The fast idle thermal valve is directly underneath the TB. Helms manual says to test it like so.
Remove the intake air duct from TB, start the engine and let it idle, and cover the lower port of the throttle body. If engine speed drops, check coolant level and for air in the cooling system. If all is okay replace the fast idle thermo valve.
If engine speed did not drop cover the upper port of the TB, if then it does drop then adjust the idle speed. If it still does not drop check for vacuum leakes and make sure the throttle valve is completely closed.
Shop manuals are your friend. I would definitely suggest getting a Helms if you are going to work on your car. You think we know this stuff off the top of our heads? Ha!
I pulled a code 45 (too rich/too lean) and a code 14 (electronic air control) on my friends 00 Civic Si
Last night I pulled off the IACV and cleaned it out and re-installed it. Also reset the ECU. The CEL came on, and I was expecting to see the code 45, but it was the code 14!?! The code 45 is gone! I think the ECU is confused... is it normal to fix one thing and have it fix the wrong code? The IACV doesn't do anything with the fuel system, just the idle, right? And after cleaning it out, the car idles just fine now. So now the car is acting fine, the IACV is clean, but I'm pulling a code 14... I don't get it. Any suggestions?