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4.0 misfiring

Discussion in 'General Jeep Discussion' started by fishtale77, Sep 21, 2016.

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  1. Sep 21, 2016 at 10:05 AM
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    fishtale77

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    fishtale77 [OP] Member

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    I have a Grand Cherokee 2001 4.0 with 165000 miles. While it is idling the gauge is jumping and there is a thumping noise. The code says the timing chain is stretched or not working. what kind of price am I looking at to have it repaired. Thanks for any info
     
    fishtale77, Sep 21, 2016
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  2. Sep 21, 2016 at 12:13 PM
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    C2T

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    C2T Well-Known Member

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    I would anticipate a bill for about 4 to 5 hours from your local mechanic, though it can and will vary. Parts are cheap enough @ <$100.00.

    My local Jeep dealer's wrench turners bill out at about $100/hr. and non-dealer mechanics are often about $65/hr to 75/hr. So I would estimate between $400 and $600 if that is all that is wrong with it.

    It is not a hard job if you have a garage and the correct tools...but it does take some time.

    I hope this information helps. Good Luck!!
     
    C2T, Sep 21, 2016
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  3. Sep 21, 2016 at 12:13 PM
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    C2T

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    C2T Well-Known Member

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    oh...and welcome to the forum. :)
     
    C2T, Sep 21, 2016
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  4. Sep 21, 2016 at 1:03 PM
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    fishtale77

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    fishtale77 [OP] Member

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    Hey thanks. That gives me an idea of the cost.
     
    fishtale77, Sep 21, 2016
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  5. Sep 21, 2016 at 1:11 PM
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    C2T

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    C2T Well-Known Member

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    No problem. Take it all with a grain of salt though....I don't claim to be an expert and it can change a good deal from place to place.

    :)
     
    C2T, Sep 21, 2016
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  6. Sep 21, 2016 at 1:40 PM
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    fishtale77

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    fishtale77 [OP] Member

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    Does anyone have any suggestions on what else i should have done while the mechanic has the motor open? Thanks
     
    fishtale77, Sep 21, 2016
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  7. Sep 21, 2016 at 2:10 PM
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    C2T

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    C2T Well-Known Member

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    Well, it is a great time to replace your fan belt and if your water pump is having issues, he has to remove that to get to the timing chain anyway so it won't cost much more than the pump itself. Other than that, the mechanic will likely give it the once over when he starts working on it.

    :)
     
    C2T, Sep 21, 2016
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    VOZ likes this.
  8. Oct 6, 2016 at 4:52 AM
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    fishtale77

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    fishtale77 [OP] Member

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    Well the shop says its not the timing chain. I changed the plugs and it fixed the missfire for about a week. Then it came back. Then they changed the crank shaft position sensor. That fixed the problem for about a week also. Then yesterday it started worse than before. Now i cant even drive it cause its missfiring so bad. I checked the plugs and one was real black with soot.someone suggested to change the 2 o2 sensors on the exhaust. Any suggestions on what else to try. Thanks
     
    fishtale77, Oct 6, 2016
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  9. Oct 6, 2016 at 8:44 AM
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    C2T

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    C2T Well-Known Member

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    On the cylinder that was all black...you might try checking/changing the injector. Just did that on a TJ last weekend over misfiring and power problems. A new injector fixed that one. A compression test might be called for too.
     
    C2T, Oct 6, 2016
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  10. Oct 6, 2016 at 8:29 PM
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    OFFGRID

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    OFFGRID Well-Known Member

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    do you have coil packs or distributor in your jeep. Sounds electrical to me. Could be a spark plug wire or wires grounding out. Coil packs may be going bad. The one plug that is all black, is it getting spark. Here is a link to test for spark.

    https://www.youtube.com/watch?v=VnfcMSKskjY
     
    OFFGRID, Oct 6, 2016
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  11. Oct 13, 2016 at 3:28 PM
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    fishtale77

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    fishtale77 [OP] Member

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    The coil packs are new. Plugs new. Camshaft sensor new. Pigtail Plug to that sensor is new. I might change the o2 sensor for that cylinder.im guessing the upstreem one. There are 4. And about 50 bucks each
     
    fishtale77, Oct 13, 2016
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  12. Oct 13, 2016 at 3:29 PM
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    fishtale77

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    And i think it only missfires when the temp gauge gets to just under halfway.
     
    fishtale77, Oct 13, 2016
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  13. Oct 13, 2016 at 4:06 PM
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    C2T

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    C2T Well-Known Member

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    Possibly silly questions...did you check your coolant temp sensor? When those go bad they cause the system to run really poorly...including misfiring. A thought....
     
    C2T, Oct 13, 2016
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  14. Oct 15, 2016 at 10:42 AM
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    fishtale77

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    fishtale77 [OP] Member

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    Thats a good idea. The other day it was running too hot. So i changed the thermostat. Seems to have fixed that. Ill try the temp sensor
     
    fishtale77, Oct 15, 2016
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    C2T likes this.
  15. Oct 15, 2016 at 3:40 PM
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    fishtale77

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    fishtale77 [OP] Member

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    Nope. Wasnt the temp sensor. Put a new one in
     
    fishtale77, Oct 15, 2016
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  16. Oct 15, 2016 at 4:02 PM
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    C2T

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    C2T Well-Known Member

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    Damn! and that was my best last WAG too.
     
    C2T, Oct 15, 2016
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  17. Oct 15, 2016 at 9:18 PM
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    OFFGRID

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    OFFGRID Well-Known Member

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    You haven't said if you changed your plug wires, Bad wires will cause symptoms like that. If 1 or more wires are grounding out or not making a good connection the engine will not run well. In case it is not the wires, You said that you have a plug that is black, and you changed the plugs. You found one was black again. Is it black with engine oil and gummy oil residue, or is it dry black soot. What I'm getting at is that if it's been running hot like you said (did it overheat). If it overheated you're opening a whole other can of worms.
     
    OFFGRID, Oct 15, 2016
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  18. Oct 16, 2016 at 3:06 AM
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    fishtale77

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    fishtale77 [OP] Member

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    Dont have wires. The coil packs r new though. And it didnt over heat. The plug was black with dry soot
     
    fishtale77, Oct 16, 2016
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  19. Oct 16, 2016 at 7:22 AM
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    OFFGRID

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    OFFGRID Well-Known Member

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    Check each wire for a good "TIGHT" connection on each plug, especailly the black plug. You said that it ran fine after installing new plugs then started acting up again. Maybe one of the wires is not getting a good connection. Something electrical sounds like it is wiggling around. I'm just guessing.

    Do you know what the actual code is?
     
    OFFGRID, Oct 16, 2016
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  20. Oct 16, 2016 at 7:32 AM
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    OFFGRID

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    OFFGRID Well-Known Member

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    Did a quick little search. This is what I found. "Normally misfires are plugs/boot, carbon build up, or injector/fuel pump problem.", and "I'd start with testing fuel pressure with a fuel pressure gauge at the schrader valve on the fuel rail.

    Troubleshooting is a process of elimination. Have to start with the basics and solid fuel delivery is one of them.

    With a 2001, you're looking for around 49 psi plus or minus 5."
     
    OFFGRID, Oct 16, 2016
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