ChucklesRX

I bought a 2008 RX 350 last year, and it had the same lag/ rough shifting in lower gears as the OP. Well, just got back from a 3 week vacation, and it is now running perfect!!! I am not a mechanic or electrical engineer, but pretty sure that after sitting in the garage for 3 weeks, the trans 'memory' lost power, and reset, just as disconnecting the battery would do. So if you have this problem, I really suggest disconnecting the battery (not sure how long this needs to be - try overnight), and report back if it helped. Good Luck!!! I am finally very happy with my RX

Turbostar

Since you bumped this thread, I thought I would chime in as well. I just recently purchased a 2008 RX 350 and have also noticed the transmission hunting for which gear it should be in at low speed. It is especially noticeable in my parking garage when going up or down (and I'm on the 4th floor.)

However, I don't really think it is a big issue. Like others have said, it seems like a software/sensor issue, and I don't feel any excessive slipping (and I have rebuilt automatic transmissions before.)

It just seems like the RX is trying to find the optimal gear for what you are doing at low speed, and it takes a second to decide. I will be replacing my battery soon and will update if removing the battery changes anything.

Jet1965

Was the Battery dead on Lexus whenever you returned from vacation. Did he continue to shift normal after that day forward?

ReynoldG

RX400h. 2008. 3.3L engine
i felt like the transmission was slipping, a Mech told yea it’s the transmission so I took it to a transmission shop. ATLAS TRANSMISSION in WPB Fl, the tech drove it and scanned and showed me IT’s NOT THE TRANSMISSION. It were bad coils or plugs. His scanner showed 1 & 2 cylinders were misfiring. Since the coils were new my next guess would be the plugs. I changed them and now it’s all good, car runs great again.

ChucklesRX

HI. The battery was not dead. My guess is that not running the car starved the ECU such that it was reset to factory specks. It was good for maybe 6 months. Now I simply pull the ECI #1 fuse and leave it out overnight every 6-12 months as needed to accomplish the same thing. (If I pulled it for shorter time periods it did not seem to work as well). I don't pull the cable from the battery as others have suggested so that I do not need to reset some things like the windows and other settings. Hope this helps!

Felix

Really best to make your own new thread, btw your rx400 has a CVT trans......