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93 XJ 4.0 Check engine light, running rough, loss of power

Discussion in 'Cherokee' started by Chipmunk_Stampede, Mar 31, 2018.

  1. Mar 31, 2018 at 2:54 PM
    #1
    Chipmunk_Stampede

    Chipmunk_Stampede [OP] Member

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    Vash
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    Heya, so I have a '93 Laredo with the 4.0L and I need some help troubleshooting it. I replaced the CCV elbow up front, and immediately after I got a check engine light and she's not running right. The code says injector fault, but all my injectors are good, I replaced the distributor cap, rotor, plugs, and wires to no avail. The truck shakes while accelerating, and sounds like a lawn mower engine for lack of a better description.
    Anyone know what's going on?
    Thanks in advance!
    -Vash
     
  2. Mar 31, 2018 at 3:52 PM
    #2
    chris4x4

    chris4x4 With sufficient thrust, pigs fly just fine Moderator

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    Welcome aboard! Start with the basics, Vacuum lines, intake leaks, etc. Those can cause similar symptoms
     
  3. Mar 31, 2018 at 4:15 PM
    #3
    Chipmunk_Stampede

    Chipmunk_Stampede [OP] Member

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    I checked all the vacuum lines, air filter is good. I'll double check the intake. It was running fine before I replaced that elbow, and it shattered in my hand when I went to pull it out. I put the new one in, and the light immediately popped on. I'm wondering if it's the crank positioning sensor, I don't think it's ever been replaced, but I'm not seeing a correlation.
     
  4. Mar 31, 2018 at 4:28 PM
    #4
    chris4x4

    chris4x4 With sufficient thrust, pigs fly just fine Moderator

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    Good point. Any chance its not sealed or installed correctly?
     
  5. Mar 31, 2018 at 5:19 PM
    #5
    Chipmunk_Stampede

    Chipmunk_Stampede [OP] Member

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    There is a chance, and I didn't even think of that. I may have roughed up the seat for the rubber gasket piece getting the old one out. I'll slap some RTV on it and see if that doesn't do the trick. :)
     
    chris4x4 likes this.
  6. Mar 31, 2018 at 5:23 PM
    #6
    chris4x4

    chris4x4 With sufficient thrust, pigs fly just fine Moderator

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    Let us know if it does.
     
  7. Mar 31, 2018 at 5:35 PM
    #7
    Chipmunk_Stampede

    Chipmunk_Stampede [OP] Member

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    Will do. It ain't pretty, but I ran a good bead on the rubber seal against the valve cover, and again between it and the elbow. I'll give it some time time to set up and see how it's doing.
     
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  8. Mar 31, 2018 at 6:20 PM
    #8
    aggrex

    aggrex Well-Known Member

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    Welcome! Since the problem(s) started after replacing the CCV then just focus there before venturing elsewhere. Make sure everything you replaced is installed correctly as RTV is usually not required.
     
  9. Mar 31, 2018 at 7:41 PM
    #9
    Chipmunk_Stampede

    Chipmunk_Stampede [OP] Member

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    My thought exactly, and the RTV only made my valve cover more colorful.
    I'm starting to wonder if when the original elbow shattered if I lost a couple pieces in the valve cover, so tomorrow I'm gonna pop it off and look. I also have a buddy bringing his OBD scanner over so I can check the code again.
    I've had this truck for 12 years, it has over 500k miles on it, and this is the first time I've been scratching my head over an issue.

    Also, anyone know what the ohm value should be for the crankshaft positioning sensor? I figure it won't hurt to check.
     
  10. Mar 31, 2018 at 8:34 PM
    #10
    chris4x4

    chris4x4 With sufficient thrust, pigs fly just fine Moderator

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    I found this:

    http://atlib.info/blog/133-how-do-i-check-a-crankshaft-position-sensor
     
    Bob likes this.
  11. Apr 1, 2018 at 9:50 AM
    #11
    2oldjeeps

    2oldjeeps Well-Known Member

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  12. Apr 1, 2018 at 9:51 AM
    #12
    2oldjeeps

    2oldjeeps Well-Known Member

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    oops, better pix

    a cps 1.jpg

    2.5v peak pulse, spacing changes with rpm...
     
    aggrex likes this.
  13. Apr 1, 2018 at 1:57 PM
    #13
    Chipmunk_Stampede

    Chipmunk_Stampede [OP] Member

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    I'm working backwards from the issue at this point. About all that makes sense is that a piece of the old elbow fell into the valve cover, so I'm about to pop it off and take a look. Otherwise it's just the Jeep gods messing with me and it's completely unrelated. Let's have a look in the valve cover!
     
  14. Apr 6, 2018 at 1:01 AM
    #14
    Chipmunk_Stampede

    Chipmunk_Stampede [OP] Member

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    Just wanted to let y'all know I haven't forgotten about ya. I apparently passed a kidney stone and have been laid up for a few days, but I got a new valve cover gasket today and I'm opening her up in the morning. I'll let y'all know what I find.

    On another note, can anyone advise a good place to get a new yoke for my driveshaft? The one in the back of the transmission is worn and I'm getting that "clunk" when I shift into gear. Thanks in advance!
     
  15. Apr 6, 2018 at 7:09 AM
    #15
    chris4x4

    chris4x4 With sufficient thrust, pigs fly just fine Moderator

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    Oh man! My Wife had a kidney stone, and she was a mess! Hope youre better
     
  16. Apr 6, 2018 at 8:28 AM
    #16
    aggrex

    aggrex Well-Known Member

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    Hope your feeling better! Local parts stores should stock replacement drive shaft pinion yoke, CV H yoke, axle yoke etc.
     
  17. Apr 6, 2018 at 4:36 PM
    #17
    Chipmunk_Stampede

    Chipmunk_Stampede [OP] Member

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    I FIXED IT!

    Okay, so just under the elbow in the valve cover there is a metal plate that I'm assuming regulates the airflow into the elbow. When I was prying the old elbow off it looks like I bent it upwards on one side. I bent it back down, problem solved.
     
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  18. Apr 6, 2018 at 4:36 PM
    #18
    Chipmunk_Stampede

    Chipmunk_Stampede [OP] Member

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    But, on our test drive the check engine light popped back on.....
     
  19. Apr 6, 2018 at 4:48 PM
    #19
    aggrex

    aggrex Well-Known Member

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    Disconnect the battery to see if it clears the CEL. If the CEL returns identify the code and start from there.
     
    OFFGRID and chris4x4 like this.
  20. Apr 16, 2018 at 6:22 AM
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    Singlemann

    Singlemann New Member

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    I'm having the same problem. Is this what actually fixed it? Cause mine started after I replaced the transmission.
     

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