Ever wonder what that vacuum actuated thing is at the side of a Toyota 1MZ/3MZ air intake is?

It controls a flap inside, to either disturb/redirect airflow for better mixing and reduction in intake valve noise, or to allow a direct unrestricted path at higher RPM's.


Here's a look at that flap:


Inside the intake plenum where it sits (note all the carbon buildup, especially around the PCV on the bottom:


The flaps don't end there. There's another one in this dual throttle body ES300 intake between the two throttle bodies:


Lesson learned while taking this apart: make sure you clean your car's air intake system, it can get really gummed up!

 

this is ACIS right? the 1UZ in the 1998 LS was one of the first (if not the first) toyotas to feature this i think, it's a pretty cool system and kind of sounds like vtec when it operates




if i correctly remember the literature, normally the valves stay shut to route air around the outside of the manifold because creating a longer intake path improves low rpm torque, but once a certain rpm and throttle position are reached they open up to make a more direct intake path improving high rpm power


this thread while largely pointless has a lot of great shots of the inner workings of the system

https://www.clublexus.com/forums/ls-...rude-hone.html