5.7 odd cylinders missing

Discussion in 'Chevy Truck Talk & GM News' started by mutant5776, Feb 2, 2012.

  1. mutant5776

    mutant5776 New Member

    96 Suburban 5.7L vortec Has anyone heard of this engine missing on only the odd cylinders. Just had new injectors and spider up grade kit installed and is doing the same thing. Hook up to laptop and some times i have only a couple misses and other time i have a boat load. Does not miss at all on the even cylinders. Using the Palmer Scan XL program to get my information.
    Last edited by a moderator: Feb 2, 2012
  2. murdog94

    murdog94 Epic Member 5+ Years 5000 Posts

    When was the last time you did a tune up?
  3. mutant5776

    mutant5776 New Member

    last thursday
  4. murdog94

    murdog94 Epic Member 5+ Years 5000 Posts

    You did a new cap and rotor at that time? the reason i ask is they are junk and need to be changed more often than some people realize. Next if that has been dont time to look for a vacum leak, and check the fuel pressure to the injectors. 55-60PSI is the normal range.
  5. billnorman

    billnorman Rockstar 100 Posts

    Some 4.3's and 5'7's have distributor caps which place the same side plug wires on the same side of the distributor cap with internal jumpers, which can break down over time. Something to think about.
  6. MrShorty

    MrShorty Epic Member 5+ Years 1000 Posts

    Because of the way GM numbers cylinders, the odd cylinders are all on one side of the engine. Right now, I can't remember which side is odd and which is even (odd is the driver's side, isn't it?). Because the misfires seem to only occur on one bank, I'd be tempted to look at things that are different between the two banks. I doubt I can think of a complete list, but some examples:

    1) maybe O2 sensors. Put a scanner on it and look at both upstream O2 sensors. Is there a significant difference between the left and right sensor signals and/or fuel trims? I might swap the upstream sensors left/right to see if the misfires "follow" the O2 sensor. If the misfire folllows the sensor, that would be a pretty good indication that one of the sensors is bad.

    2) a compression test might be interesting to see if there is anything different between the two banks.

    3) Check condition of spark plugs. Are the odd banks showing signs of fouling (oil/coolant/fuel) that are not present on the even side?

    4) maybe the valve train is worn on one side

    Anyway, lots of different things, but I think I'd try to look and see what is going on on that one side of the engine that isn't happening on the other to help isolate the problem.

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