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1989 Jeep Comanche 2.5l has a very high idle.

Discussion in 'Other Jeep Vehicles' started by 525JoeyYJ, Jan 10, 2017.

  1. Jan 10, 2017 at 1:59 PM
    #1
    525JoeyYJ

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    525JoeyYJ [OP] Well-Known Member

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    Hello, I've been fighting this issue for awhile now!!! It's getting on my nerves!!!!! My 1989 Jeep Comanche 2.5l has a very high idle, probably about 2000-2500 RPM... Not matter what I do, tap the gas or slam on the gas and let off, it comes back down to the place where it's currently idling and doesn't change even a hair... Tried replacing the TPS sensor, tried cleaning the TB, no change... But when I unplug the vacuum line on the MAP sensor, it idles where it should around 800 RPM or so...(I have dummy lights, no tach, so I'm guessing on the RPM's)... Then it runs a little rough, because it now has an open vacuum line sucking in extra air, but has a perfect idle speed 100% of the time... Tried replacing the MAP sensor... Same issue with absolutely no change... I'm stumped!!!!! Thanks in advance for any help! It would be very greatly appreciated!
     
    525JoeyYJ, Jan 10, 2017
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  2. Jan 10, 2017 at 10:38 PM
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    OFFGRID

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    OFFGRID Well-Known Member

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    Start with checking and replacing vacuum lines. Leaky vacuum is the #1 culprit for high idle. Also make sure your vacuum lines are routed correctly. Some vacuum ports only pull when the rpms are high, some pull only when the rpms are low, and some pull all the time.
     
    OFFGRID, Jan 10, 2017
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  3. Jan 11, 2017 at 2:53 AM
    #3
    525JoeyYJ

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    525JoeyYJ [OP] Well-Known Member

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    Okay, I'll check that again, though I already checked that pretty good.
     
    525JoeyYJ, Jan 11, 2017
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  4. Jan 11, 2017 at 6:16 PM
    #4
    525JoeyYJ

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    525JoeyYJ [OP] Well-Known Member

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    Checked all vacuum lines, all seem good. This all started when I removed my Gauge Cluster... When I removed it, I then put it back in, started it back up, and the idle jumped up really high, usually if I tapped on the gas... 15-20 taps would make the idle come down to normal, and would remain normal no matter what, until I shut it off and started it again... When it was cold it would idle good, then gradually work its way up to 2000-2500RPM, then I'd tap the gas 15-20 times and it would come down to normal, at this point, no matter what I do, the idle stays constant, unless I unplug the vacuum line to the MAP sonsor.
     
    525JoeyYJ, Jan 11, 2017
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  5. Jan 11, 2017 at 7:15 PM
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    C2T

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    C2T Well-Known Member

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    A way to check for vacuum leaks: Use a can of brake cleaner or carb cleaner and spray around the engine compartment and listen for an idle change.
     
    C2T, Jan 11, 2017
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  6. Jan 11, 2017 at 7:21 PM
    #6
    C2T

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    C2T Well-Known Member

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    Silly question but have you reset the computer? (Hint: disconnect the battery cables and touch them together for 30 seconds.)

    also, another idea...is the IAC functioning properly?
     
    C2T, Jan 11, 2017
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  7. Jan 12, 2017 at 6:07 AM
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    525JoeyYJ

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    525JoeyYJ [OP] Well-Known Member

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    I'm sure there are no vacuum leaks, sprayed every single one probably ten different times... I will check the IAC though. I have checked the TPS, but not the IAC. I will be taking off the throttle body today to clean that... I'll also be tapping new holes for the TPS while I'm at it because the damn screws broke off when I tried to unscrew them... Big surprise there...
     
    525JoeyYJ, Jan 12, 2017
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  8. Jan 13, 2017 at 4:01 PM
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    C2T

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    C2T Well-Known Member

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    Sorry, I am just tossing out ideas at this point. I am all out of "good" ideas so you are stuck with the bad ones from here. lol
     
    C2T, Jan 13, 2017
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  9. Jan 13, 2017 at 6:40 PM
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    525JoeyYJ

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    525JoeyYJ [OP] Well-Known Member

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    Lol, yeah, the IAC is a good idea though, I just haven't had time yet.
     
    525JoeyYJ, Jan 13, 2017
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  10. Jan 13, 2017 at 6:42 PM
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    C2T

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    C2T Well-Known Member

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    :fingerscrossed:
     
    C2T, Jan 13, 2017
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  11. Jan 15, 2017 at 5:28 AM
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    525JoeyYJ

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    525JoeyYJ [OP] Well-Known Member

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    Hello, I'm going to check my IAC today... I've been working long hours, haven't had much time.
     
    525JoeyYJ, Jan 15, 2017
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  12. Jan 23, 2017 at 8:20 AM
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    525JoeyYJ

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    525JoeyYJ [OP] Well-Known Member

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    Turned out to be the idle speed motor!!! My forever dreaded high idle is gone!!! Thank you all!
     
    525JoeyYJ, Jan 23, 2017
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  13. Jan 23, 2017 at 8:49 AM
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    OFFGRID

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    OFFGRID Well-Known Member

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    Yay!
     
    OFFGRID, Jan 23, 2017
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  14. Jan 23, 2017 at 6:00 PM
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    C2T

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    C2T Well-Known Member

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    Yippie!!! :yes:
     
    C2T, Jan 23, 2017
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  15. Jan 23, 2017 at 6:18 PM
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    chris4x4

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    chris4x4 With sufficient thrust, pigs fly just fine Moderator

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    :bananadance:
     
    chris4x4, Jan 23, 2017
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  16. Jan 23, 2017 at 6:32 PM
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    525JoeyYJ

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    525JoeyYJ [OP] Well-Known Member

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    Thanks again to all, I can't remember the last time I've been this happy!
     
    525JoeyYJ, Jan 23, 2017
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