SR20DET idle air control function.. how it works? upgrades?

[cartel]

cars running but looks like the IAC is allowing more air in than is needed ...and i dont have "stock" plumbing to see what is normally there if there is some restriction that nissan has put in the feed system.. the "idle" screw thats on the IAC doent do anything-- i can move it- its clean internally - i removed and tested it and the plunger blocks carb cleaner when unpowered and i can see the plunger move with a power probe and then the carb cleaner moves to another passage within it.. so it appears to be working as far as a test..

from what i gather the iac is supposed to get pulled closed from intake vacuum when starting- then motor opens as needed to control idle based on ecu tune. we can make idle go up with ecu but not below 1100.. so doesnt appear to be fully closing- and engine has vacuum- i will do a smoke test on intake to see if any leaks - thats next..
if i cant figure out the stock system im thinking the driftmotion IAC with the supra checkvalve might be the way to go as it uses a simple ford IAC and a adapter and check valve for boost .. as this isnt much more than a new nissan iac ..

any suggestions or other options?
i can put a restriction on the feed to the iac and slow the rpm down but trying to understand how its supposed to work..

[icehouse]

There is an idle screw on the throttle body. Sounds like it's way to high. Slow idle with throttle body screw to slightly lower then you want and use the ecu to raise it with the IAC.

[cartel]

I have throttle stop on tbody with a gap already. plus I need to add a Tiny bit of preload on it as I can feel the blade stick now...
and loosened the cable for now just to make sure.. can't get below 1100 with timing set proper unless I restrict air on inlet to IAC.

[cartel]

well just did smoke test. no leaks.. if I unplug Iac feed smoke comes out but assuming what I found is true its supposed to be open until running..

I would sure prefer a iac just be closed and only open when told to..

[icehouse]

If you block the IAC what is the idle?

[cartel]

it stalls-- at the current throttle blade opening.. what ive read is all idle air is supposed to go thru the IAC and not use the butterfly opening.. so maybe its defective.. its a $150 part to test and at that point i think id rather a ford IAC with the supra boost valve ..ive got another s14 Iac for a sr20 but not a s13 one..
ideally id like to swap one out to test which at this point would be the best solution- sucks as last week before i had this running i HAD a sr20 swapped 240sx that i just sold.. UGH..

but right now it idles fine just fast and with a rubber hose stuck within the feed line i can get idle to 800 -- thats definitely not the ideal solution tho.

its really hard to test-- it looks like its closed and sealed but maybe its not opening only from vacuum- not sure how can test that--

[Three B's Racing]

If you've readjusted that stop for the throttle body's butterfly it changes the voltage at idle on the throttle position sensor (TPS) so you would have to reset that. Check the fast idle cam that it is correctly set cold and hot. This is assuming this is a S14 motor.

[cartel]

fast idle cam?

link g4+ standalone ecu.. reset tps at start.

giving up on stock iac. gonna try mustang one that driftmotion uses

[Three B's Racing]

fast idle cam?

link g4+ standalone ecu.. reset tps at start.

giving up on stock iac. gonna try mustang one that driftmotion uses

Yes, Fast Idle cam typically found on the S14/S15 engines throttle body. Sounds like you have an S13 as they didn't have this.

[cartel]

one engine has a 70mm aftermarket throttle body so not nissan