Idle Stabilizer Valve Problems?
 

I have a 1989 964 with somee cold idle fluctuation issues. So I decided to clean the ISV. It was easy. I pulled the unit and hit it with some degreaser. Looks shiny so I reinstalled and plugged it back in. But now the car won't idle at all. I can get it to start and run. But if I take my foot off the gas pedal, it dies instantly. Any ideas? And what, exactly does this thing do? Can I bypass it?

I too had trouble with the ISV on my 993. Tried taking it off and cleaning with wd40. It Didn't work. I then took it out and soaked it in a small container of b-12 cleaner. Sea foam would work to but it's a bit $. Then swabbed the inner workings with q-tips. Let it dry. Installed and haven't had a stall since. Hope this helps.

Sorry for the poor description, but is the piece you can see inside, supposed to slide easily?
My car fluctuates just a little at idle, but when I pulled my valve off, there was hardly any gunk inside at all and I tried to move the inside bit, but it wouldn't move...

Yes. The inner "slanted" metal shaft should rotate smoothly so that it can open and close.

sounds like I need a new one...

Yes, you may need a new one. On my 993, I tried cleaning it and it moves freely, but the idle still fluctuates when cold for about 1 minute. I was told replacement will solve it. Before spending money for replacement (even though it does seem like yours is bad) make sure there are no vacuum leaks. This will give same symptoms.

I have ordered another... my motor is going back into the car tomorrow so I will change the valve when it arrives.. should be easy enough while the motor is in the car.

I started this thread. But it looks like we have two members with similar problems. Thanks very much for the replies. They are genuinely appreciated. Like mikedsilva, I also ended up ordering a new part. The old one, while shiny clean, was frozen nearly shut. Would not move at all. It was 25 yeas old so I didn't cry about it. Now the car idles mostly ok (I opened another thread for the other idle problem). I did notice how the air hose on the intake side fits awkwardly on the part and could be a source of vacuum leak. Something to be aware of when installing the part.