idling problems

my 93 vtec is not idling very well. It likes to drop down to 400 rpm almost stalling then go back up to about a thousand. It will only do this when is all the way warmed up. Sometimes it does stall. I think its a IAC (Idle air control). It also will start doing it if I turn on some accessories. So may be a voltage regulater?? Does anyone have any ideas. Does any one have this problem with their h22a??

any Ideas???

check your voltage, check your vacuum lines, and check your oil while you're at it.

if you remove the intake tube at the throttle body and look inside the T/B you will see a small port when the car is surging cover the port with your finger if it smooths out its the IAC if it doesnt it may also be a bad fast idle valve.

so if i stick my finger in their and it doesnt stop then then its a bad fast idle valve> and if it does stop will it do it ever again? or will the IAC somehow have do get fixed..???

so if i stick my finger in their and it doesnt stop then then its a bad fast idle valve> and if it does stop will it do it ever again? or will the IAC somehow have do get fixed..???

Basically the IAC is a controlled air valve since the butterfly is closed on start up the engine has to get more air to increase the rpm so the IAC wich is the hole in front of the butterfly opens up the passage to let more air go through when the engine is warmed up and the idle surges it could be caused by one of two thing the iac or the fast idle valve. To test the Iac cover the hole this stops the extra airflow past the butterfly and will cause the idle to stabbilize if it doesn't stop when you cover the hole then I would replace the fast idle valve. See the engine is trying to compensate for the excess air flow and can't thats why it surges so no if you covered the hole and the engine still surges I would first check the coolant level then replace the fast idle valve. If you are dealing with an engine swap on the other hand there may be something altogether different that is going wrong.

oh okay..i just went and did that, and after like 3 or 4 covering ups of the hole it stopped..but u see i have a 94 del sol with a JDM h22a swap..the wierd thing is that the idling problem doesnt happen till its at night, when i am using my lights to see in the dark..(what does that sound like to you?) i also just got an gsr ecu (p72) to make my check engine light go away since i am not running an egr in the car..will that also make the butterfly mess up like u just said? please reply! thanks

The problem was I had bent exhaust valves on pistons 1 and 3.
Which means that I was losing compression in those cylinders and my vacum pressure was fluxuating causing the idle problem. :banghead: