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Engine problems

Discussion in 'Dodge Dakota' started by Drache, Sep 14, 2015.

  1. Drache

    DracheMember

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    Ok I'm having a problem with a random miss in the number 6 cylinder on my 3.9L

    I've changed the injector (even swapped injectors on other cylinders), changed the spark plug (even swapped spark plugs on other cylinders), tested the spark plug wires, and changed the distributor cap.

    Now the weird thing is, the one mechanic I took it to couldn't figure out the problem. He said the random misfire only happens at idle. Not when actually driving the truck.

    What else could be causing the problem?
     
    Last edited: Sep 14, 2015
  2. 65 sporty

    65 sportyWell-Known Member

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    Ck for a vacuum leak
     
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    • Drache

      DracheMember

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      None could be found
       
    • kiwigtx

      kiwigtxInternational Mod Staff Member

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      Sounds like you've changed out the obvious stuff....I'm wondering if there is an issue with the valve train, or a carbon-ed-up valve.
      I had a serious miss on No.1 in my GTX years ago...it was a spark plug. Damn thing wouldn't let me go over about 40mph in top gear.
       
    • 65 sporty

      65 sportyWell-Known Member

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      I have never seen it on a 3.9 but you could have a broken valve spring
       
    • Drache

      DracheMember

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      Forgot to mention, compression is 100% the same in all six cylinders.
       
    • kiwigtx

      kiwigtxInternational Mod Staff Member

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      mmm....that's not leaving a lot of things to look at.
       
    • 7mopar

      7moparWell-Known Member

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      Random misfire can be caused by about anything that moves and can knock. Have solved it by replacing tierod ends. Time to start looking at the not so obvious.
       
    • Cranky1

      Cranky1Well-Known Member

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      Does the computer throw out any code? That's about the only other thing I can think of. Even if it doesn't produce any codes, it could be causing it. How about looking at all the connectors to it? I recently had to do some work on the bulkhead connector on my 95 due to corrosion. I also made a water deflector to keep the water from hitting it whenever the hood was opened plus the rubber deflector wasn't doing a good job either.
       
    • 440roadrunner

      440roadrunnerMember

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      How about the wiring to and or injector connector? I've seen these "noids" you can buy to hook to them for testing. Don't know about those ones..........

      Wiggle the connector while running, unhook it and see what difference........

      Do these have the bottom intake cover like the V8s?

      What does the plug look like? I still "lean" (pun intended) towards vacuum leak. Remember, they can leak from the valley, as well.
       
    • owlafaye

      owlafayeMember

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      Separate your plug wires with some old innertube.......you would be amazed how wires leak strange currents.
       
    • moe7404

      moe7404Member

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      check the throttle plates for carbon buildup. i have been having trouble withe my engine dieing at idle. in my search for a fix i found out that the plates should be closed at idle. and if you mod the throttle body to crack open the plates the computer will try to adjust for that. also some guys do a mod to the TPS by drilling the holes a little and rotating the TPS housing. there are some good posts on some other sites about dieing at idle that have a lot more info. also when starting the engine dont open the throttle plates. because the computer uses that as a " 0 " set point for running the engine.
       
    • 7mopar

      7moparWell-Known Member

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      Hope this was fixed long ago. Original post was Sept 2015.
       
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