Rx400h "lurches"

[louis'ride]

Geez...how widespread is this "lurching" problem?

I'm about to give up on Toyota altogether. They can't seem to make a drivetrain/transmission that doesn't have some sort of "driveability" problem at the very least. The new ES/Camry has enough instances of the "shifting flare" that it's effectively off my list. The 330 5-speed in the Avalon/Sienna/Highlander/RX has plenty of owner complaints.

It's amazing to me that the RX is extolled for its ride quality in virtually every magazine review even though it has a relatively short wheelbase. But, combine that with a "lurching" transmission and ride goes out the window. You'd think the CVT would smooth out the power input to the drive wheels.

I test drove an RX400h on back roads and didn't particularly notice anything, but it's probably the kind of thing that drives you NUTS on a highway.

My wife gets carsick very easily if the circumstances are "right." This sounds like something I shouldn't take a chance on. Need some more opinions.

as noted here and elsewhere, the problem is correctable. it is also not the norm and not part of the design. but make no mistake about it, it is an issue, rather than only a slight annoyance as some have suggested. if you drove a car and didn't feel anything, the car wasn't suffering from the issue.

as i have reported, i thought the lurch issue was resolving, but i have noticed a resumption of the problem during our damp and humid weather the past 2 weeks. i would almost describe the ride at a consistent low speed (25-45) as "rough". my passenger husband used the word "bucking" so it is not just my hyper sensitivity. and here i thought things were getting better. i am going away for a couple of weeks but will be taking the car in right after. why would the wet weather have an effect? by the way it can do this regardless of which propulsion system is working.

[neelratna]

check this thread (on a different forum from this) for more info. you're definitely not alone.

We just brought home a 2006 rx400h with 17k miles. Its only a couple times that I have taken it out on a clean stretch of highway without traffic.

I definitely found the miniature lurches going on trying to maintain 60mph. If this was a regular car it would be clean and smooth. Instead I quickly noticed the micro lurches and transmission variations. I am an ex-pilot and maintain a high situational awareness. I quickly realized that this was not an ordinary phenomenon.

This forum quickly confirmed that I was not alone.

I have a dealer appointment for a TSIB from Lexus as follows:

EG020-06 Visit/Download Link

"ROCKING" FEELING AROUND 40 MPH

Under certain circumstances, 2006 model year RX 400h owners may experience a back and forth “rocking” feeling while attempting to maintain the vehicle at a constant speed around 40 mph. The Hybrid Vehicle (HV) ECU logic has been updated to help improve this condition.

However this says it is a fix for "around 40mph". Will wait and see if this fixes it for the situation at 60mph. Will post results next week.

[skyfish400h]

check this thread (on a different forum from this) for more info. you're definitely not alone.

We just brought home a 2006 rx400h with 17k miles. Its only a couple times that I have taken it out on a clean stretch of highway without traffic.

I definitely found the miniature lurches going on trying to maintain 60mph. If this was a regular car it would be clean and smooth. Instead I quickly noticed the micro lurches and transmission variations. I am an ex-pilot and maintain a high situational awareness. I quickly realized that this was not an ordinary phenomenon.

This forum quickly confirmed that I was not alone.

I have a dealer appointment for a TSIB from Lexus as follows:

EG020-06 Visit/Download Link

"ROCKING" FEELING AROUND 40 MPH

Under certain circumstances, 2006 model year RX 400h owners may experience a back and forth “rocking” feeling while attempting to maintain the vehicle at a constant speed around 40 mph. The Hybrid Vehicle (HV) ECU logic has been updated to help improve this condition.

However this says it is a fix for "around 40mph". Will wait and see if this fixes it for the situation at 60mph. Will post results next week.

You are on the right track. But you need to claim the problem at the higher speed. There is a new TSIB out that address the higher speed. It is another iteration on the control refinement that was put into the first TSIB on the "surge".

I just had my 400h patched and I've noticed a slight increase in MPG performance inspite of lowering the tire pressure form 44psi to 38psi. I also noticed some defaults on the GPS changed and the sunroof needed to be re-initialized, but that could be because they also had to take the dash off to work the defroster TSIB...

Insist on the latest TSIB for the 70 mph (TSIB EG013-07). "EG7022 ROCKING FEELING @ HHGWY SPDS APROX 70MPH", is what it says on my workorder.

[RX400h]

Geez...how widespread is this "lurching" problem?

...

This sounds like something I shouldn't take a chance on. Need some more opinions.

The CVT is amazing. Once you have one you will never want to deal with shifting or an automatic's braindead seeking for the right gear again. It simpley puts the power to the wheels when you need it. Done.

As for the slight surging sensation some have reported, it pales in comparsion to anything you would experinece in a manual or automatic transmission vehicle.

What seems to be happening is the sharing of power delivery between the engine and the electric motor can be mismatched at times which seems to the passenger like you are not holding your foot steady on the gas peddle. "Lurch" is probalby too strong a word for it. Its a control algorithm thing and that is why the code has been updated.

I experienced it for a short time when I had about 1000 mi on the car but have not noticed it since then. Normally crusing is very smooth and surge free even when the electirc motor assist is comming in and out.

In my opion this is not an issue and the HSD drivetrain is world class.

I agree. I have not heard of this issue from any of the RX400h owners I have met or work with and have to believe that it is not present in anywhere near a majority of RX400h owners. Yes, it is noticable in some vehicles, but no, it is not an epidemic by any stretch of the imagination. This transmission is superior to any other I have driven.

Dave