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CEL code P0171 now a low idle...exhause leak? raise the cat?

Discussion in '4 Cylinder' started by 98tacogrande, Jun 1, 2009.

  1. Jun 1, 2009 at 5:16 PM
    #1
    98tacogrande

    98tacogrande [OP] Active Member

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    Hey guys

    need some help here

    98 taco 2.4l auto 125k miles

    Few weeks ago i popped a P0420 code with no noticeable side affects

    now i popped a P0171

    When i start the truck it goes to a high idle...1500 rpm

    When truck gets to operating temp it drops down to a low...500 rpm

    dont think its the MAF i cleaned it really good

    My truck is low low low and i scrape the cat heat shield like everyday

    Im thinking i may have an exhaust leak

    How bad could it be?

    If i need to have exhause work done i was thinking about raising the cat. Anyone ever done this or know how difficult it would be?

    Appreciate any help (CT is pretty much dead;))
     
  2. Jun 1, 2009 at 5:31 PM
    #2
    chris4x4

    chris4x4 With sufficient thrust, pigs fly just fine. Thor

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    Have you checked for any vacuume leaks? Is the MAF connected propperly with no leaks?
     
  3. Jun 1, 2009 at 5:32 PM
    #3
    chris4x4

    chris4x4 With sufficient thrust, pigs fly just fine. Thor

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    For the P0420:


    A code P0420 may mean that one or more of the following has happened:
    • Leaded fuel was used where unleaded was called for
    • An oxygen sensor is not reading (functioning) properly
    • The engine coolant temperature sensor is not working properly
    • Damaged or leaking exhaust manifold / catalytic converter / exhaust pipe
    • Retarded spark timing
    • The oxygen sensors in front and behind the converter are reporting too similar of readings
    Possible Solutions


    Some suggested steps for troubleshooting a P0420 code include:
    • Check for exhaust leaks at the manifold, pipes, catalytic converter. Repair as required.
    • Use a scope to diagnose the oxygen sensor operation (Tip: The oxygen sensor in front of the catalytic converter normally has a fluctuating waveform. The waveform of the sensor behind the converter should be more steady).
    • Inspect the downstream heated oxygen sensor (HO2), replace if necessary
    • Replace the catalytic converter
     
  4. Jun 1, 2009 at 6:01 PM
    #4
    98tacogrande

    98tacogrande [OP] Active Member

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    when i cleaned the MAF (it wasne even dirty...stock airbox) everything looked good and tight. Vaccum leaks i would hear something weird right?

    Im concerned about my high idle at startup and low idle at operating temp.

    If its an exhause leak, could that mean that my exhaust manifold may be cracked at the joint or where it connects to the cat?

    My trucks pretty low but im gonna take a look right now to see if i can see any carbon pointing to an exhause leak.

    I do have an appointment at a shop tomorrow morning.
     
  5. Jun 1, 2009 at 6:17 PM
    #5
    98tacogrande

    98tacogrande [OP] Active Member

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    hate to pay $60 or whatever to have a shop look at it if i can figure it out.

    Pice are worth a 1000 words...

    first pic is intake of cat i think it ok...

    [​IMG]

    next 2 pics are of exhaust of cat. Notice a two tiny carbon spots? Could this be the problem?

    [​IMG]


    [​IMG]
     
  6. Jun 1, 2009 at 6:23 PM
    #6
    chris4x4

    chris4x4 With sufficient thrust, pigs fly just fine. Thor

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    Pics dont look bad.....I would check for a vacuum leak someplace.
     
  7. Jun 1, 2009 at 7:46 PM
    #7
    98tacogrande

    98tacogrande [OP] Active Member

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    i think i just found the problem i hope

    i reconected the hose, went to AutoZone to have the CEL cleared, and drove taco around and it seems to have fixed the problem. Higher idle now.:)

    hose line to power steering must have worked itself loose.

    [​IMG]
     
  8. Jun 1, 2009 at 7:47 PM
    #8
    chris4x4

    chris4x4 With sufficient thrust, pigs fly just fine. Thor

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    That was it! Glad you got it taken care of.
     
  9. Jun 1, 2009 at 7:51 PM
    #9
    98tacogrande

    98tacogrande [OP] Active Member

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    thanks for the help man!!

    now i aint gotta pay someone $60 just to take a look haha
     
  10. Jun 1, 2009 at 9:31 PM
    #10
    chris4x4

    chris4x4 With sufficient thrust, pigs fly just fine. Thor

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    4.10 gears, sliders, and lots of buttons.
    ANytime! :)
     
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