I recently changed the majority of my vacuum hoses, but there remains one portion of the vacuum system that I simply cannot find in the car. I have circled in green in the vacuum diagram.
It seems obvious from the diagram, but I don't see it. Does anyone know where the heck this is located?

 

Near the fuel tank? That's my best guess.

 

that is consistent with post #1 of this thread which says charcoal canister is located above the fuel tank ...

https://www.clublexus.com/forums/sc4...-canister.html

 

Charcoal canister? --- hmnnn. I was thinking it was part of a IAC valve system like in this LS430 diagram. The shapes match. The location even matches the apparent location in the SC430 vacuum diagram, but I don't see anything like that in my SC430.

 

Mystery partially solved. Found where and what that vacuum canister lies in GS430 documentation.
It is not near the fuel tank and it is not the charcoal canister.

It is under the intake manifold on the GS430. Throttle body is in front of it. Maybe that's why I could not see it looking around the engine compartment.

This mysterious component is the acoustic control induction system (ACIS), a completely different system and purpose. It increases air intake length during lower RPM's.

BTW, Fuel vapor purge is via the VSV system atop the engine. That is the easy to find one on the driver's side (left) with the green test port.




BUT hold on. This pict from when I cleaned my throttle body. I don't see it.

So, the mystery is not quite solved on the SC430

 

I 'm thinking I may have to follow tubing from ACIS activator at rear of engine to find this this. Nobody seems to know where it is, let alone that it exists.
Question is whether I can see the ACIS activator from the tight space in front of the firewall.

 

Well, heck. No wonder you can't see it. Here it is from a GS430 thread. https://www.clublexus.com/forums/gs-...ing-valve.html

It is totally buried under the intake manifold along with the starter.

 

Nice detective work there Seattle SCone.

 

Found this absolutely fantastic video. It's about changing the starter, but also shows the vacuum component.
This is also one of the best DIY videos I have ever seen!

 

Dang, that is really involved. That's a lot of electrical connections too.

 

After watching him a few times, the process seems easier and easier. Still, not going to take that much apart for preventive maintenance.
But he really does get you stoked for replacing the starter.

 

Wow, that's not for me. This job is for my mechanic. One good thing is the SC starter rarely goes bad.

 

I had to change my VSV valve last year and it seemed like a massive job just to get to one screw, but it was not that bad. You can leave the throttle body conected so no fluid lose.
Just took my time and lots of photos. It's amazing how much crap builds up under there.

 

Respect getting that done yourself!

 

Agreed! Seems like a design flaw as this area is inaccessible to clean out said crap. I've been concerned about this for decades with my 2001 Tundra and now share the concern with my SC. It's one more reason to keep the engine cover in place (a lot of members like to remove them).

While I haven't had to remove a manifold yet, it seems tedious, yet doable for the home mechanic with good tools, hands and patience.