i have a problem with my 89 tII everytime i turn on my AC after i drive for about 10 mins and come to a stop the idle will jump from around 2k and drop to almost stalling and rise back up i cleaned my BAC yesterday hoping to solve the problem but it didnt can anyone help me out i don't know what would cause it to do this

 

yeah i have a S4 vert and i have the same problem. if anyone can help id appreciate it alot. Thanks for your replys in advanced =D

 

i think it's something with the TPS, i have the problem with my 88 vert. A/C on, drops below idle, irratic idle

 

bypass air controle valve. i dont know where it is on your car. i dont know if its around the back or front or side. but . you can find out. you take it off. clean it with carb cleaner carefully. let it completely dry. and place it back on use a new gasket or some gasket maker. let it dry and then start up your car and try it.
also check your tps at idle. but most likely its your bacv

 

I am having a similar problem just in reverse. My idle is high with the ac off and perfect with it on. What could this be?

 

i took off my BAC and cleaned it and put it back on with gasket maker i dont know to much about the TPS so i don't know if i can adjust it if it needs it

 

after cleaning the BAC i noticed the problem sort of went away alittle it made it easier to stop the jumping idle by turning off the AC and hit the gas then it idles like normal but didnt solve it because it starts again after the AC is back on if i just cruise around and dont get on it it sometimes don't do it but if i get on it it starts idling funny i'm leading towards the TPS now any other thoughts

 

you should all try cleaning the throttle body, plates and everything in the intake, make sure the BAC is still functioning though that could be the problem, I had the very same problem with ac on the idle was eratic, I did a throttle body cleaning and used a drip bottle to do the intake cleaning, there is a solution just for this or get some seafoam, doing the cleaning completly eliminated my problem