Aftermarket parts and Tune
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This is a discussion on Aftermarket parts and Tune within the Tuning: Electronic Engine Management forums, part of the Tech & Modifying & General Repairs category; I've always heard that you can't just put on aftermarket performance parts without a tune. But I never knew why. ...

  1. #1
    Registered User MrManny's Avatar
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    Sep 2012
    Houston TX

    Aftermarket parts and Tune

    I've always heard that you can't just put on aftermarket performance parts without a tune. But I never knew why. Wouldnt like a cold air intake still get you colder air? Or wouldnt a bigger exhaust still free up flow? So what does the tune do? And what exactly is it you are tuning? I saw a vid that said it's because the stock tune tries to keep your pwr from increasing no matter what parts you add. Is this true?

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  3. #2
    Super Moderator (Actually a SuperSpy) SD_GR's Avatar
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    You are adjusting fuel, timing, and boost in order to use the aftermarket parts. The stock car has stock mapping, that accounts only for the authentic parts. Once you start changing them, the car needs to have a fuel/timing/boost map that is actually appropriate. This is a crude explanation.
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  4. #3
            MainFrame's Avatar
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    The main problem with aftermarket intakes is that it mess up the MAF sensor readings. If your MAF sensor is telling your car it's getting X amount of air, when in reality it's getting Y amount of air, bad things can happen. The tune has no way of knowing what kind of power the engine was making.. sounds like the person in said video is either trolling noobs, or they're an idiot.

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  6. #4
    Moderator Donkey's Avatar
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    Da boonies,Va
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    Aftermarket parts and Tune

    Also once you free up the exhaust the boost control system is no longer calibrated. Just as changing to a different intake can cause the stock MAF scaling to be uncalibrated.

    Sent from my magic banana
    Resident Adviser @ WTF Tuning, LLC
    2002 FORESTER S
    1998 FORESTER S

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