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Author Topic: Idle screw adjustment  (Read 2686 times)

greywolf27030

  • Old-Timer
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  • Posts: 1658
    • 1991 XR2, 1992 XR2, 1993 XR2
Idle screw adjustment
« on: December 23, 2015, 09:53:15 AM »

Okay, I've got coolant flowing though the IAC and I'm going from a proper fast idle to warm idle.  Warm idle is about 850RPM or so by the factory tach.  My engine doesn't seem to like it that low.  The power steering doesn't function and any electric load causes idle to dip when turned on.  I'm wondering if the idle is adjusted properly.  Considering some of the repairs done by the PO, I'm sure the don't touch screw has been messed with.  How do you determine if the throttle is in it's correct position?

Merry Christmas,  Jack Byrd
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Jack Byrd

mitch1204

  • Sr. Member
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  • Posts: 401
    • 1991 Mercury Capri NA Auto/ 1994 Mercury Capri NA
Re: Idle screw adjustment
« Reply #1 on: December 23, 2015, 02:03:33 PM »

Do you have the auto Jack. Seems to me you were looking for one awhile back or I'm losing my mind, lol.

My auto idles fine at 850 and drops to about 750 in gear. It sounds like you have another issue like a small vacuum leak or perhaps weak fire, maybe a ground corrosion issue. Does your rpms take a drop when you brake?

You can compensate with the idle screw but it would effect your fuel mileage. It would be better to find the culprit. You should never have to touch that screw unless someone has messed with it before.
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greywolf27030

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  • Posts: 1658
    • 1991 XR2, 1992 XR2, 1993 XR2
Re: Idle screw adjustment
« Reply #2 on: December 24, 2015, 09:59:30 AM »

Thanks Mitch.  I've got a manual, so I really shouldn't have a problem.  Vacuum leak sounds interesting.  Prior to re-establishing coolant flow to the IAC, I had a cold idle that fluctuated between 2200 and 2500 like you were pressing and releasing the pedal constantly, warm idle was about 1500.  Because of the other messes I've encountered, I can't imagine the PO didn't fool with that throttle position screw.

Jack
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Jack Byrd

greywolf27030

  • Old-Timer
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  • Posts: 1658
    • 1991 XR2, 1992 XR2, 1993 XR2
Re: Idle screw adjustment
« Reply #3 on: December 27, 2015, 06:15:28 PM »

Well, hosed down the running engine with brake cleaner and  there doesn't seem to be any vacuum leaks.  Gotta find time to check out the manual and see what it says about adjusting idle.

Jack
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Jack Byrd