My 2018 Lexus RC300 with 9K miles and I are subscribing to this thread.

Appears that I am suffering the same symptons. Thanks to Flash5 for pointing me in this direction.

I first noticed this issue some time ago when I added my invidia midpipe to my PPE catless downpipe, TTI turbo muffler delete and Injen intake. I was still running my stock axle backs so I thought the issue was related to bottle necking from the stock axle backs. It only was slightly noticeable above 3k rpms but it was pretty subtle but I attributed it to my stock axle backs.

I'll be ordering 25819-0w010 and 25760-36051 today!


BTW, did anyone else get a P0001 CEL code?

 

Some of the videos aren't available anymore but I uploaded a vid/sound clip of mine. You can hear the car struggling. Is this similar sounding to your guys issue?

https://i.imgur.com/3ORgERx.mp4

 

Was the replacement hose on the outside or inside line?

I got my replacement parts today. Began installing them, took one bolt off the original vacuum regulator. The inside bolt was a pain in the *** and my lower back started to tighten up...so I disconnected the lines and the plug and reinstalled the screw and left it. Terrible I know...I ended up installing the new regulator with the lines and plug installed and zip tied it to the front. Not a lot of room to pull it forward do to the plug wire being so short.

Pretty mad at myself for leaving the old one in but my back was really getting to me. I figured this was a good alternative to at least test if this will fix my issue. I did not install the new hose yet as I don't know if it's the outside line or inside line. I hope it's the easier of the two.

 

Ah. No. Re read the service bulletin. It’s the easy one!

 

GREAT NEWS!

New volume control regulator and hose fixed my problem! I can now accelerate smoothly without feeling like I'm tapping the pedal.

BAD NEWS
P0001 code came up...I reset it, I feel like it comes up every few miles. Car is not my daily driver so I'm garaging it till the weekend when I can poke around. If anyone has any advice please feel free to message me. If someone can point me towards where the fuel volume regulator is, that would be great lol.

 

How difficult was it changing the hose? I'm on my 4th regulator now but I've never swapped out the hose

 

Pretty easy.

 

CEL Gone. Back to normal operating procedures

 

[QUOTE=Quillo;10637997]Mine started failing this weekend after a roundtrip from Tucson, AZ to Sedona AZ (around 400mi trip), glad i found this post ! I have put 37,800 miles in it. I already scheduled an appointment with my Lexus dealership rep. and shared with them this post for reference, as they told me they dont have any is200t turbo related issues recorded from other customers.
Interesting in my case i took the car this morning for a drive and everything was smooth, so i guess the issue is heat related or it just started to fail and after the engine cools it starts working as normal.

i have an injen intake and ARK Grip Catback since 27k.

 

[QUOTE=luilly3d;10790982]If you ever have to take it in for this issue, remove your intake. There's also a service bulletin you can show them. Even if they don't have boost leak issues recorded with their customers, they still have to fulfill the orders in a service bulletin.

 

[QUOTE=luilly3d;10790982]Update:
Took it to the dealership this morning and for my surprise, after sharing this post and the Technical Serv Info Bulletin from Lexus, they ordered the part yesterday and will be changing it today. The serv tech said they need to raise temperature to certain level where they know will start failing, so they have I guess further instructions on how to replicate and diagnose the issue.

For those who are interested or want a copy of the Lexus Technical Info Bulletin, se attached.

 

[QUOTE=luilly3d;10791581]This is actually the outdated one. The new one also changes the hosing.

 

[QUOTE=Flash5;10791740]Ohh, well that’s even better!

Update:
Got my car back already, no more weird boost sound, back to normal. Thanks everyone who has contributed in this post for the great information that makes it easier for those who, like me, discovered the issue recently.

Be safe everyone!

 

@luilly3d
Lexus TSB IS 300 .pdf

 

You were my spirit animal guide when I was trying to figure this crap out lol. No one on the RC side knew anything about this. I find myself posting more over here than there which is still appropriate since I had a 2015 IS250 F Sport lol