Thread: Horrible Fuel Mileage

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  1. #1 Horrible Fuel Mileage 
    GT Level Member TheDarkAngel's Avatar
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    I know I do a lot of town driving and that's horrible for mileage, but I get 15 MPG driving with a very light pedal. Last tank included about 100 miles of highway as well, and still came out at about 14.6. I'm thinking about changing the spark plugs, wires, and possibly a fuel filter. Anyone have any helpful opinions? The engine has 156k on it, N/A 3.8.
    First car- 1999 Buick Regal LS (Sold)
    Current ride- 2000 Grand Prix GT (The Dark Angel) DIY Intake, flipped bushings, visual stuffs, lowered on Eibachs, Topswap loading...........
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  2. #2 Re: Horrible Fuel Mileage 
    Turbo is the way to go. Fivefingerdeathpunch's Avatar
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    Clean the MAF.
    New iriduim plugs and new wires.
    New air filter.
    Clean the Throttle body too.
    Run some injector cleaner.


    Might help get some back, but these cars tend to eat gas in the city. I drive 95% city, and even in the summer I only get 16ish.

    SMGPFC Member #1
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  3. #3 Re: Horrible Fuel Mileage 
    GT Level Member TheDarkAngel's Avatar
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    Ok, that's mostly what I was expecting to hear. Still tho, 14.6 is horrible for a V6.
    First car- 1999 Buick Regal LS (Sold)
    Current ride- 2000 Grand Prix GT (The Dark Angel) DIY Intake, flipped bushings, visual stuffs, lowered on Eibachs, Topswap loading...........
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  4. #4 Re: Horrible Fuel Mileage 
    I live here. stealthee's Avatar
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    Driving around town kills mileage. If I only drive back and forth to work I get 23 mpg. If I do any running in town It drops to 19 mpg and that is with most of my driving being on the highway/bypass. You might see some improvement, but don't expect it to be major.

    Also, are you actually calculating mileage, or basing it just off of the DIC?


    2011 Mitsubishi Lancer GTS - DD mode
    1991 Mitsubishi 3000GT - Many mods to come
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  5. #5 Re: Horrible Fuel Mileage 
    I live here. ericspecullaas's Avatar
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    DIC lies to ya. its best check at fill up with your own math.
    im a cookie again yay me
    Quote Originally Posted by Bio248 View Post
    please learn to forum better.
    ^^new favorite quote
    Quote Originally Posted by Kilroy View Post
    It is a type of spiced shortcrust biscuit.
    only one person looked it up lol
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  6. #6 Re: Horrible Fuel Mileage 
    I live here. stealthee's Avatar
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    Quote Originally Posted by ericspecullaas View Post
    DIC lies to ya. its best check at fill up with your own math.
    Yeah that is why I asked him. Mine is never right. On one trip DIC showed 25.3 mpg and when I did the math I got 28.5. Weekly flll-ups are off by anywhere from .5 to 1 mpg.


    2011 Mitsubishi Lancer GTS - DD mode
    1991 Mitsubishi 3000GT - Many mods to come
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  7. #7 Re: Horrible Fuel Mileage 
    I live here. ericspecullaas's Avatar
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    Question stealthee. do you have to have the last word on everything lol kidding
    im a cookie again yay me
    Quote Originally Posted by Bio248 View Post
    please learn to forum better.
    ^^new favorite quote
    Quote Originally Posted by Kilroy View Post
    It is a type of spiced shortcrust biscuit.
    only one person looked it up lol
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  8. #8 Re: Horrible Fuel Mileage 
    I live here. stealthee's Avatar
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    No, I'm just bored.

    LOL


    2011 Mitsubishi Lancer GTS - DD mode
    1991 Mitsubishi 3000GT - Many mods to come
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  9. #9 Re: Horrible Fuel Mileage 
    I live here. ericspecullaas's Avatar
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    then get some more beer.
    im a cookie again yay me
    Quote Originally Posted by Bio248 View Post
    please learn to forum better.
    ^^new favorite quote
    Quote Originally Posted by Kilroy View Post
    It is a type of spiced shortcrust biscuit.
    only one person looked it up lol
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  10. #10 Re: Horrible Fuel Mileage 
    GT Level Member Madness's Avatar
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    New Iowa gas blends?, heard it is not so good
    Favorite Quote: You can't fix stupid!!


    http://www.youtube.com/watch?v=0gxKStPXyn8
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  11. #11 Re: Horrible Fuel Mileage 
    GTP Level Member LeadfootCJ7's Avatar
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    What mileage do you normally get?
    2007 Grand Prix GXP;2002 Camaro Z28 - tune, CAI, and exhaust
    2006 GMC 2500HD - ATS high flow manifolds and uppipes, turbo back exhaust, blocked EGR, Denali headlights, Reflexxion Cown Hood
    1994 Olds Cutlass Supreme 2 door
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  12. #12 Re: Horrible Fuel Mileage 
    GTX Level Member loopy smurf's Avatar
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    Check your tire pressure too...
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  13. #13 Re: Horrible Fuel Mileage 
    Turbo is the way to go. REDCRAPGP's Avatar
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    Tune up time
    Squirrels are my engine. I need a Ford Regal
    04 Comp G.
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  14. #14 Re: Horrible Fuel Mileage 
    SE Level Member fromne's Avatar
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    Kind of a long shot but if you dont have success with anything else, make sure your cats aren't clogged. This happened to me and it took a month or so of crap mpgs and 16 seconds to 60 (I got bored and timed it) before I took it in and found out I needed a new cat. And I only had 90k on it then
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  15. #15 Re: Horrible Fuel Mileage 
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    I'm having the same issue with my 2000 GT. Crap-ass fuel economy. got 21MPG today on the way in, all highway. I have the trip computer, and find that the 'gallons used' value is actually bang on correct, usually within .25 gallons based on filling up and comparing to the value on the computer.

    This car should be able to get 25-28 on the highway.

    Planning to do plugs and wires. But I really doubt this will do anything. Ran seafoam through it when I got it, and there was no carbon buildup to speak of.

    Only other issue is my thermostat. It seems to run a little cool, so I am thinking the thermostat is stuck open ,and casueing the engine to run too cool. In winter it would obvioulsy be worse.
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