During the week, my 99RX 130k miles died twice as it could not hold idle. MPG had also moved down to 18.5.

I bought O2 safe carb cleaner and removed the intake. Removed the valve actuator and felt the sticky movement of the shaft. Cleaned it out with the cleaner, followed by couple of blasts of compressed air.

After reassembling, it took couple of attempts to start. Took RX for a spin and things look good. The new average is 21mpg ,,,, no traffic ... so come monday it will drop below 20's. Gas pedal feel is also different (better).

Total time less than 20 minutes.

Salim

 

Great job Salim.

I too did a clean-up 2 days ago. 00RX 116k.
Started to get rough idle at stops in Drive.
Soaked the IAC down with throttle body cleaner and used a toothbrush for the throttle plate.
All is good after. Except for the billowing smoke once I started it. Cleared up after a test drive.

Did you take the IAC motor out completely?

 

I just stopped at level1 (20 minutes).

Which was clean in place. By spraying down the passage in the right opening.

I decided to postpone the full cleaning of throttle body till the day I have to take it off ...[replace spark plugs ~160k or so].

Salim

 

What kind of grade/octane gas do you use?

I had read somewhere in the past that using regular or plus contributes to this build up problem. Should always go with Premium.

 

Bad info. I am on my second RX with 127,00 on it and never use anything but 87 octane. I just did the plugs at 125K and they looked like new. Also never had any valid check engine lights or any other problems for that matter. If you do a search and read some of the reg vs preimum discussions you will also find some posts claiming preimum contributes to carbon build up in the RX engine.

 

What are you doing different then that is keeping everything so clean while reducing the carbon build up?

 

Just doing the owners manual recommended maintenance.

 

But so do I and many others who've had the IACV issue. Obviously something is different.

 

Just because some have reported having the IACV issue does not mean everyone is having the problem. I really don't think anything is different here. I am not claiming using 87 octane is preventing any problems, just not causing any. I haven't had the issue yet, but could have it next week or next year.

 

Gas quality has more to do with build up than gas grade. Although most 91 grade has more cleaning agents, good quality 87 grade will be the same. Shell 87 is TopTier certified and works wonders in my BMW and Lexus. Whenever I fill up at ESSO, I find that unless I use premium, both cars give me bad mileage and noticeable drop in performance. I used to have an Infiniti that actually idled rough with any grade of ESSO gas but ran like a charm on Shell 87.

 

My $0.02

Throttle body is upstream of the injectors. But since air flows through the two, vapors do make it to the throttle body.

As I stated, I have not disected the throttle body and merely peeked past the flaps. I did not see any massive build up ... 10yrs + 130k miles ... I would say reasonable clean. Spraying the cleaner, cleared up the browning. My problem was somewhat sticky valve (IACV) which moved freely after the cleaning.

I have used 99.9% mid-grade gas [99.999% from Exxon].

Carbon build up would be in the head. Dirty gas will cause injector problems.

IACV and throttle body build-up is purely age.

Salim