Thread: IACV/Air Regulators for Everyone

^You have pics of what you speak of? No screw? That think would be wide open.

If you drive your car in colder weather you are going to want to keep yours. Without it you will have to hold your idle up with your throttle pedal, until the car warms up. Otherwise the car will stall out.

Im not sure about removing the IAA Unit (Idle Air Adjusting). Most people call this unit the IACV.. The IAA unit has 3 critical components: IACV/AAC valve, IACV/FICD solenoid & the Idle Adjustment Screw.
The IACV/AAC valve (auxillary air control valve) controls your idle and modifies air flow as determined by the ECU using pulse signals under certain conditions: engine load, warming up, decelleration, electrical load, etc.
The IACV/FICD solenoid turns on the fans & increases the idle when the Air Conditioning is turned on.
The Idle Adjustment Screw allows adjustment of the idle when engine is in timing mode (kinda important for tuning the car)..

Heres a picture of the IAA unit (also known as the IACV):
The round cylinder with the built-in plug is the AAC portion.
The solenoid with the wired plug is the FICD portion.
The Idle Adjustment Screw is on top.



The newer unit has a spring inside to reduce clogging (old style units dont have the spring; make sure your new unit has the spring):




The IACV/Air Regulator is located under the Intake mani on the passenger side. I would think that removing it would cause a very high idle unless the air path are completely clamped or blocked off. But once removed & blocked would require holding the gas pedal during warmup on cold days as discussed earlier. Down south this would probably not cause much of a problem. But Northern climates would be a royal PITA IMHO during winter starts.. Heres a picture of the Air Regulator:




Reading this thread, it appears that some people are using the term IACV to describe 2 different units. Hope this helps for clarity..

I normally call the first unit: the IACV and the second unit: the Air Regulator..

does anyone run a non iacv setup? i cant even pinch off my iacv hose without the engine stalling, cold or warm it still stalls, guess i couldnt run a non iacv setup

I've pretty much removed all of the vacuum lines on my NX except for the one that runs the fpr. There may be one more line - possibly going to the IACV - but I don't think so. I was having such terrible idling problems that I just bypassed everything that wasn't necessary.

So my IACV is still there, but is capped off. Since I've done that, it idles at the same all the time - when I first start it I have to feather the gas for a couple seconds tops and then it's good. In the winter I have to for a bit longer, but not in an annoying amount.

Since I've done this though, my idle has been very stable, and I've had less hesitation and gotten a bit better gas mileage (I've done several other improvements as well - so that may not all be because of just this).

did you capping off the iacv require you to have more input from the aac valve? or the idle screw on the throttle body.

as of right now i have tried to deligate a equal ammount of idle responsibility from the throttle idle screw and the aac valve, i have the throttle body almost shut and the aac valve open enough to get it to idle at a ''low'' 1200rpm (which is low for my car) BUT i still get a slightly bouncy idle, slightly up and down maybe 100rpm still annoying but more stable.


not sure if i would have to input more air from the aac valve to make up for the iacv from being capped off

Scotty you got it. I was under the impression that IACV/Air Regulator was the Auxiliary Air Control Valve (AAC).

If my car starts having bad idle issues, I just might cap it all off. That would help prevent an unfamiliar person from being able to drive it haha.

We've all experience those bad idle issues. They can be a bear to discover source & to resolve.
Once, I cleaned the throttle body & had idle issues for months after...

As for the vacuum lines, Ive also removed the vacuum tree in my NX and eliminated most of the vacuum lines.

The IACV (IAA) dont have any vacuum lines (solenoid controlled).
The Air Regulator has 2 hoses (one on each side). So you are probably good.



Good... The pictures did help to clarify the IACV terminology...
Nissan screwed up with naming these sensors, but used the IACV to link all the related Idle Air components.
Took me a while to get these idle component function terminology straight when fixing my idle problems...

^DC, do you know when they started making the units with springs? I was under the impression that all my IAA Unit (Idle Air Adjusting) were from the old style. The one I pulled off my UK 10.1 motor has a spring in it. I'm about to go through the cleaning steps we talked about on the phone.

P.S. +rep for post #23.

Scotty once again thank you!!!

When I was installing my Avenir W11, I switched out the IACV from my low port onto the Avenir.

So they must have switched to the new IACV on Roller Rockers?

On the left is Avenir, on the right is 99 SE-L Low Port