Truck was misfiring, but then quit after driving for a bit

Discussion in '4X4 Truck Talk and Repairs' started by Seth, Aug 21, 2009.

  1. Seth

    Seth Active Member

    Messages:
    1,807
    State:
    Owensville, MO
    It did this one other time before. Went outside to go to work and the truck was idling VERY rough and had no power. Drove it down the road a little and it would hardly go and the flashing "Check Engine" light started signaling a misfire. Then all the sudden it came back and ran fine, but the check engine light was solid then. Scanning it shows a random misfire.

    It's only done this twice in the last year I've had it. Any idea's what it could be? I hate these intermittent problems, easier when it's just cut and dry broke. :angry:
     
  2. Rich.Carpenter

    Rich.Carpenter New Member

    Messages:
    135
    State:
    Indiana
    If it's a fuel-injected engine, sounds like a mass air flow sensor problem or possibly an injector going out.

    If it's an older engine, I've seen something as simple as a PCV valve cause that sort of problem.

    In either case, a dirty fuel filter can also cause that behavior. My van also showed a generic "misfire" error when I needed new plug wires. If it was wet when you noticed the problem (dew, rain, etc.) I'd start with new plug wires. Even if it wasn't, new plug wires are a cheap and easy way to help narrow down the problem.
     
    Last edited: Aug 21, 2009

  3. Seth

    Seth Active Member

    Messages:
    1,807
    State:
    Owensville, MO
    It's a 1999 5.3l silverado. The fuel filter was replaced 10 months ago and has about 8k miles on it so far. I do need to clean the MAF and TBI I'm sure since it's hard telling when that was ever done. Also did a tuneup on it about 8 months back.

    It has always had an intermittent check engine light for both banks running lean
     
  4. Seth

    Seth Active Member

    Messages:
    1,807
    State:
    Owensville, MO
    My buddy just called and said that the scanner showed a random misfire, but that cylinders 7 and 8 were misfiring the worse. The only other thing was a bad o2 sensor. He drove it a while, but it seemed to drive just fine and had plenty of power.

    Guess I'll replace that sensor and clean the MAF and throttle body and see what happens.
     
  5. smokey869

    smokey869 New Member

    Messages:
    966
    State:
    frederickt
    you more than likely need to replace the coils on thode 2 cylinders, its a pretty common problem and they are easy to change, they will come and
    go for a while before they totally croak lol, also check your harness for those 2 injectors closely have seen some harness failures also, good luck with it
     
  6. Mark J

    Mark J New Member

    Messages:
    9,407
    State:
    Four Oaks, NC
    You can't rule out a fuel pump either. They don't always just quit.
    Went through this several months back. Had it towed twice to a garage. Both times by the time they got it ran fine. Second time I told them to keep it for a week and run parts with it to put some miles on it.
    They didn't have a problem.

    I picked it up and drove it two days and it quit again.
    This time the mechanic drive out with his expensive portable computer nd fuel rail gauge. It was a bad fuel pump.

    It would run rough, put up the idiot light and finally just die.
     
  7. catfishfearme

    catfishfearme New Member

    Messages:
    717
    State:
    govecity,ohio
    It's a 1999 5.3l silverado, thats whats the mater,:eek:oooh: go mopar, DONT JUST DRIVE IT, RAM IT!! :big_smile::wink: sorry bud, couldnt stop my self,i wish you the best, good luck:cool2:
     
  8. 1mickymoo

    1mickymoo New Member

    Messages:
    378
    State:
    Edgerton, Kansas
    sounds to me like leaky fuel injectors. you said you need to clean the tbi, but, i am asuming you have 8 injectors, tbi is one or two injectors at the throttle body. (tb) get a fuel pressure guage at the parts store(loane program) hook it up and see if the pessure drops while sitting, if so, repressurize system and pull up the fuel rail, place clean paper under the injectors and see wich one if any is leaking.