idle fine(1000rpm)when cold.engine warms up idle lowers(500)

[takem2church]

ok i have noticed myidle being low since abotu 2 months ago. i have invested into oxygen sensors hoping that that will fix it. they are not here yet however i have noticed that in the morning when i start my car and my engine is not yet heated up that my idle is fine. when my engine warms up it gets lower and lower and at stop lights it will sink down to 500 then jump back up to 1000 then sink down to 500.... i am not sure what the problem is and if the oxygen sensors will fix this or now. maybe its my alternator? does anybody have any ideas? also my idle drops even more when i turn on my rear defroster if that helps. thanks a lot guys!

[MSS325]

Do a search on ICV or "idle control valve". There's tons of info about how to clean it. This will usually fix a jumpy idle.

[martin01]

yup, the ICV will cause most of your idle problems

[Mr.M]

Yeah, ICV. I just cleaned mine and am going to do a write up on it for the M42.

[takem2church]

yeah see i would say that too, but would that explain why it runs fine when its cold? i have no idea about the ivc so im not sure but im assuming that it would cause it to always idle shitty not just when its hot

[adriver]

Mine was doing that after it rained heavy, and then only when it gets real cold here (Tx, real cold is like low 40s or lower) its gotten warmer and it hasnt done it anymore, I just figured it was the weather. Im interested in what you find out.
EDIT: it was also shortly after installing my CAI, but how long would it take for my engine to get used to?

[MSS325]

yeah see i would say that too, but would that explain why it runs fine when its cold? i have no idea about the ivc so im not sure but im assuming that it would cause it to always idle shitty not just when its hot

The ICV is just a gate that allows air to bypass the throttle body when the TB is closed. They become quite dirty over time. The gate in mine would barely move.
After cleaning, it moved freely. Also 1000 rpm seems a bit high. You should be around 700-750. Electrical load can cause some fluctuation but not much.

I would clean the ICV first but if you have doubts have your battery checked too.