1KZTE VSV / Idle Up Actuator question

[dodido]

I'm hoping that someone can help explain how the idle up works in my 1999 Prado, 1KZTE...

There are two VSV's connected to the top of the Idle Up Actuator: VSV No.1 and VSV No. 2. The Idle Up Actuator has two ports on the top. I believe the Idle Up Actuator controls the small butterfly in the venturi.

My theory: I am assuming one of the VSVs opens at the same time that the EGR valve opens, which sends the vacuum to one of the ports on the the Idle Up Actuator, resulting in the small butterfly either partially or fully closing (since the engine is now getting recirculated exhaust from the EGR valve). I am also assuming the other VSV opens as the engine is turning off, sending the vacuum to the other port on the Idle Up Actuator, once again either partially or fully closing the small butterfly for a smoother shutdown.

Can anyone clarify the above operation for me? How does the Idle Up Acutator work with two input ports? Do both ports ever get vaccum at the same time, or is each port independent? Which VSV is responsible for which function? When is the small butterfly fully closed, and when is it partially closed? Is the small butterfly open in the absence of vacuum to the Idle Up Actuator?

See below for schematic. Thank you!

 

[dodido]

As luck would have it, I did some digging around this morning in a Denso Injection Pump manual and I think I found my answer.

Although the below doesn't show either of the VSVs directly linked to the EGR system, I wonder if "Condition 2" below (normal driving) is when the EGR valve is open, which is why the small butterfly is partially closed since the exhaust gases are being recirculated. Can anyone confirm this? I added the EGR section as well for reference.