On my Civic, the manual states to disconnect the IACV(EACV) at full temp with ALL accessories off, etc. Headlights off, etc. Then adjust the idle speed screw to the proper spec. Like around 400 RPM for my car. Once that is done, reconnect the IACV. It should now be around 600-700 depending on the sub-model Civic you own. Lastly, there are some checks on the idle RPM speed with different loads on the engine, headlights on , etc.
I have yet to do this, but may eventually after I clean the IACV I have/replace the gasket and hunt for any other idle issues. Instead of a fast idle valve on the VX, unlike other Civics, my car has a vacuum control 'box' that may/may not be attributing to the idle symptoms that I'm having. Aside from air in the cooling system, EGR or fuel system related issues, that is what affects idle for these cars.
I have yet to do this, but may eventually after I clean the IACV I have/replace the gasket and hunt for any other idle issues. Instead of a fast idle valve on the VX, unlike other Civics, my car has a vacuum control 'box' that may/may not be attributing to the idle symptoms that I'm having. Aside from air in the cooling system, EGR or fuel system related issues, that is what affects idle for these cars.