Why can't I get my IAC counts lower?

[forrer13]

Guys, help me figure out why I can?t get my IAC counts below 134.

I have a 5.3LS throttle body on a LS6 intake on my 5.3LS engine. The engine has a mild cam, about the same as an LS6 cam and some mild porting and polishing done to the factory 862 heads.

Fully warmed up (190F +) I can not get my IAC counts below 134. I have opened the TB, and reset the TPS to zero multiple times but the IAC counts will not go any lower. If I adjust the TB any further I will be out of the idle circuit due to TPS voltage currently at about 0.64v (% open is zero)

I have been advised against drilling the TB blade and I am wondering if it would do anything anyways, as opening the TB further is having no effect in IAC counts, it just raises the idle speed.

Check out the log attached. Between that start of the log and the end I opened the TB blade 1/2 a turn of the set screw. Compare the IAC counts from the first part of the log to the last and you will not see much difference. This is why I don't believe further adjustments or drilling the TB blade would do anything more than just raise the idle RPM.

[kingtal0n]

make sure you have a full OEM Pcv system

some of the airflow through PCV will help raise the idle, close IACV

Do not recommend drilling any holes just to create a vacuum leak,

if you just want to let air in as if to bypass the throttle body, instead of drilling a hole somewhere just create a vacuum leak,

same thing hole = vacuum leak the only difference is the hole cannot be undrilled whereas a vacuum leak can be plugged easily.

[Ben Charles]

TPS volts usually don’t get out of whack till roughly .82 volts (are you doing a TPS/iac reset?)