Thread: Terrible Gas Mileage

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  1. #1 Terrible Gas Mileage 
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    I was wondering if anyone had any ideas on why I am getting terrible gas mileage. I used to get 18 when I was in town but right now my DIC is showing 14.7. It has steadly dropped the past few tanks of gas. My driving is mostly city but it is not very hilly and I am not running it very hard. Any ideas?
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  2. #2 Re: Terrible Gas Mileage 
    I live here. SyntheticShield's Avatar
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    This time of year, with the colder weather, thats not uncommon. Colder, denser air is going to cause the computer to call for more fuel to account for more air per same volume.
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  3. #3 Re: Terrible Gas Mileage 
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    Should it really drop that much though?
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  4. #4 Re: Terrible Gas Mileage 
    I live here. SyntheticShield's Avatar
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    2, 3, and sometimes 4 mpg is not unheard of. My Rodeo was getting 22 - 23 mpg in the summer, its down to around the low 19's now.

    Now, Im not saying something 'couldnt' be wrong, but what you are experiencing I would normally write off as normal winter time fuel economy unless I had long term fuel economy records that showed other wise. This is my first winter with the Rodeo so I dont know what it normally gets. When I first bought it, it barely and I mean barely got 17 mpg. Some work here and there and I got it up to 23 peak, but with my driving habits it leveled out around 22.5 or so.
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  5. #5 Re: Terrible Gas Mileage 
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    That must be why mine has also dropped 2-3 MPGs too.
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  6. #6 Re: Terrible Gas Mileage 
    GTX Level Member Freebeer187's Avatar
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    Me 2! Ive dropped about 2mpg... I like the cold air though

    How To: E-Brake Pwn
    2001 GTP. D/S Rotors * Custom Intake * DHP PCM *
    Looking For - 3" in DP with Cat. PM me if selling
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  7. #7 Re: Terrible Gas Mileage 
    GTP Level Member JoshMcMadMac's Avatar
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    Also remember that a lot of places start running 10% ethanol in the colder months, which hurts fuel economy.
    2000 NavyBlueMetallic GTP Coupe
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  8. #8 Re: Terrible Gas Mileage 
    I live here. SyntheticShield's Avatar
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    We've been on 10% ethanol, for the most part, there were a few hold outs since gas priced near $4/gal and that has not backed off any yet even with the lower prices.
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  9. #9 Re: Terrible Gas Mileage 
    GTX Level Member Toofastgs's Avatar
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    I just put 15 buxs of gas in went from 16-18 to 13 MPG.
    Combination of winter gas and 10% eth gas i used
    00' GTP 350/420 - Retired
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    Current - Lexus ES300
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  10. #10 Re: Terrible Gas Mileage 
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    Defiantly all the above are correct, Just like the old cars with a choke the newer cars need to run rich to warm up....And don't forget you are probably letting your car idle to warm up, which the computer will calculate as terrible gas mileage (0 mpg) and bring down the average. Ethanol does change seasonally in some states and provinces, this could easily be a factor.
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  11. #11 Re: Terrible Gas Mileage 
    SE Level Member 2001camaroB4C's Avatar
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    Quote Originally Posted by Toofastgs View Post
    I just put 15 buxs of gas in went from 16-18 to 13 MPG.
    Combination of winter gas and 10% eth gas i used
    Not sure about when you posted. But I have read that some gas companies have been having issues with bad fuel because we decreased the amount of fuel we use so much that it has been sitting too long. I dont have a source to back that up right now but Ill see if I can find one and post it. But if the fuel you are using is older then it should be then that could have a large effect on your mileage.
    2001 A4 Camaro B4C, 1.94 60ft - 8.48 1/8@84.13 - 13.17@104.29, should go faster with a better track and no ses light.
    And now a 98 Grand Prix
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  12. #12 Re: Terrible Gas Mileage 
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    yea Im getting low 13's right now too. I used to get 18-22 city. I just did a tune up and got 29 miles a gallon HWY, but 13 mpg city. wtf?
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  13. #13 Re: Terrible Gas Mileage 
    GT Level Member GPSims39's Avatar
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    yeah mine is down too, pretty bad, it does need a tune up so it could go up a bit but its def cause the engine uses more fuel to warm up and idling for 15 20 to get the car warm eats up a good amount too. My wifes Explorer was getting around 300 to the tank in the summer now at like 220 230 to the tank in this cold.

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  14. #14 Re: Terrible Gas Mileage 
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    I think I'm having the same problem. what all normally goes into a "tune up"? I've changed my plugs and wires, what else can you replace to help with mpg?
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  15. #15 Re: Terrible Gas Mileage 
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    well you can change your oil and filter, make sure your tires are at the correct psi, try using some seafoam it always helps clean the engine if not improve mileage so much. i just realized i have a nice intake manifold leak and thats where my loss may be coming from. Oh well, I didnt like having this extra money around the holidays anyway....
    2000 Pontiac Grand Prix GTP

    I love my 5.0, but a little civilized muscle is a good thing! Especially when it always runs and doesn't leave you stranded on the highway.....
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