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1999 4Runner slow revving and loss of power

Discussion in '3rd Gen 4Runners (1996-2002)' started by pocah99, Jun 23, 2023.

  1. Jun 23, 2023 at 9:30 PM
    #1
    pocah99

    pocah99 [OP] New Member

    Joined:
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    Male
    Colorado
    Vehicle:
    1999 4Runner SR5
    Hello everyone,

    I recently bought a 99 4Runner SR5 and have been trying to figure out a power loss issue. I have cleaned the MAF with proper cleaner, replaced the TPS, and tried taking out the front O2 sensor to allow more flow before the cat, to see if the cat was clogged. I am not sure what to try next, it has me a bit lost. It starts and idles no problem, but you need to stay on the pedal for it to rev up, it is very slow revving. It doesn't stumble either. It drives fine besides the slow revving/power loss issue. There is no restriction on air flow, and exhaust seems to be fine as well too. The CEL is not on. Does anyone have any ideas or suggestions on what the issue could be?
    Thank you all.
     
  2. Jun 24, 2023 at 5:23 AM
    #2
    Ahdofu

    Ahdofu New Member

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    Matt
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    1997 4Runner SR5, V6, Auto, 4WD
    Any OBD codes?
     
  3. Jun 24, 2023 at 7:56 AM
    #3
    Rob41

    Rob41 Veteran

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    Northern Michigan
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    Magnuson Supercharger, CSF Performance Radiator, Eibach Pro-Truck Series 2R suspension, SCS Ray10 Bronze Wheels, Pedal Monster, TRD Pro Grill, TRD Pro Roof Rack
    How's your fuel filter?
     
  4. Jun 24, 2023 at 8:02 AM
    #4
    JET4

    JET4 Old Member

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    welcome, fuel filter
     
  5. Jun 25, 2023 at 8:40 PM
    #5
    negusm

    negusm New Member

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    You should still check the cat. Measure front and back temperatures. That little hole for the O2 won't help much for air flow. You'd have to disconnect the exhaust pipe entirely.

    Also, if no codes, it may be a bad fuel pump.
     
  6. Jul 1, 2023 at 6:58 PM
    #6
    pocah99

    pocah99 [OP] New Member

    Joined:
    Jun 23, 2023
    Member:
    #33573
    Messages:
    2
    Gender:
    Male
    Colorado
    Vehicle:
    1999 4Runner SR5
    The muffler needed to be replaced anyway, so I cut it off and was able to see that the cat looks brand new inside as well. No restrictions on the exhaust and still having the power issue. I also replaced the fuel filter, that didn't do it. The timing marks on the cam gears seem to line up fine as well. No OBD codes being thrown, and all the stats on fuel trims, and o2 sensor voltages check out as well. Does anyone have any ideas?
     

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