Cylinder 5 Misfire

Discussion in 'GM Powertrain' started by philosofy1, Aug 27, 2009.

  1. philosofy1

    philosofy1 Member

    OK, first I would like to start off by saying thanks to all those that have helped me with answers when I posted up questions.

    Now, on my 98 Chevy C1500 (350) I am getting a misfire code for cylinder 5. I am nearing the end of the work that I have done on this truck, I feel this is the only thing that is holding me back.

    The parts that I have replaced since I have inherited this truck:

    spark plugs
    ignition coil
    ignition module
    fuel pump
    fuel pressure regulator
    coolant temp sensor
    oil pump
    egr valve
    pcv valve
    O2 sensor (2x) (before cat)
    belt tensioner

    I highly doubt any of these can cause a misfire, but who knows? Also, what is the idle suppose to be set at? The idle jumps, but i'm pretty sure it's cause of the misfire, would adjusting the idle help?
    Please, please, please, if anyone have any good ideas or suggestion please share it, I"ve been waiting a long time to drive this truck.

  2. Z71_guy

    Z71_guy Epic Member 5+ Years 1000 Posts

    you may have a bad plug or wire try swapping the plug to another cylinder and see if the code follows if it does then you found your problem if it stays swap a wire and see what happens
  3. Jimmiee

    Jimmiee Epic Member 5+ Years 1000 Posts

    Looks like you have changed everything but the injector. ;)
  4. philosofy1

    philosofy1 Member

    I'm crossing my fingers that I don't have to replace them. I've ran out of money for this project so if it is, then it's going to have to wait.
  5. Z07

    Z07 Member

    Pay close attention to the routing for #5 and #7 plug wires. If they run parallel it is possible for #5 to induce a spark into #7 and that would be very early on its compression stroke. These wires should cross at 90 degree angles when needed and be seperated a bit when they have to run close to each other. For a test try taking wire #5 out of the looms and run it way away from the others.
  6. nightmanx1

    nightmanx1 New Member

    I have the same thing but #1 and the last time it was the intake gasket was blown out. I am going to start digging into mine tomorrow.
  7. grimreapersshadow

    grimreapersshadow Rockstar 100 Posts

    get yourself some starting fluid and spray the area where the intake meets the heads and if your rpm's go up like you just pressed on the pedal then you got an intake leak and need to do them lower gaskets
  8. philosofy1

    philosofy1 Member

    Thanks guys, I'm try this stuff out today!!!
  9. philosofy1

    philosofy1 Member

    I was short on time yesterday, so I only had time to do the wire situation, yeah that didn't work. So, I'm left trying to find a vaccum leak.
  10. jt_5.7

    jt_5.7 Rockstar

    i have a question is the miss consistent or is it random

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