Help my 91 cadilliac deville 4.9
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HT4100 4.1, 4.5, 4.9 Discussion, Help my 91 cadilliac deville 4.9 in Cadillac Engine Technical Discussion; Help my 91 deville is idle out of control i replaced the idle control sensor and the pigtail and i ...
  1. #1
    rocken is offline Cadillac Owners Member
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    Unhappy Help my 91 cadilliac deville 4.9

    Help my 91 deville is idle out of control i replaced the idle control sensor and the pigtail and i fired it up and its rpms are about 7ooo and i dont know what or where to go next please help me

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  3. #2
    Ranger's Avatar
    Ranger is offline Cadillac Owners Member
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    Re: Help my 91 cadilliac deville 4.9

    Press on the plunger till it retracts. When it bottoms out, pull the plug. Set the gap between the plunger and the throttle linkage to .060. Plug it back in and you are done.

  4. #3
    carnut is offline Cadillac Owners Master
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    Re: Help my 91 cadilliac deville 4.9

    With the key on, engine off, open the the throttle and as Ranger says, depress the idle solenoid shaft till it fully retracts, then release the throttle arm. Then quickly disconnect the ISC electrical connector. You should see a small air gap between the throttle and the shaft. If not, screw in the shaft gently till you get .060 gap. Then turn key off, wait 10 seconds and restart the car. It should race for a few seconds then calm down to approx 600 RPM. Do this with the climate control system off. Once idling normally, turn the climate system back on to AUTO mode. You should see the ISC shaft extend just before the A/C compressor engages. I'm sure you meant 700 RPM not 7000!!!

  5. #4
    rocken is offline Cadillac Owners Member
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    Re: Help my 91 cadilliac deville 4.9

    no i meant 7000 rpm shes going crazy but ill try that guys thanks

  6. #5
    rocken is offline Cadillac Owners Member
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    Re: Help my 91 cadilliac deville 4.9

    hey guys i tried pushing on the screw on the idle speed control it didn't go in am i doing it right or not i turn the key to the on position and push nothing happen

  7. #6
    HUF's Avatar
    HUF
    HUF is offline Cadillac Owners Connoisseur
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    Re: Help my 91 cadilliac deville 4.9

    It moves very slowly when you press it. You should keep the throttle lever up with one hand and push the ISC motor plunger with other. If it does not move at all, the switch inside the ISC motor is bad.

  8. #7
    HUF's Avatar
    HUF
    HUF is offline Cadillac Owners Connoisseur
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    Re: Help my 91 cadilliac deville 4.9

    Quote Originally Posted by rocken View Post
    no i meant 7000 rpm shes going crazy but ill try that guys thanks
    4.9 cannot make 7000 RPM...

  9. #8
    carnut is offline Cadillac Owners Master
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    Re: Help my 91 cadilliac deville 4.9

    No way!! 7000 RPM at idle? The fuel will shut of way before that. We can only assist or try to help with proper clues.

  10. #9
    carnut is offline Cadillac Owners Master
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    Re: Help my 91 cadilliac deville 4.9

    You might try taking the idle motor back off, reconnect the pigtail to it then with key on, car off, retract it in the palm of your hand with your thumb. Thats assuming you repaired the pigtail correctly and have power to the idle motor.

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