ISC/IAC valve
 

Mine does not appear to be working. The car starts and idles low until it warms up, then idles fine. I don't have A/C, so that is a non-issue. Is there any problem with just leaving it non-functioning? Does it fail in the closed state? Or, can I just remove it and install a block off plate over the opening and bypass the coolant lines? Has anyone done this? I know the guys running mustang TBs dont have the valve. I just cant see spending $250 for something that may not be necessary on my car.

My car idled like ass with a non-functioning one, so I bought a new, off-brand one that helped tremendously.

You might be okay without it if you jack up the base idle?

I by-passed the coolant line on mine. Not because it wasn't working, but because I didn't need the TB warmed up in my climate. Up your idle a bit and you should be OK.

Or you can always pic up a used TB with working sensors, I may have one around for that matter.

I had a spare that I forgot about that had a good ISC valve that I swapped over to my auto TB the other day. That problem is solved, but the one about my car missing is still not. :(

Just switched mine out. My car was throwing code 34, which is the ISC. Take an ohmmeter and measure across the contacts for it, should be 12 ohms. The ICV that I got sucked, so I will be getting a brand new one. Just check to see if it is throwing code, that thing is expensive as hell brand new.

Rumor has it those coolant lines are for deicing not so much warming, and icing can occur well above freezing. Just a thought.