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Backfires when giving it gas

Discussion in '3rd Gen 4Runners (1996-2002)' started by Whaley9412, Dec 25, 2020.

  1. Dec 25, 2020 at 8:01 PM
    #1
    Whaley9412

    #1
    Whaley9412 [OP] New Member

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    When I start my 1998 4runner it starts and runs just fine. When you push the gas it will rev all the way out. After about 2 mins running it stays idling just fine but WHEN I GIVE IT GAS it won't rev past 2000rpm. Starts bogging down and back firing what do you guys think the issue is??

    I've tried fuel treatment and let's it run 1/4 the fuel it then refilled it. So far
     
    Whaley9412, Dec 25, 2020
    #1
  2. Dec 26, 2020 at 12:33 AM
    #2
    Trekker

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    Trekker Regular Member

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    Welcome. What engine does it have?
     
    Trekker, Dec 26, 2020
    #2
  3. Dec 26, 2020 at 6:18 AM
    #3
    Ahdofu

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    Ahdofu New Member

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    My first reaction is to attach an OBD scanner and lookup the diagnostic messages. Have you tried it yet?
     
    Ahdofu, Dec 26, 2020
    #3
  4. Dec 28, 2020 at 7:48 AM
    #4
    negusm

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    negusm New Member

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    Yeah, check for codes.

    With those kind of symptoms maybe the TPS has gone bad?...the ECU doesn't know where the throttle is? Is there a motor in the Throttle body like on the 2001-2002 that could go bad?

    Fuel cleaner isn't going to anything. Something is definitely broken. Cleaning the throttle body might help it, but I think you have to remove that to do a thorough job.

    I would also try the carb cleaner trick to find leaking vacuum hoses. Vacuum hose leaks usually cause bad idle and you say that's not the case. I don't know if a vacuum leak could cause the revving out.

    Please post back with what you find.
     
    negusm, Dec 28, 2020
    #4
  5. Jan 16, 2021 at 1:14 AM
    #5
    Ambush

    #5
    Ambush New Member

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    MAF - Mass Air Flow sensor. Get some MAF cleaner (yes do not use any other cleaner). Let it dry for a few hours then reinstall. The ECU is not keeping up with idle/throttle while it is running. Yup TPS should be checked as well. :)
     
    Ambush, Jan 16, 2021
    #5
  6. Jan 29, 2021 at 3:05 PM
    #6
    RoxToy00

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    RoxToy00 New Member

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    none
    my bet is a clogged cat converter.
     
    RoxToy00, Jan 29, 2021
    #6
  7. Feb 1, 2021 at 1:10 PM
    #7
    treyus30

    #7
    treyus30 New Member

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    treyus30, Feb 1, 2021
    #7
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