Resigned to replacing my Idle Speed Air Valve (ISAV), I tried to take it apart to understand its inner workings and see how it might be adjustable, as mentioned by dpetryk:



Four hacksawing episodes later, and it still didn't fully come apart.

It's a well-built little gadget. My only useful observation was that the plunger-valve was dirtier than I expected after cleaning it with nearly a full can of Brakleen three weeks ago.

Before I sawed it apart, I connected the ISAV with some spare wires to my model railroad transformer, which outputs up to 14 volts with no load. When connected up, it took "full throttle" on the transformer to fully close the ISAV plunger. My VOM indicated 4.6 volts. This may be a totally incorrect method for testing the ISAV, but I wasn't impressed by the results...so, out came the hacksaw.

As for adjustability, I did see a threaded insert underneath the plastic cap (upper left in photo). This probably adjusts the spring seat and its force, but I could figure out how to move it.