Idle Set Screw
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Freshman User
Joined: Jan 2006
Posts: 36
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From: Dover AFB, DE
Idle Set Screw
I have an 85 302 EFI that i had to replace the throttlebody on. I picked up a "new" one for free and the problem is the PO messed with the screw. After i put it on the truck i have a whistle when holding the pedal at a steady speed. My first thought was either it didn't have a proper seal or i had a vacuum leak, which both checked out good. So i contacted him and asked him if the screw had been adjusted, and he informed me he had to try to compensate for an idle problem. I have searched the site, web, and shop manual and cannot find a procedure to reset it properly. Can anyone point me in the right direction to set it back?
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Joined: Jan 2001
Posts: 56,949
Likes: 2,718
From: Virginia
I disagree. Part of the idle air does go through the throttle plate. What seems to work ok is to disconnect the idle air control valve and set the idle at about 500-600rpm with the engine fully warmed up. Then plug it back in and it takes care of the other couple hundred rpm.
The screw being out of adjustment should not cause a whistling noise though. I would check the gaskets between the upper plenum and the intake manifold.
