IDLE DROP! please help

[kcunanan]

hey guys im new to the whole 240 scene and all. so i bought a 1991 240sx coupe, and it was bogging out on me and the idle would keep on dropping. So i did a little research and read that it might be the IACV so after reading a few posts i cleaned it out and started up the car and it still kept on happening. So then i read some more and some were saying it could be the throttle body, so after reading again i cleaned it out and it the problem stopped for like a week. But then lastnight as i parked in my neighborhood the problem started again. so im not sure what to do now, its not consistent like it used to be. every once and a while the rpms will drop on me. i dont know what the problem could be! please help out a fellow 240 owner! also ive adjusted the rpms after i cleaned out both the IACV and the throttle body.

[racepar1]

EXACTLY where was this "IACV" valve that you cleaned? The one under the mani, on top of the plentum? Or the valve assembly on the back of the manifold? I ask because oftentimes "IACV" is used incorrectly.

[kcunanan]

in the back right of the engine if that helps. sorry i dont know what or where the plentum is. im very new to this :/ but it was pretty hard to get to it.
http://i3.photobucket.com/albums/y56/codyscool/IMG_3437.jpg

[racepar1]

in the back right of the engine if that helps. sorry i dont know what or where the plentum is. im very new to this :/ but it was pretty hard to get to it.
http://i3.photobucket.com/albums/y56/codyscool/IMG_3437.jpg

The valve with the red connector is the AAC valve, the purple connector is the FICD valve. The AAC valve does most of the idle control. The FICD valve opens up for fast idle when the engine is cold or when there is a heavy load on it at idle (A/C, high P/S pressure, etc...). The IACV valve is on the plentum under the manifold runners and opens when the engine initially comes down to idle to keep the idle from dipping when the throttle is closed suddenly. The plentum is the chamber behind the throttlebody before the air is split into the individual cylinder runners.

For your issue I would start by cleaning all the connectors and crimping the female sides a little tighter with a pick or tiny screwdriver. The issue sounds intermittent. A little di-electric grease wouldn't hurt either. I had a similar issue and it was a dirty/loose connector on my IACV valve.

[kcunanan]

ahhhhh so that means i gotta take it apart again damn it LOL i hated taking that thing out

[racepar1]

You don't need to take anything apart to clean the electrical connectors.

How did you clean that valve assembly? Did you COMPLETELY dis-assemble it and clean it THOROUGHLY?