hey guys hoping someone can point me in the right direction of my problem...

just had cc306 cam installed and a pcmforless tune for it in my 93 ta.. runs ok, idles ok, seems way rich at idle for sure but none the less runs and drives ok, UNTIL you turn the ac on... turn the ac on at idle and car stalls. since the cam and tune were installed the idle up feature when the ac is turned on doesn't seem to be happening. i did hook up a scan tool and see the following:

learned idle pos 39 steps
throttle sensor .72 volts
iac position 77 steps(floats around in the 70's at idle no ac)
iac position jumps to 160 when ac turns on, yet idle does not pickup

currently have the tb off the car, cleaned the iac and have some oil on it right now... waiting to reinstall as soon as i'm off work. just not sure if this is going to fix the problem, since it didn't seem to be stuck before i took it in for the cam install.

any help greatly appreciated!

 

forgot to mention, i also checked the iac w/ an ohm meter... it tested 51-53 ohms across both sets of terminals, which i believe is supposed to mean it's good.

 

are you using stock throttle body or aftermarket?
I had same issue, my cam is milder, 218/224. I'm also using after market TB.

Factory TB has an fixed bypass drilled hole in throttle body (bypassing IAC) This should maintain fixed idle. IAC will adjust to compensate for load changes ie; AC

Max opening for IAC is 160 counts, you verified with scanner its trying to maintain by opening all the way. My cam needed more air to idle correctly with AC on, especially in open loop. A few ways people have fixed it, enlarging fixed hole in TB, drilling a hole in butter fly blades, or adjusting the stop screw to crack butterfly blades a litte.

I corrected mine by enlarging fixed orifice a little, and barely ajusting stop screw to crack blades a little, if you adjust blades to much, you have to reajdust your tps.

 

i am running aftermarket 52mm tb. the shop that did the cam already adjusted the blades open a little bit... what area are u drilling out/enlarging on tb ? i've seen this mentioned several places, but since it's mainly old posts the picturesd are no longer hosted.

 

I have a couple good links, when I get home tonight i'll post, or pm me your e-mail (limited use here at work).

My car only had the idle problem on open loop mode, once it went to closed loop the car idled fine, AC on or off. If it was getting enough air at closed loop without modification to TB, what the heck is going on at open loop?

I played with opened loop AFR, timing and IAC settings, ended up just modding the TB and all is good

 

I also had to drill out the hole in my tb to get the idle correct with the gm847 camshaft.

 

i found this link... is this what u guys did:

http://www.hashmarks.com/techtips/throttle_body_mod.htm

did u use the copper tubing or just drill the hole?

 

Thats pretty much it; one person machined small pieces of alumunim to fit the notches. I just used jb weld to fill the notches, no copper tubing, sanded down the jb to the same contour works perfect. I also used 11/64 drill.

 

i got lucky my tb is a older edelbrock/bbk version and its iac port did not dump to the each of the venturis like in the link i posted. mine just had a hole that dumped to the iac port of the manifold, BUT with no bypass hole, so all i had to do was drill a 11/64 bypass hole(no copper, no jb weld needed to block it from going into the main ports of the manifold), and elongated the holes in the tps so i could rotate it a bit to get it closer to .50 volts... its now reading .56 volts, and the iac is commanding 18 at idle no air, and around 80 at idle w/ air on. it idles, starts, much better now, and even seems to run a bit stronger. hard to believe such minor things caused such major issues. it still takes a long time to go into closed loop, but it also runs very cool, i'm not seeing it get over 180 and fan 1 is only somewhere around 170 it seems... so that plus the 93's not having heated o2's is probably why taking so long to hit closed loop.

thx a bunch for the help guys... i may try changing o2's out and see if it improves some more... they are 17+ years old, even if they do only have 27k miles on them.

 

I did the heated O2 conversion, definitily a must with long tubes,

The sooner we can get our 93's out of open loop into closed loop the better, Really helps on driveabilty.

Do Google search on O2 conversion.