I was doing some research after learning that my IACV was making noise and am still not completely clear...
It seems that the "humming" noise coming from my IACV is normal, but it does not shut off at all when the car is turned to the "on" position. It can be on for hours and the humming still goes. I have read around and it seems like it should "hum" or "buzz" for a few seconds or so and stop, and if I doesnt, it could be an IACV going bad. I replaced mine with an autozone "denso" part, but the first one I got there was defective and I'm wondering if this one is too.
My car is a 92 LX auto and is running a bit on the rough side. I can also turn my idle screw all the way in tight, and the car will not idle below ~850rpm when warmed up. Right now I have the base idle and timing set properly with a recent tune-up.

...what are everyone's thoughts on this continuous IACV "humming"?????

 

If you have your idle set screw turned all the way in and your still at 850rpm, your IACV is stuck open. Try getting an OEM one from a junked 90-97 Accord, clean it before you install it and see if it works any better.

 

So...I found two used IAC valves and cleaned them out. After attatching the electrical connector to all three found that they all made the same continuous "buzzing" noise. Then I looked into each valve as they were being powered and saw that 2 out of 3 valves were doing the same thing... The valve pintle would quickly "jerk" backward slightly and then immediately ease back closed. Although one of them would still make the same noise when attatched, the pintle would not move.
At a glance, it looks like the "buzzing" noise is a normal function of the IACV... or could all 3 of the valves be bad???...maybe just one worse off than the other 2. Here's a drawn-out video of whats happening to 2 out of 3 of them....hopefully this works...

http://www.youtube.com/watch?v=t9J2k...ature=youtu.be

***Also, I read something about the possibility of my power steering pressure switch going bad and steadily sending a signal for my IACV to stay open to compensate for the load. This sounds feasible to me, but I can't find any info at all about the switch in my haynes manual.

 

It is a possibility that some other sensor is causing your ECU to send a constant signal to the IAC valve. However, the check engine light would usually be on indicating an issue with that sensor. It could also be a short in the wiring harness or an issue with the ECU itself.

Is your check engine light on?

 

I do not have any codes showing up, and my ecu seems to work. It lights up briefly after i turn the ignition "on"...and when I disconnect my ICAV it shows the right code...