Problem with pushing in clutch/ idle with AC on...

[slammin86]

A little back story here. I recently swapped heads on my 04 gto and have been in the process of redoing the idle. Mods are as follows.

229/234 .612/.600 111+4 cam
Trick flow 220's hand ported
Fast 92/92 combo runners ported to match heads
Kooks 1 3/4" headers with catless mids
OTRCAI
SD tune

I have been slowly dialing in my RAF and everything else. The car idles at 800 rpm with an IAC of 60 ish. I do reset the IAC and TPS whenever I mess with the idle screw. I had an issue with the bottom of the idle screw having a burr and hanging up on the stop on the tb itself. I recently took the tb off and smoothed this out.

Here is my problem. With the car running at any given speed I can push the clutch in without the AC on and everything is fine. I can free rev with the car at a stop without the AC on and it is fine. But if I turn the AC on the car always wants to stall out or die. Also when parked without the ac on the STIT stays close to zero. With the AC on it always wants to add here.

I am logging an Idle AC Airflow parameter and it always adds 1.5 ish at idle. I think if I could find out where to adjust this at I could solve the problems but so far I have not found it.

At this point I am tired of blindly changing things to see if they help or hurt so I am asking for help.

Attached is my config file, my tune, and a log. The log shows me driving with the AC on and pressing the clutch in. You can see the rpm's drop way down. I then turn the AC off and repeat the same thing and the car just drops to idle and holds it. I then do the same thing again one more time.

Any feedback or advice would be great. I will attempt anything at this point.

[slammin86]

Well for the time being I just lowered my IAC counts down from 60ish to 40ish. This gives me more air all over. It is just a bandaid for the time being and I would still like to hear some other opinions on this.

I think it is just the design of the fast92 tb that makes things behave like this.

[gagliano7]

Let me know what you find out because my truck with a 2004 5.3 1999 pcm in a 1992 chevy pickup headers, 212/218 voodoo cam, headers, cai, stock intake acts the same way. Truck runs perfect without a/c and free revving but when I have the a/c on pushing clutch in while driving the rpms drop like a rock and sometimes stalls and if I free rev with the a/c on same problem. If I let off the gas down a hill (with a/c off)for a few seconds and my rpms are around 2000 or more and I push in the clutch the revs will drop like a rock but it will never stall. Any other time rpms drop softly.

[lwrs10]

Question for both of you......do you have your rear o2 sensors unplugged?

[LSxpwrdZ]

A/C TM is the issue if all other idle parameters are in check.

[gagliano7]

I don't have rear 02's.They are disabled in tune.