I'm very sorry for my first post here to be like this, but I am in much need of help. So here it goes. Ok, it's a 2000 civic si, and here's what it's doing: The idle will move up and down when sitting, sometimes it will even sit at normal level for a bit and then move up and then down. Then the "CHECK" light came on. I took it to autozone and it came back as Idle System Malfunction. Anyone have any idea as to what i should check out/replace first by any chance? Any and all input is more than welcome. Thanks guys.


steve

 

Check out the idle air control valve (IACV) which is a little motorized thing mounted at the throttle body. Make sure it's electrical plug is clean & tight. Sometimes they need to get cleaned out with throttlebody cleaner, sometimes they're just messed up & that won't work. Search for IACV or IAC valve for some more detail...

 

i cleaned out the little screen and it seems to be better now . . . . but on another note, should there be a humming coming from the intake at idle? thanks again.

 

The humming noise might be the IACV?? I don't notice mine making noise, but it's a different engine & I haven't gone out of my way to listen for it.

 

i found the main problem, there was a small tube that needed to be connected to the underside of the intake manifold, that being connected, and the screen in the IAC being cleaned out now, the car is idling like a million bucks. That's for the help!