Proper adjustment of Throttle body idle stop

[gto78]

I've looked through all the maint manuals I can get my hands on and had no luck on how to properly set the idle stop screw on the throttle body. It's there for some reason, but all the manuals say it's not adjustable and "preset". I'm thinking the best position is determined by opening the butterfly just enough to see a rise the the TPS sensor, and then backing it off about a turn?

This leads to my next concern- the "Scan gauge" tester I use to monitor the sensors is telling me that the TPS doesn't go any lower than 19% at idle, and no higher than 81% at full WFO throttle. Is this typical? I tried another sensor with the same results except it had a low stop setting of 16% idle.

 

[ExplorerDMB]

Did you see a voltage instead of percentage - I'm use to voltage readings. But that probably sounds about right (those precentages in retrospect to voltage)

-Drew

 

[EMG7895]

The valve is supposed to rest at 10 degrees open( if I remember correctly). This is what the computer expects, and what the tps mod does to "recalibrate" an old tps.

 

[gto78]

The valve is supposed to rest at 10 degrees open....

Wow, ten degrees. Mine is shut completely as far as it will go, and the opened just a slight hair. My idle runs at 620 to 650 no matter what position the throttle body is in. I guess it isn't critical as long as it's not at the extreme limit of the IAC unit's capability of maintaining a normal idle.

 

[EMG7895]

This should help clear things up: