ok guys i have a problem when the car is fully warmed up it idles at around 600 without AC on and then its a little jumpy from there then if i turn the AC on the car will idle for about 6 seconds at 450 and then die any way to bring up the idle to around 900 ?
Thanks
TwEaK

 

do you still have the BAC valve? In the haynes manual it says to adjust it at the BAC valve on the turbo models. but when i intalled my turbo swap(s5 engine trany) the BAC valve had no adjustment screw like the manual showed, so mabey just the S4 BAC valves have the screws. I just removed the BAC valve and adjusted the idle with the set screw on t/b that controls the stop point of the main throttle plates. Mine idles rock solid at 750rpm now.
I dont think that your BAC valve is working because when the Ac turns on the valve should open and keep the idle steady, not drop down 200rpm. I could remove mine because i dont have A/c or P/s.
Some one correvt me if i am wrong

 

dont have a BAC valve theres a block off plate in its location ill try the idle screw on the TB ill have to do that now since everytime i get to school shuts off before the turbo timer can give it time to let the turbo cool down.
TwEaK

 

I think Zbrown is on to something There's only three places I know of to adjust the idle. The one is the Boost Guage/Pressure Sensor (on the pass side shock tower), the idle set screw on top of the throttle body, and then the Throttle Positioning Sensor (attached to the front side of the throttle body, where your MOP handle attaches).. Do a search for any, or even jsut check your FSM, it'll tell you how to adjust them.

I do agree wtih Zbrown about the BAC not working, I also believe that's what causes the idle to drop when the AC is turned on.. I honestly don't know though, as the AC was the first thing I removed on my engine, and ALL of that crap is removed now.

 

Without the BAC, you're going to have to adjust your idle mechanically (via the idle adjustment screw on the TB, or if none, by opening the throttle plates a bit somehow) to be a bit higher than the usual 750, if you want her to "live" when the A/C is on...

 

wayne's right, throttle bodie set screw, that'll do the trick

 

After removing all emmisions and setting the idle via the nut above the TB, I actually have a much steadier idle. I have it set to 1k right now. A little high, but leaves some room for error if I want to run the a/c.

 

Can this be done on a '88 NA? My BAC is probably bad and I would like to raise my idle a bit, what nut on the TB, are we talking about the cable?

Thanks.