Thread: Year 3 no cold idle, checklist help PLEASE!

Thanks GOOGLE! aac OR IACV, Same thing. So cleaning it won't exactly correct it? It worked just fine prior to the swap, car idled no problem. Why would it just stop working properly after the swap?

You might not have plugged it in? The gasket might have failed, the heater circuit might have failed? The hoses might be clogged?

I dunno...

But that's the first place I'd be looking.

How bout those IACV numbers I posted from realtime, 18/90%? Are those correct? What are they suppose to be? This I searched with no return.

It's plugged in

Those are pulse width modulation (PWM) numbers for the idle air control valve (IACV) which is distinctly different from the AAC (Auxiliary Air Control) valve. 18% at idle while warm is fine. It means the idle valve is letting in about 18% of the air that it possibly can flow. 90% while cold makes sense because the ECU is trying to get as much air in to keep the engine running, but it isn't enough. Hence the auxiliary air control valve.

Ah, this is beginning to make sense. And when I searched and returned on google, all I quickly saw was IACV/AAC assuming it was the same. That's my bad.

Is the AAC the valve under the intake runners, kinda shaped triangular with two hoses one out of each side? Under runners being on my highport, on the back of the motor...or technically the side of the motor firewall side.

Check out the last bundle of pics in this post by Pretty White.

http://www.sr20-forum.com/115448-post23.html

That's the Auxiliary Air Valve.






Apparently the IACV/AAC gets it's name because it's part of the same housing:


The Auxiliary Idle Air Control Valve is something else. Maybe goes by the accronym AIACV? I dunno... We have so many idle control valves that no one can keep them straight and no one calls them the same thing. =(

The auxiliary idle control valve works like this...

It is fully open when cold. Inside there is a bimetallic strip that slowly closes the valve as the unit warms up. The unit warms up with heat from the surrounding engine and intake air, but also is heated internally with an electric heater. That is why it has an electric pug on it. The ECU heats it when the engine is running so after about 3 minutes or so the valve is fully closed and the engine is warmed up by then, so no extra air is needed. This valve provides the extra air needed when the engine is cold to keep the idle speed high (1,500 - 2,000 rpm) to keep the engine from dying.

Yeah, I have my idle speed set starting off at -40c/2,500 rpm and slowly declining in rpm as temp increases. Even when warmed and no longer needing my foot, the laptop setting does nothing for idle control. I can set it at 4k for 70c and up and she just sits at 1,000.

Going to click that link...

Something isn't right there either.