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Misfire

Discussion in 'General Jeep Discussion' started by Jeeper79, Sep 26, 2017.

  1. Sep 26, 2017 at 2:41 PM
    #1
    Jeeper79

    Jeeper79 [OP] Member

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    Sometimes the jeep misfires and sometimes it does not. I changed spark plugs, wires and coil plug. I did put in 5w 30 instead of 5w 20 before a trip to Maine. Did not know if that mattered. That was when the problem occurred. Also put in injector cleaner before the trip.
     
  2. Sep 26, 2017 at 2:52 PM
    #2
    Bob

    Bob Well-Known Member Moderator

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    What type of Jeep do you have exactly?
     
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  3. Sep 26, 2017 at 3:25 PM
    #3
    aggrex

    aggrex Well-Known Member

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    Welcome! Highly doubtful oil viscosity causing the misfire. More likely a ignition issue with either the wires or ignition coil that you stated have been changed. Check whether your wires were routed properly or incurred some damage from hot surfaces. Try the simple stuff first like listening for electrical arcs etc.
     
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  4. Sep 26, 2017 at 6:01 PM
    #4
    chris4x4

    chris4x4 With sufficient thrust, pigs fly just fine Moderator

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    Welcome! Can you give more info on your Jeep?
     
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  5. Sep 26, 2017 at 6:26 PM
    #5
    JKBob 25

    JKBob 25 Well-Known Member

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    Welcome to the forum Jeeper79. Oil viscosity would not cause a misfire. I Agreel with Aggrex. Look at your ignition and coil wires. Also as Aggrex stated. Arcing. If you start the Jeep when dark. You will see a blueish (arching) light where you have a burnt or broken ignition wire, and the routing of your wires. Again....as Aggrex stated. Loll.
     
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  6. Sep 27, 2017 at 3:22 PM
    #6
    Jeeper79

    Jeeper79 [OP] Member

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    I really did not think so. I changed wires, plugs and coil be cause of this misfire. Maybe the injectors?
     
  7. Sep 27, 2017 at 3:23 PM
    #7
    Jeeper79

    Jeeper79 [OP] Member

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    2008 Rubicon 3.8L
     
  8. Sep 28, 2017 at 7:08 AM
    #8
    Prerunner1982

    Prerunner1982 Well-Known Member

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    Turn the engine off before checking the plug wires.... I don't know how many volts the ignition system on a 3.8 puts out, but a 350 Chevy with HEI (High Energy Ignition) will bite ya (20K+ volts). My arm was tingly for a couple days.

    May not hurt to check the chassis grounds.
     
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  9. Sep 28, 2017 at 12:19 PM
    #9
    OFFGRID

    OFFGRID Well-Known Member

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    Howell fuel injection, header, HEI distributor, TH350, NP208, SOA lift with YJ springs in the front & GW springs in the Rear. AMC20 with G2 1 piece chromos trussed, Dana 30 with G2 chromos and 760x ujoints and MM Stainless Hubs, Geared 4.56. Tom Woods shafts, Metal cloaks, Caged, 37" Toyo MTs.
    Missfires, could be a cam or crank sensor going out. It also could be the injectors going bad. I would double check all of your spark plug and wire connections. Do you have a check engine light?
     
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  10. Sep 28, 2017 at 1:37 PM
    #10
    Jeeper79

    Jeeper79 [OP] Member

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    Check engine light blinks but then goes solid if I don't out a load on it. Then goes away completely for a while and then comes back on
     
  11. Sep 28, 2017 at 2:03 PM
    #11
    aggrex

    aggrex Well-Known Member

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    Rent, borrow, buy a code reader to help diagnose your jeep problem(s)
     
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  12. Sep 28, 2017 at 2:23 PM
    #12
    Jeeper79

    Jeeper79 [OP] Member

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    I did and have tried 2 options already.
     
  13. Sep 28, 2017 at 2:23 PM
    #13
    Jeeper79

    Jeeper79 [OP] Member

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    Before I started asking questions
     
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  14. Sep 28, 2017 at 6:24 PM
    #14
    JKBob 25

    JKBob 25 Well-Known Member

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    I had an issue with my 2000 XJ. When it ran hot and over heated. The check engine light would for the same thing. Blink, go solid, then go out. Is your Rubi running hot or over heating? Or does the engine light come on as soon as you start it? I'm grasping at straws at this point based on previous posts.
     
  15. Sep 29, 2017 at 8:57 AM
    #15
    OFFGRID

    OFFGRID Well-Known Member

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    I'm not sure what you mean by this.

    Go to Oreillys, ask them to pull the codes, report back with the codes and any description they may give you. You might even take pictures of the screen and post on here for those like prerunner and aggrex who are very good with the ECM & electronic diagnostics.
     
  16. Sep 29, 2017 at 9:38 AM
    #16
    Prerunner1982

    Prerunner1982 Well-Known Member

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    Thanks but you are giving me too much credit.
     
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  17. Sep 29, 2017 at 11:06 AM
    #17
    aggrex

    aggrex Well-Known Member

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    Ahem, cough, burp;)
     
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  18. Oct 30, 2017 at 1:10 PM
    #18
    Jeeper79

    Jeeper79 [OP] Member

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    I think that the timing is off and it has to do with the ignition
     
  19. Oct 30, 2017 at 1:32 PM
    #19
    Prerunner1982

    Prerunner1982 Well-Known Member

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    Where you able to get the codes read? A bluetooth/wifi OBD2 reader from Amazon (or ebay if you choose) paired with the Torque app can be a great tool. I keep mine connected in my Jeep at all times and can connect to it anytime and get real time vehicle info, it can also read and clear codes.

    If it states a specific cylinder is misfiring I would suggest moving the injector (since you have already replaced the plug, wires, and coil) and see if the misfire follows the injector or remains on the same cylinder. You could also move the plug and wire just to see what happens, not impossible that you have a damaged plug or wire.
     
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  20. Oct 30, 2017 at 7:21 PM
    #20
    OFFGRID

    OFFGRID Well-Known Member

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    Prerunner. What OBD1/2 readers do you suggest? I am now in the need for these seeing as I have jumped into some computer controlled builds. Is the torque app free? Does it come with the reader?
     

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