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  1. #41
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    Re: Jeep TJ cylinder 3 misfire, please help me diagnose

    Quote Originally Posted by JPNinPA View Post
    PS its a CCV not a PCV
    Unlike a PCV valve there is no one way valve in the CCV.


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    Sweeet thanks. While I am getting the head done, anything else I should change while I have it open? Lifters? Push rods? The engine was running perfectly prior to the burnt valve.

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    Re: Jeep TJ cylinder 3 misfire, please help me diagnose

    Was there any knocking noise or noisy lifter? Inspect them if high milage change for piece of mind.
    Also look at cam for worn lobes.

    But not really necessary to change more.


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    "Never look down on anybody unless you're helping him up" - Jesse Jackson

  3. #43
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    Re: Jeep TJ cylinder 3 misfire, please help me diagnose

    Quote Originally Posted by JPNinPA View Post
    Was there any knocking noise or noisy lifter? Inspect them if high milage change for piece of mind.
    Also look at cam for worn lobes.

    But not really necessary to change more.


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    So I did a leak down test, and there was no significant leakdown in any of the cylinders. I repeated the test and got the same results. Also did a wet compression test and got normal results. I don't think I will be tearing it apart just yet. There has to be something I haven't considered...

  4. #44
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    Jeep TJ cylinder 3 misfire, please help me diagnose

    Just to restate your issue. The rough running and misfire happens below 2000 rpm. It does not matter if started cold or warm or at idle or running while driving. It only happens below 2k rpm.

    I still say that fuel pressure oscillating is not normal. It should be steady like it is at 2k rpm.

    Do you mind posting the values by cylinder that you measured on both the compression and leak down test?
    While you had the plugs out to do the compression test and leak down did you look at them? Mind posting pics? Tip, threads and ceramic.
    And of the boot that goes over the plug?

    Have you ever taken the intake or exhaust off? Or let me ask it differently. Was the intake or exhaust manifold ever off of the engine?

    Also the paper or rag you hold near the exhaust does not show any sucking in. You need a flat sheet closer to the exhaust. It should always be being pushed away. A bad valve would suck the paper in the pipe. It should almost pull it out of your hand. Actually I don't hear any miss firing more like no firing. No backfiring.

    Have you ever pulled the ODPA oil drive pump assembly? The thing that sits where the distributor would be. On 04-06 there was a huge issue but timing can be off on any vehicle if either the ODPA is set wrong or it's gears are worn. BE WARNED you can't just pull it out and stick it back in. There are directions to follow, so you don't miss a tooth and throw the timing way off.

    How good is the ground from the battery to the engine? If measuring res it should be less than 1ohm.

    What is your battery voltage off, at idle, at 2000rpm or higher?

    Lastly do you have a field service manual? Find one and buy it. It has every test and measurement. Described correctly.

    Regards,
    JPNinPA

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    Last edited by JPNinPA; 08-29-2019 at 08:29 PM.
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  5. #45
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    Jeep TJ cylinder 3 misfire, please help me diagnose

    Still think the jumpy fuel pressure is a cause or symptom.

    So you didn't give all the info.

    And there is no such a thing as analysis paralysis. Unless you make no changes. It just sounds cool and a pressuring statement.


    From another forum:
    "Replaced the coil and absolutely no difference. Also put on the injector 3 shield and no difference. I notice it begins right after the vehicle warms up and goes into open loop. Also, I notice that the injector 3 doesn't click as strong as the rest (by placing my finger over each injector). "

    "Thank you for the reply! It's exactly as you say, when I clear the code, the jeep behaves better for a while until it throws the code again. Although I put the heat shield on and it is not making any difference. Was wondering what else I can try to make this misfire gremlin go away."

    So when you clear the codes it runs fine for a while? Then it is a sensor.
    And it only happens after warmup.

    Try measuring the temp sending unit resistance from cold as the engine heats. It should be steady resistance change.

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    Regards,
    JPNinPA

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    Last edited by JPNinPA; 09-07-2019 at 07:52 PM.
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  6. #46
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    Re: Jeep TJ cylinder 3 misfire, please help me diagnose

    Quote Originally Posted by JPNinPA View Post
    Still think the jumpy fuel pressure is a cause or symptom.

    So you didn't give all the info.

    And there is no such a thing as analysis paralysis. Unless you make no changes. It just sounds cool and a pressuring statement.


    From another forum:
    "Replaced the coil and absolutely no difference. Also put on the injector 3 shield and no difference. I notice it begins right after the vehicle warms up and goes into open loop. Also, I notice that the injector 3 doesn't click as strong as the rest (by placing my finger over each injector). "

    "Thank you for the reply! It's exactly as you say, when I clear the code, the jeep behaves better for a while until it throws the code again. Although I put the heat shield on and it is not making any difference. Was wondering what else I can try to make this misfire gremlin go away."

    So when you clear the codes it runs fine for a while? Then it is a sensor.
    And it only happens after warmup.

    Try measuring the temp sending unit resistance from cold as the engine heats. It should be steady resistance change.

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Size:  55.8 KB







    Regards,
    JPNinPA

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    Thank you for the reply. Haven't gotten around to working on it due to work. Hopefully will have a chance in a few days.

    Where it currently sits, its throwing a cylinder 1 code now. I was ale to start and drive it for about 10 minutes without a single hiccup or hesitation. I turned it off and restarted and it began doing it again. I have the following parts waiting for me

    iridium spark plugs
    Fuel pump relay
    Map sensor
    All 4 NTK oxygen sensors.

    Have never taken the intake or exhaust off. The compression values were all about 160+/- 10psi. Leak down test I used the compression testor and hooked it up to an air tank, brought the piston to top dead center and tested each cylinder. Did not leak any air over the 15 minutes I allowed for each cylinder.

    If I replace the above parts and it still does the issue, next thing I will replace is the fuel pump, followed by the coolant temperature sensor.

    At that point, there is nothing left for me to change and I will have to take it into a local shop to help me out. Ideally, they could identify the issue and I can swap it out at home. Found a local head shop which has entire heads ready for a fair price, but the negative dry and wet compression tests as well as the leak down test makes me not suspect the problem being internal (and also, it has bouts of running just fine, so if it was mechanical, this would not be possible)

  7. #47
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    Jeep TJ cylinder 3 misfire, please help me diagnose

    Send a pic of the old plugs by cylinder showing tip thread and ceramic.

    Check the wiring to all sensors as you change them.

    To clarify and please correct. Details are great value.


    If you reset the codes by disconnecting the battery and shorting the pos cable to negative for 30 sec. Then reconnecting the battery.
    The issue does not happen until up to temperature and some driving?
    How far or how many starts until it repeats. Or as soon as it heats it's back?

    And once the code is thrown it happens each start as soon as it reaches temp.

    Regards,
    JPNinPA

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    Last edited by JPNinPA; 09-09-2019 at 07:38 PM.
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  8. #48
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    Re: Jeep TJ cylinder 3 misfire, please help me diagnose

    Quote Originally Posted by JPNinPA View Post
    Send a pic of the old plugs by cylinder showing tip thread and ceramic.

    Check the wiring to all sensors as you change them.

    To clarify and please correct. Details are great value.


    If you reset the codes by disconnecting the battery and shorting the pos cable to negative for 30 sec. Then reconnecting the battery.
    The issue does not happen until up to temperature and some driving?
    How far or how many starts until it repeats. Or as soon as it heats it's back?

    And once the code is thrown it happens each start as soon as it reaches temp.

    Regards,
    JPNinPA

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    I will do as you mentioned and get back to you. Made another video update of where I am:

    I fix a vacuum leak from the CCV as well as show my leak down test apparatus. Repeated in all 6 cylinders x2 over (took forever).

  9. #49
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    Jeep TJ cylinder 3 misfire, please help me diagnose

    Brake cleaner is fairly harsh.
    Water, WD 40, TB cleaner, carb cleaner all work as well and less harsh.

    CRC brakekleen has toluene in it and that reacts with many materials. It is used as paint thinner and can melt/degrade rubber.


    “Toluene is a common solvent, e.g. for paints, paint thinners, silicone sealants,[20] many chemical reactants, rubber, printing ink, adhesives (glues), lacquers, leather tanners, and disinfectants.[19]”

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    Last edited by JPNinPA; 09-09-2019 at 10:26 PM.
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  10. #50
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    Re: Jeep TJ cylinder 3 misfire, please help me diagnose

    I just kicked my dogs out of the cave, n I'm taking a nap.
    Needs to go yonder.

  11. #51
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    Re: Jeep TJ cylinder 3 misfire, please help me diagnose

    Wish I could help, but I'm constant learning here when it gets deep. The nap was wonderfull, and one of the dogs killed a possom.
    LIFE IS GOOD !
    Needs to go yonder.

  12. #52
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    Re: Jeep TJ cylinder 3 misfire, please help me diagnose

    Quote Originally Posted by JPNinPA View Post
    Brake cleaner is fairly harsh.
    Water, WD 40, TB cleaner, carb cleaner all work as well and less harsh.

    CRC brakekleen has toluene in it and that reacts with many materials. It is used as paint thinner and can melt/degrade rubber.


    “Toluene is a common solvent, e.g. for paints, paint thinners, silicone sealants,[20] many chemical reactants, rubber, printing ink, adhesives (glues), lacquers, leather tanners, and disinfectants.[19]”

    Sent from my iPhone using Jeepz.com mobile app
    I used WD 40 on a new sterret dial caliper thinking I was taking well taken care of it. It desolved the glue that holds the measureing plate on to the caliper. So be careful, in my opinion. Anything that acts as a penetrite , you have to think about it.
    Needs to go yonder.

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