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Discussion Starter · #1 ·
Hey everyone I have a question about setting the idle. I noticed there's a stud that the idle rest on with threads on both sides of it. I couldn't figure out what tool moves that stud to set the idle up. Is there an allen wrench on the inside of the stud? I don't want to use vise grips and mess up the threads. Thanks for your help.
 

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It is "Factory Preset", they adjust it at the factory and snap off the head. I have always replaced it with a new screw. Eventually a slight adjustment may be necessary because of wear,or in my case an adjustment was required due to mods. An allen head or long set-screw work fine.
 

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What's done to it? There really should be absolutely no reason to touch it. I've never heard of anyone tuning with the screw. If you're idling rough, you should be able to fix it by adjusting the IAC duty cycle with a tune.
 

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Discussion Starter · #6 ·
tocsboat24 said:
What's done to it? There really should be absolutely no reason to touch it. I've never heard of anyone tuning with the screw. If you're idling rough, you should be able to fix it by adjusting the IAC duty cycle with a tune.
It's actually not idling rough, just low. I just took it to the shop and they did this test with a smoke machine (I don't actually know the name of the machine) where they pump smoke into your engine and if you have a vacuum leak it comes out. Plus they cleaned the maf, everything came out fine. It just idles slow but it stays right at the same rpm, it actually idles VERY smooth!

Anyway, I just set it up a tad (y'know, a smidgen) and it runs fine now....it better, it's going on a 5,000 mile trip in a month!!
 

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I did the same last week i cleaned the IAC valve thinking that it would run better NOT!! so had to buy a new one for $80 it runs sweet know.mine was staling coming to a stop and bad iding.
 

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Idle screw

tocsboat24 said:
There should be no need to touch that screw. It's factory preset, and if you think you need to adjust it, you have another problem.
Mine required a tweak due to going from 4.6 to 5.4L SC. The idle speed would drop down too low before the IAC could settle. The IAC will adjust to compensate, however it may be at too high of duty cycle because of mods making it unstable. I have used the Idle screw adjustment to help minimize surge from bigger cams.
 

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gboger said:
Mine required a tweak due to going from 4.6 to 5.4L SC. The idle speed would drop down too low before the IAC could settle. The IAC will adjust to compensate, however it may be at too high of duty cycle because of mods making it unstable. I have used the Idle screw adjustment to help minimize surge from bigger cams.
That's using the same TB for a different motor, so nothing's to say it wasn't adjusted differently on the 5.4Ls, so I could understand that. But with a stock, or nearly stock motor, there should be no reason to adjust that. It's not like an old carbureted car, there's quite a bit more going on.
 
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