There's some debate in the automotive maintenance world about whether cleaning a throttle body on any vehicle without completely removing it from the engine actually does more harm than good. With my wife's 2004 RX330 now pushing 95,000 miles yet still running well, I'm considering cleaning the throttle body without removing it. For those of you who have done this, did the cleaning process cause your engine to idle smoother and quieter? That is the typical result of a successful throttle body cleaning judging from the vehicles that I have cleaned in the past. I've removed the air filter housing, held the throttle plates open with one hand while spraying a can of throttle body cleaner with the other hand, wiped up as much of the carbon-dissovled goo as I could reach with a clean rag, and then reinstalled the air filter housing and taken the vehicle out for a test drive. On my 1999 Dodge Ram just yesterday, it was a piece of cake and worked like a charm - a 15-minute procedure at most....

I assume there is an O-ring gasket on the RX330 that fits between the air filter housing hose and the front of the throttle body. For those that have cleaned your throttle body, can you confirm that there is indeed an O-ring? Did you install a new one? And what exactly did you wind up having to remove to gain access to the throttle body in order to clean it?


NOTE: In the title of this post, I meant to type "2004", not "3004". Sorry. I wanted to correct it, but don't know how to get to the Title Line in order to do so....

This recent discussion from CL does not directly answer your question but has some related info:

http://www.clublexus.com/forums/rx-second-...-body-iacv.html

RX in NC,
The correct and complete way to clean a throttle body is to remove it from the engine so you can clean it thoroughly. I just cleaned my 2005 RX330's throttle body last Friday. 2004 and 2005 RX330's have the same throttle body. There's a round gasket with "wire screen" inside that I replaced, although, I think the old one is still reusable. This is the mounting gasket between the throttle body and where it is mounted. There are four mounting bolts that you need to remove to get the throttle body out. As soon as you unbolt the throttle body from where it is mounted, you will expose the gasket I'm talking about. I haven't seen this kind of gasket before because of the wire mesh in the middle.

The car idles smoother after cleaning. It's back to normal at 750 RPM from almost 500 RPM before cleaning.