MISFIRE DETECTED #6 what do i need to do next!

Discussion in 'GM Powertrain' started by t_bone72183, Oct 10, 2010.

  1. t_bone72183

    t_bone72183 New Member

    I have a 05 silverado z71 4x4 with the 5.3 engine. I have a missing problem # 6 cylinder. I have changed plugs and wires and still missed on #6 cylinder. Changed #6 coil out. still missed. Thought plug was fouled out switched #5 to #6 cylinder. Still missed. Then switched injector and still missed. Checked the plug and it is gettin fire. Also compression is 135 on cylinder .So what is my problem. Suggestions are highly appreciative!l ​
  2. stephan

    stephan Rockstar 4 Years 5000 Posts

    Well only thing left that I can think of is a vacuum leak.

    Is #6 pulling any weight at all?

    How do you know it is #6? What have you done to localize this problem to #6 cyl?

    I ask because as you have been switching parts between cylinders how are you determining that the miss is still on #6 & is not following the plug or the injector to the other cylinder that you are switching it/them to?

    What is the compression on the "other" cylinders?
    Last edited: Oct 11, 2010
  3. t_bone72183

    t_bone72183 New Member

    I have a mechanic that is got a computer and it shows the misfires. And it is #6 only....compression on other cyliders is good. The other cylinders is shows zero misfires. It is a intermitten miss. And yes it pulls weight it mostly misses at idle. If you are rollin at a steady speed and try to give it the fuel. It will miss then too but it picks back up and goes.

    Someone mention quadgears in computer could be goin bad on 6...idk
  4. stephan

    stephan Rockstar 4 Years 5000 Posts

    Ok your mechanic has an ocilliscope that is showing the fireing lines of the voltage?
    Is that right? What does your mechanic say is wrong?
    Your mechanic is there and can see & test the engine, and see the results so I would go by what he says.
  5. Nails

    Nails New Member

    Had the same problem with my 2010 Sierra. It had a bad lifter.

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