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96 truck misfire issues

Discussion in 'Chevy Trucks' started by DareDog, Oct 23, 2013.

  1. DareDog

    DareDog PlowSite.com Addict
    Messages: 1,438

    1996 1500 5.0L, started yesterday morning as i was parking the truck was running really ruff and skipping. then went to leave last night and was still same but now check engine light was flashing. made it home and got code P0300 Misfire. does not say what one. checked the plugs and wires they were fine. what could it be?
     
    Last edited: Oct 23, 2013
  2. Wilnip

    Wilnip Senior Member
    Messages: 583

    How do you know the wires were fine? I'd replace wires first, then possibly the coil.
     
  3. dieselss

    dieselss PlowSite Fanatic
    Messages: 10,983

    When's the last time you changed the cap and rotor? And just b/c the wires look good don't mean they are
     
  4. kimber750

    kimber750 PlowSite Veteran
    Messages: 3,688

    Has the truck been sitting for awhile? If so could be bad fuel causing one of the poppets in the fuel injection to clog. Had this happen to my Blazer after sitting for awhile, some fresh fuel and injection cleaned cleared it up.

    Would start with first two responses then try this. Chevy coils have habit of suddenly going bad, especially in the rain.
     
  5. DareDog

    DareDog PlowSite.com Addict
    Messages: 1,438

    thinking now its cap and rotor. truck sat most of summer but i have been driving it past weeks and its been running great.
     
  6. DareDog

    DareDog PlowSite.com Addict
    Messages: 1,438

    check the wires by putting spark plug in to see if it gets spark and all of them did. now thinking it mite be coil cause spark was little yellow color not blue. plugs were replaced 20k ago.
     
  7. dieselss

    dieselss PlowSite Fanatic
    Messages: 10,983

    Did you ck the cap and rotor
     
  8. Wilnip

    Wilnip Senior Member
    Messages: 583

    when spark plug wires go bad they do not just stop working. They short out, they short to other plug wires or to the block itself. That's what causes the misfire. Just because they all have a spark and are conducting electricity does not mean they are good. You can get a halfway decent set of plug wires at the parts store fairly cheap. You may also want to see if they can test the coil. Iknow some they can, some they cant. A good tune up is where to start. Plugs, wires, cap and rotor.
     
    Last edited: Oct 23, 2013
  9. terrapro

    terrapro PlowSite Veteran
    from MI
    Messages: 3,878

    Try running the engine in the dark. If you see spark from the wires you are grounding. If not I would check the cap a d rotor next.
     
  10. 2COR517

    2COR517 PlowSite Fanatic
    Messages: 7,115

    Cap and rotor are notorious failure points on these engines.

    Has it been raining?

    Btw, making a spark across .050" in open atmosphere is completely different than making a spark in a pressurized combustion chamber.
     
  11. DareDog

    DareDog PlowSite.com Addict
    Messages: 1,438

    more diagnostic....cylinder 7 is cold and others are warm, not firing but it has spark but its not that bright. took plug out put it in the lawn mower and it has nice blue spark.
     
    Last edited: Oct 24, 2013
  12. Wilnip

    Wilnip Senior Member
    Messages: 583

    Just sell the truck. Several people gave you advice on what to do, including myself. You choose to continue to piss around and do nothing that was suggested to you.
     
  13. 2COR517

    2COR517 PlowSite Fanatic
    Messages: 7,115

    He can't sell the truck. We need the entertainment
     
  14. DareDog

    DareDog PlowSite.com Addict
    Messages: 1,438

    Ha, plus its the plow truck! Thanks for all the advice and help. I told my dad about it and he did not want to put the money in for new plugs and wires or cap rotor and that not be it. so he went to pick and pull place got wires,plugs, and rotor/cap, and a coil. hoping that fixes it.
     
  15. 2COR517

    2COR517 PlowSite Fanatic
    Messages: 7,115

    Nothing like junkyard tuneup parts
     
  16. dieselss

    dieselss PlowSite Fanatic
    Messages: 10,983

    Really. Are you joking. Yea that's just asking for failure in the near future. Why skimp on your tk that's easily going to make you back the 175.00 in tuneup parts well good luck. Hope they don't fail in the middle of a snow storm
     
  17. DareDog

    DareDog PlowSite.com Addict
    Messages: 1,438

    its true. also he gets brake pads there also! :eek:
     
  18. rofoth6

    rofoth6 Member
    from iowa
    Messages: 67

    Who needs brake pads when you have a 600 hundred pound plow on front.:laughing: