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Thread: Subaru Mileage Sucking

  1. #1
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    Default Subaru Mileage Sucking

    Vixen's 2002 subaru 2.0T automatic used to get low to mid 20's for MPG's. well it started getting worse mileage, stuttering when it started and being hard to start. I cleaned the MAF and now it starts easy enough, and runs fine.. didn't fix the mileage though...

    Replaced the spark plugs and added a turbo back exhaust and SPT intake .. Have not yet tuned it. but mileage hasn't really changed.

    I'm thinking it's possibly the oxygen sensor? ... the back one should not have any impact correct? So would have to be the front one.. but that may have been replaced last May ( one of them was)

    Fuel filter maybe?

    Looking for any subaru advise I can get. These cars are still foreign to me .. ( pun intended)

    Only 93 octane gas has been run exclusively of course.
    2001 Corvette - Heads, Cam, Intake, Full exhaust, Hotchkiss Swaybars, z06 brake ducts, SS brake pistons & Lines Etc. Lowered & Murdered out.
    2000 Trans AM WS6 - Forged Motor APS Twin Turbo Kit. Full Suspension & C5 brakes.... in pieces currently
    1998 Trans AM STS Turbo
    1997 Jeep Cherokee - when you just gotta go places other things won't take you.
    1995 Mercury Grand Marquis - ugly but comfortable

  2. #2
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    Default Re: Subaru Mileage Sucking

    I bet if it had one plug changed and not the other, the one that wasn't has taken a shit too.



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  3. #3
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    Default Subaru Mileage Sucking

    I'm gonna guess it gets better mpg without Steve driving...

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  4. #4
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    Default Re: Subaru Mileage Sucking

    Lmao. This could be the problem too... That is why the brakes needed upgraded.



    03' SSS, 98' T/A,84' Monte Carlo SS,08' Civic, 65' Malibu SS
    RNA Team #217
    Rally Appalachia 11': 7th, Day 3
    Rally Dixie 12': Top 20, Day 1; Top 10, Day 2; Fastest Time, Day 3. (But DQ for ticket)
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  5. #5
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    Default Subaru Mileage Sucking

    All 4 plugs were changed
    2001 Corvette - Heads, Cam, Intake, Full exhaust, Hotchkiss Swaybars, z06 brake ducts, SS brake pistons & Lines Etc. Lowered & Murdered out.
    2000 Trans AM WS6 - Forged Motor APS Twin Turbo Kit. Full Suspension & C5 brakes.... in pieces currently
    1998 Trans AM STS Turbo
    1997 Jeep Cherokee - when you just gotta go places other things won't take you.
    1995 Mercury Grand Marquis - ugly but comfortable

  6. #6
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    Default Re: Subaru Mileage Sucking

    Shit, I meant to put O2 sensor, not plug. Had a moment... And I wouldn't think the secondaries would do anymore than trip the dummy light if they were done.



    03' SSS, 98' T/A,84' Monte Carlo SS,08' Civic, 65' Malibu SS
    RNA Team #217
    Rally Appalachia 11': 7th, Day 3
    Rally Dixie 12': Top 20, Day 1; Top 10, Day 2; Fastest Time, Day 3. (But DQ for ticket)
    Penn Dutch Rally 14': Turtle Award!
    Mille Rally 14':We finished
    Penn Dutch Rally 15': 2ND OVERALL!


    www.elzaperformance.com

  7. #7
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    Default Re: Subaru Mileage Sucking

    does it sound like it has a miss?

  8. #8
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    Default Re: Subaru Mileage Sucking

    Could be a lazy front 02 sensor, vac leak, fuel filter. that would be what I would look into 1st.
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  9. #9
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    Default Subaru Mileage Sucking

    No miss.
    2001 Corvette - Heads, Cam, Intake, Full exhaust, Hotchkiss Swaybars, z06 brake ducts, SS brake pistons & Lines Etc. Lowered & Murdered out.
    2000 Trans AM WS6 - Forged Motor APS Twin Turbo Kit. Full Suspension & C5 brakes.... in pieces currently
    1998 Trans AM STS Turbo
    1997 Jeep Cherokee - when you just gotta go places other things won't take you.
    1995 Mercury Grand Marquis - ugly but comfortable

  10. #10
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    Default Re: Subaru Mileage Sucking

    Quote Originally Posted by rocketman442 View Post
    Could be a lazy front 02 sensor, vac leak, fuel filter. that would be what I would look into 1st.
    This.... Didn't you add a downpipe also? If so could be tune as i don't think suby ecu's are learning ones.
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  11. #11
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    Default Re: Subaru Mileage Sucking

    MAF or MAP car?
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  12. #12
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    Default Subaru Mileage Sucking

    It was doing this before the turbo back exhaust.. When it was completely stock...

    It has a Maf should also have a MAP too.
    2001 Corvette - Heads, Cam, Intake, Full exhaust, Hotchkiss Swaybars, z06 brake ducts, SS brake pistons & Lines Etc. Lowered & Murdered out.
    2000 Trans AM WS6 - Forged Motor APS Twin Turbo Kit. Full Suspension & C5 brakes.... in pieces currently
    1998 Trans AM STS Turbo
    1997 Jeep Cherokee - when you just gotta go places other things won't take you.
    1995 Mercury Grand Marquis - ugly but comfortable

  13. #13
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    Default Re: Subaru Mileage Sucking

    I would still go with what rocketman said..
    09 Sonata (My DD)
    92 C1500 ( Winter Beater/ Hauler)


    07accord - "I want to be a nittany lion!"
    "I'm pretty sure I have no fam. in South Jersey.Real mullet fairing people don't have spray tans." Levilz


  14. #14
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    Default Re: Subaru Mileage Sucking

    Mine did the same thing and it turned out to be the MAF...let us know what you find out after trying rocketmans suggestions. I'm not much of a Subie guy, but cars with a MAF seem to be touchy over the later MAP only cars.
    2003 Azure Blue Mach 1
    2007 Jeep Grand Cherokee SRT8
    1989 Mustang LX Hatchback (Soon Up For Sale)

  15. #15
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    Default Re: Subaru Mileage Sucking

    Yeah +1 on your cleaning the MAF. Our '96 started doing that, and cleaning the MAF helped for about a week, then it took a dump. After new MAF, it gets better mileage than ever. So be on the lookout.

  16. #16
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    Default Re: Subaru Mileage Sucking

    they run horribly with vac leaks so check all your hoses etc. idk if it has a boost gauge but your vac should set right at -20 inches o mercury.
    "If you no longer go for a gap that exists, then you are no longer a racing driver" -Ayrton Senna
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