I'm a long time Fiat owner, but new forum poster. I have an 82 Fiat, which I have had for about 16 years. The idle has been poor during a warm start up for quite a while, but has been getting worse. I've checked the fuel injection system using a manual, but all seems well. It's almost like vapor lock on an old carburetter system. Cold start is fine, but the car never goes to a very high idle (above 1200rpm). The auxiliary air valve was replaced 3 or 4 years ago and appears to be working. I put it in the freezer for 10 minutes and the valve opened.

The car has 112,000 miles on it and runs well otherwise. Any ideas?

Well, I think I have solved my own problem. After doing some more research on the fuel injections system and Aux. Air Valve in particular, I found the valve can be adjusted. I took out the valve yesterday when it was at ambient temp. The valve was completely closed. I loosened the adjusting nut and moved it so the valve was open slightly. Reinstalled everything and now I have a fast idle at start-up and when it was warm, it did not die.

Apparently these valves may not be adjusted properly, this was a replacement unit. If you have my problem, try this fix.