Throttle Body Blades wont close completley

[BIGCHEVY4X]

I have been fighting a high idle with a tbi blazer i just put back together. ive replaced some sensors and got the thing running right but the high idle is still there. Did the iac reset several times and it seems to work until i drive it and turn it off and then start it again and its back. I was messing with it today and turns out the tbi blades arent closing all the way. Its a bored throttle body from XtremeFI. I disconected the throttle cable and TV cable and it still does it. Didnt have a chance to look at the TPS sensor to see if it could be hanging it up. Is there anything else that could be doing it? I want to be sure before I email XtremeFI and complain. Thanks

 

[Blue85]

Sometimes the holes the throttle shaft ride in wear and it causes problems like this. The rebuilder should check and drill for bushings if required.

 

[454Sub]

If the throttle body has been bored, the blades had to be removed. When they reinstalled them, they may not have centered the blades on the shafts correctly. I did that to mine when I bored mine out, and it idled high. I just loosened the blades, snapped it open and shut a few times, and it finally centered in the bores and closed all the way. Or your idle screw has been messed with. If you can see the screw (small Torx head), it 99% likely has been tampered with. If you just see a basically small freeze plug, its good.

 

[BIGCHEVY4X]

The idle screw cover is gone. I backed the screw all the way out to verify it wasnt that. I will try to adjust the blades on the shaft tonight.

 

[454Sub]

Alright, now that the idle screw has been tampered with, you have to reset the idle to make the puter happy. There is a procedure to doing this. Google it, I cant remember it off hand, but if you dont do it, you will never get it running right.

First, make sure the blades are adjusted and centered. After that, assuming everything is in order, you will have to do the thing I mentioned above.

 

[blaznjon]

could be the iac is worn out.or dirty.the throttle blades don`t close all the way with out backing the screw off any way.I had the opposite problem before where i could reset iac after i had cleaned it and manually back seated it.get a good normal idle the first time.shut it off and not get the high idle at start up the little rack threads or what ever you call them were worn in one spot.i switched the iac with a spare and it worked like it should have.