99 civic obdI. run great. d16y8 stock
ok so i searched this and this is really not a major deal for me since i can just adjust the iacv duty cycle in hondata to fix this but thats more of a band-aid and i want to fix it for good. i have been running like this for a year or two by now

but my idle is perfect when cold and iacv seems to work. but once engine is fully warm and i start to drive and come to a stoplight or slow down and let go of the throttle the idle goes down to like 200rpm and then goes back up. a couple times in the winter it has stalled.
if i sit in the car and just watch the idle for some time it will do this over and over again.
like 800rpm then dips low to 200 then rises back up(assuming ecu sees it and send some juice to the iacv), then it is fine for about 30 seconds and then dips down again(ecu send voltage to iacv to fix it). Its pretty annoying.

Well I thought maybe i need to check iacv function. unplug iacv and car dies. so I raise the idle screw higher with iacv unplugged and start the car. this is obviously while car is warm and doesn't need the iacv to run the motor. I adjusted it pretty far out(more than normal on most cars) and then finally got it to idle at about 200-300 rpm. it will surge up and down though. I took the screw completly out and it was still idling at about 300 rpm.

So does anyone know what is causing this. I am thinking something is clogged or plugged up with carbon. some passage way for the air. I dont know much about idle because i never had idle problems like this before.

I know its something so simple. iacv related or a air passage. i just need to know which one

 

noone

 

search cleaning your FITV - Fast Idle Thermo Valve

 

already happened

 

clean both the iacv and the fitv and the throttle body with carb cleaner

 

x2 and make sure the fitv is adjusted properly.

I know this link refers to an integra, but the procedure(s) should be the same for your vehicle.

http://www.team-integra.net/forum/19...iming-adj.html

 

there is no fitv on 99 civic's
that stuff is old school

and i cleaned the iacv and the throttle body with carb cleaner. even sprayed into the holes going into the iacv and up on top of the tb

i might just have to take it apart i guess.

but i know someone has had a similar problem and fixed it before