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  1. #1

    Default 99 GMC Suburban 260000miles Stubbles on accel.runs fine after engine heats up

    Truck has 5.7 vortec engine and when it first cranks up if you give it gas it stummbles or goes dead. It idles fine and after it runs for a few mins. it will accelorate with no problems. I have replaced o2 sensors, tsp sensor, heat temp sensor, air filter and fuel filter. I have ran sea foam through gas. We recently replace intake gasket. It has a ses code of P0420 any help would be greatly appreciated

  2. #2

    Default

    I asume a cracked distributer..I have the same and just ordered a billet one on the bay for 88 bucks , not the plastic one that is in it !!!!

    1996 Suburban K3500 SLT DUALLY
    1988 Camaro RS 383 stroker LT1
    1992 32' Aero-tek Race Boat, 600 CI BBC
    WE CAN STICK A DIESEL IN ANYTHING
    SPECIALIZED IN CUSTOM CONVERSIONS OF ANY KIND
    Scott:glasses:

  3. #3

    Default

    Quote Originally Posted by dirt2191 View Post
    Truck has 5.7 vortec engine and when it first cranks up if you give it gas it stummbles or goes dead. It idles fine and after it runs for a few mins. it will accelorate with no problems. I have replaced o2 sensors, tsp sensor, heat temp sensor, air filter and fuel filter. I have ran sea foam through gas. We recently replace intake gasket. It has a ses code of P0420 any help would be greatly appreciated
    A Code.....P0420.....is telling you that you that the Catalyst System Efficiency is below its Threshold....

    There are a number of items that could be causing this P0420 Code. ......The most common item is the catalytic converter itself is no longer functioning properly,

    The other likely item is the rear O2 (oxygen) sensor is no longer working properly,but as you have already re-placed them................Some of the other items to look at would include exhaust leaks,damaged exhaust pipes,damaged O2 sensor wiring/connectors and last a plugged catalytic converter.

    MIKE


    99"SILVERADO
    5.3 l 3.73 l G80
    BLACK BEAR CUSTOM TUNE
    SNUGTOP l COLORMATCH l KATZKIN










  4. #4

    Default

    Sorry, did not read the code part !!!!!

    1996 Suburban K3500 SLT DUALLY
    1988 Camaro RS 383 stroker LT1
    1992 32' Aero-tek Race Boat, 600 CI BBC
    WE CAN STICK A DIESEL IN ANYTHING
    SPECIALIZED IN CUSTOM CONVERSIONS OF ANY KIND
    Scott:glasses:

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