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  1. #1
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    Default Very lean but only sometimes...

    Hello, everybody! I just started piecing together some light mods on my 1997 GTP, but every once in a while, the SES light will come on. The code is for a system lean condition, but it clears its self after a few days. I checked the fuel trims at WOT and they are right around 0, but when I'm cruising they go to 16. Is this supposed to happen, or should I get a smoke test done?
    Last edited by codyswanson4; 1 Week Ago at 10:03 AM. Reason: positive ft

  2. #2
    Turbo is the way to go. Fivefingerdeathpunch's Avatar
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    Default Re: Very lean but only sometimes...

    Have you cleaned the MAF lately?

    Negative trims like -16 means it's overally rich, a smoke test won't show you something there. a Postive fuel trim of +16 would mean it's trying to add fuel because it's lean.

    I'd suspect a dirty MAF sensor or leaking fuel injector if the trims are always negative on a factory calibration.

    SMGPFC Member #1

  3. #3
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    Default Re: Very lean but only sometimes...

    whoops, sorry, the trims are in the positive direction, I just went out to double check :P I just replaced the MAF, too.

  4. #4
    GrandPrix Junkie SgtMarshal's Avatar
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    Default Re: Very lean but only sometimes...

    usually there is a vacuum leak when the fuel trims to positive. a misfire will make the fuel trims go lean as well.

  5. #5
    Donating Users industrialfish's Avatar
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    Default Re: Very lean but only sometimes...

    Quote Originally Posted by SgtMarshal View Post
    usually there is a vacuum leak when the fuel trims to positive. a misfire will make the fuel trims go lean as well.
    I'd second that. Sounds like vacuum leak unless you are running e85 without a tune.
    2005 GTP - Graystone Metallic|SPO grills&spoiler/SE lip/Carbon Fiber INFERNO hood
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    33mm Dorman + Addco rear sway|Drilled/slotted rotors|Plasti-dip 17" QP2 at +27 offset

  6. #6
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    Default Re: Very lean but only sometimes...

    Check vacuum lines.

    With it being a 97, I'm sure literally everything is dry rotted.

    Replace all of those and do the intake gaskets as well. Could be those, too.
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