The Beast has a stu,stu, stutter! Help!!!

Discussion in 'Performance & Fuel' started by vncj96, Jun 30, 2010.

  1. vncj96

    vncj96 Epic Member 5+ Years 1000 Posts

    Sorry if this gets long winded.

    My suburban is having a random stutter at idle and upon take off from a stand still you can feel it bogging a tad (randomly as well). it is very intermittent and when it is happeining its not even either like on cycle with the firing of the spark plug. It has a new fuel pump, filter and the fuel pressure is solid. when sitting at a light or stopped with the foot on the break and only after it gets closer to operating temp there is a sputter, and the truck will shake like its gonna die but only for a split second. The tach will jump ever so slightly and you can hear a crackle/pop, like the ignitor on a gas stove/grill. It really only does it when the truck is in gear so its hard to check and see if the wires are arching or something, but also am beginnning to wonder if this is fuel injctector related. if i am steady on the gas the exhaust is fine but if I am rolling and I hammer it there is some black smoke out the pipe like it is running rich. Again leading me to believe there is an injector problem. I am gonna run some seafoam in the gas and through the brake booster line and see what happens. So if it is the injector how do I isolate it to figure out which one (would it be evident on the plug?) Or is it really a crap shoot, I have no SES/CEL either. Thanks in advance!!
  2. MrShorty

    MrShorty Epic Member 5+ Years 1000 Posts

    Even though the SES is off, I might pull codes anyway -- there may be pending codes that will help to isolate the problem.

    The crackle/pop makes me think of an ignition issue more than an injector issue. The injectors are buried inside the intake where any sound they would make would be muffled. Have you tried using a spray bottle to spray water mist around the wires/distributor/etc. to see if you can induce a spark leak?
  3. murdog94

    murdog94 Epic Member 5+ Years 5000 Posts

    Check the bushings in the Distributor.. They are plastic in the Vortecs, and the bushings go out.. That honestly sounds just like one that my buddy had a problem with at first then the stumble got worse.
    And as MrShorty said the injector assembly is buried under the upper intake. You might have a fuel pressure regulator problem or else possibly a torn injector line.. I dont know if you have seen what they look like but the spider assembly holds the injectors and they use plastic lines to route the fuel to the cyl.

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