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Discussion Starter #1
1990 deville 4.5: Just replaced my ISC motor and having issues with the adjustment. Set curb idle screw to the correct RPM and screwed the fully retracted plunger in all the way until it bottoms out, yet it's still in contact with the throttle causing a tiny gap preventing the throttle from resting on the curb idle screw. There's no room to set the .060 gap between ISC plunger and throttle. ISC is not increasing throttle for cold starts and ratchets after shutdown. Also I am unsure of the ISC learn procedure. Any help is appreciated.
 

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2004 Deville
2004 Deville, Silver, Gone, but not forgotten, 1972 Eldorado, 1974 eldorado, 1975 CDV
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596 Posts
I could be wrong, its been a while since i had my 89, but i think you need to unplug the electronic spark advance, unplug the iac motor, and ground the diagnostic connector to properly set the curb idle. Then adjust the idle screw until the tach reads 400, then put everything back the way it was.
 

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White Diamond '03 DHS (with DTS floor shift)
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If that ISC motor works the same as the later ones, press on the plunger first. It should retract. When it bottoms out, then unplug it and set the gap to .030. Gap is not critical, .030 is a good ball park.
 

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Discussion Starter #4
If that ISC motor works the same as the later ones, press on the plunger first. It should retract. When it bottoms out, then unplug it and set the gap to .030. Gap is not critical, .030 is a good ball park.
Screwed in and pushed in fully retracted the plunger is still flush up against the throttle. I'm wondering if I need to use washers on the ISC mounts at this point to create the gap.
 

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White Diamond '03 DHS (with DTS floor shift)
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86,242 Posts
Yeah, something doesn't sound right, but I don't remember enough about it to offer any more detailed advice.
 
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