Test Drive Of 08 Rx350 - Tranny Question

[Mycopsycho]

This morning I did a test drive of a new '08 RX350. We drove west of Denver up I-70 on the long 6% grade up into the mountains. I noticed that the transmission kept hunting for gears - shifting up, then down, and up again. I tried to keep at the 65 mph speed limit but the tranny kept shifting up and the speed would drop back down to about 55-60. So I would give it more throttle and it would downshift and just as I thought I would be cruising up the mountain at 65 it would shift again and my speed would drop. This was annoying and I had hoped for better performance. Is this typical of this transmission when driving in the mountains at altitude? Or am I just too accustomed to my diesel truck?

Bernie

Denver, CO

[wwest]

This morning I did a test drive of a new '08 RX350. We drove west of Denver up I-70 on the long 6% grade up into the mountains. I noticed that the transmission kept hunting for gears - shifting up, then down, and up again. I tried to keep at the 65 mph speed limit but the tranny kept shifting up and the speed would drop back down to about 55-60. So I would give it more throttle and it would downshift and just as I thought I would be cruising up the mountain at 65 it would shift again and my speed would drop. This was annoying and I had hoped for better performance. Is this typical of this transmission when driving in the mountains at altitude? Or am I just too accustomed to my diesel truck?

Bernie

Denver, CO

The automatic transmissions design and manufacturing folks are current trying their best to match the FE performance of the newly arrived on the market CVT's, Continuously Variable Transmissions.

They can't.

But that doesn't mean they won't try.

The new 6 speed transaxles, uning the OD lockup clutch, can now operate with as many as 9 "gear" ratios.

So the engine/transaxle ECU firmware will be continuously "hunting" for the best gear ratio for FE and sometimes that means the slightest change in roadbed inclination will result in a gear change.

I first encountered this on vacation last spring. The first week we had a new Mazda minivan and it about drove me crazy with its "shiftiness". The ssecond week we have a new Chrysler Sebring (V6, I checked) ...SAME problem, slightest undulation in the roadbed and it would shift. Amazingly enough I found that cruise control seemed to be better at reducing the number of shifts than I.

[GDixon]

This morning I did a test drive of a new '08 RX350. We drove west of Denver up I-70 on the long 6% grade up into the mountains. I noticed that the transmission kept hunting for gears - shifting up, then down, and up again. I tried to keep at the 65 mph speed limit but the tranny kept shifting up and the speed would drop back down to about 55-60. So I would give it more throttle and it would downshift and just as I thought I would be cruising up the mountain at 65 it would shift again and my speed would drop. This was annoying and I had hoped for better performance. Is this typical of this transmission when driving in the mountains at altitude? Or am I just too accustomed to my diesel truck?

Bernie

Denver, CO

Check out this post from the LOC site.

http://us.lexusownersclub.com/forums/index...ic=41598&hl

[GordonB]

This morning I did a test drive of a new '08 RX350. We drove west of Denver up I-70 on the long 6% grade up into the mountains. I noticed that the transmission kept hunting for gears - shifting up, then down, and up again. I tried to keep at the 65 mph speed limit but the tranny kept shifting up and the speed would drop back down to about 55-60. So I would give it more throttle and it would downshift and just as I thought I would be cruising up the mountain at 65 it would shift again and my speed would drop. This was annoying and I had hoped for better performance. Is this typical of this transmission when driving in the mountains at altitude? Or am I just too accustomed to my diesel truck?

Bernie

Denver, CO

Check out this post from the LOC site.

http://us.lexusownersclub.com/forums/index...ic=41598&hl

I just joined this forum in search of information on the very problem that you are describing. My new RX350 bothers me the most in slower traffic situations by downshifting and giving the appearance of a slipping transmission. This car only has 3000 miles on it, and I have already taken it back to the dealership with this complaint. The mechanic did acknowledge the problem on a test drive, and then told me that it was a normal function. He described the transmission as a "Learning Transmission", and said it would get used to my driving characteristics after a while. He also acknowleged that the ES350 has the same transmission, and does the same thing.

If anyone out there reading this forum has had the same problem, or knows of any fixes, please let me know

Thanks,

Gordon Fish

Sandpoint, ID

[wwest]

This morning I did a test drive of a new '08 RX350. We drove west of Denver up I-70 on the long 6% grade up into the mountains. I noticed that the transmission kept hunting for gears - shifting up, then down, and up again. I tried to keep at the 65 mph speed limit but the tranny kept shifting up and the speed would drop back down to about 55-60. So I would give it more throttle and it would downshift and just as I thought I would be cruising up the mountain at 65 it would shift again and my speed would drop. This was annoying and I had hoped for better performance. Is this typical of this transmission when driving in the mountains at altitude? Or am I just too accustomed to my diesel truck?

Bernie

Denver, CO

Check out this post from the LOC site.

http://us.lexusownersclub.com/forums/index...ic=41598&hl

I just joined this forum in search of information on the very problem that you are describing. My new RX350 bothers me the most in slower traffic situations by downshifting and giving the appearance of a slipping transmission. This car only has 3000 miles on it, and I have already taken it back to the dealership with this complaint. The mechanic did acknowledge the problem on a test drive, and then told me that it was a normal function. He described the transmission as a "Learning Transmission", and said it would get used to my driving characteristics after a while. He also acknowleged that the ES350 has the same transmission, and does the same thing.

If anyone out there reading this forum has had the same problem, or knows of any fixes, please let me know

Thanks,

Gordon Fish

Sandpoint, ID

On vacation last year I noticed that a new Mazda minivan and a Chrysler Sebring did the same thing. Apparently these new V6 engines are so POWERFULL that when coupled with the most optimal O/D gear ratios they can pull the car along at a very reasonable crusing speed at an exceptionally low operating RPM.

Basically these engines are often, using multiple O/D ratios, being operated in cruise right on the CUSP of lugging. Almost, but not quite at the point of encountering engine knock/ping.

BUT....

The instant, the VERY instant, any additional engine loading (slight incline..) is encountered the transaxle MUST be downshifted.

Best FE, ABSOLUTE best FE....

But for FWD and F/AWD Toyota and Lexus vehicles this whole scenerio is exacerbated by the transaxle design flaw incorporated as a result of the design of the original RX300 transaxle. Due to the abolition of the transaxles ATF pressure holding/sustaining accumulator back late in the last century these transaxles cannot support two gear changes in quick succession.

[cyberchic26]

I have this same prpblem with my 09 rx350...they told me its working as designed.

Sometimes it seems like its in neatral after I stop at a stop sign and then go immeidately.

I hate this car. I hate lexus. I feel like driving the car thru the dealership window!!!

I have had the car for a year noe and if i knew it drove like this I would NEVER have bought it.

[GDixon]

I have this same prpblem with my 09 rx350...they told me its working as designed.

Sometimes it seems like its in neatral after I stop at a stop sign and then go immeidately.

I hate this car. I hate lexus. I feel like driving the car thru the dealership window!!!

I have had the car for a year noe and if i knew it drove like this I would NEVER have bought it.

You could try disconnecting the battery for a half hour or so to reset the car's "learning" computer. There will be other things shut off as well but the owner's manual will explain how to turn them back on.

It might help and it might not.