharing options...
94 olds vert Posted October 2, 2009 Author Report Share Posted October 2, 2009 I filled it up and i will crunch the numbers later. When I run out of gas. Quote Link to comment Share on other sites More sharing options...
94GPGTP Posted October 2, 2009 Report Share Posted October 2, 2009 My experience.. I use Shell gas only around here in my area.. Its the only gas i trust if i let me car sit because it wont varnish as fast as others.. I really dont care what the pricce is for fuel if i need it i need it.. If you are getting gas from a gas station that you never heard of before and there are not many others out there most likely the gas is gunna be shit toward other gas stations that are more popular.. I run a mix of gas in my cars.. my DD 3100 i run 87 all day everyday but once in a while i run 93 and i get better mileage.. I put the same miles on the 93 as i do with 87.. I drive a total of 100 miles a day to work so im buring fuel like crazy.. i average 26 out of my 3100.. Now my GTP i run only 93.. The car loves it and i also average 26 when i drive it to work once every week.. I really havent ran less than 89 in any of my 3.4's because i notice the difference.. But now on with your car.. With that sudden of a drop in MPG I'd say its the fuel you put in the car.. A filter may or may not cause that sudden of a drop right away in MPG.. Usually the MPG's start to fall slowly.. But for the price of the filter i would change it for the heck of it.. If the line is rusty to the filter i would think twice about it.. It also could or could not be mechanical who knows until more problems await.. Quote Link to comment Share on other sites More sharing options...
94 olds vert Posted October 7, 2009 Author Report Share Posted October 7, 2009 So...I did the math and a jaw dropping 8 MPG actually less,I like to round. Now, I now I have a major problem, Checked air pressure in all of my tires. And they are all low. With all this cold weather my mpg has been dropping even more. Now the tire says (44 psi max) Does that mean 44 psi should be in each tire? My drive side rear tire had 13 psi in it. And probably less when I check it tomorrow. Other tires were in a range from 25-30 psi. Low tires=bad mpg. I think this could be the problem. Quote Link to comment Share on other sites More sharing options...
Night Fury Posted October 7, 2009 Report Share Posted October 7, 2009 Put 30-35 in them. Quote Link to comment Share on other sites More sharing options...
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