winsalem

anybody else notice roughness/jumpiness in the transmission when slowing to a stop, or crawling along (like in a shopping center)? it's quite evident on my car, and perhaps i just have a problem that nobody else feels.

it's as if the tranny is downshifting when slowing to a stop, and i can really feel it...makes it difficult to come to a smooth stop. and then if i'm moving very very slowly in heavy traffic, it seems to be "wandering" between 1st & 2nd...something like that...and it's very jumpy. not smooth at all.

i realize that Lexus may come up with some reprogramming for trannies (that happened on my '01 GS, and it made a big difference).

06GS300

winsalem, I have noticed this same 'jumpy' feeling from the tranny at low speeds. It doesn't do it al the time though, and seems to do it less than when I first got it.

bigzip

winsalem, mine is doing exactly the way you described. I couldn't have explained it any better.

Ice350

iTrader: (1)

I noticed the quirkiness of the tranny on my two test drives. Both times I got the same answer from the salesman. The transmission tries to think for the driver...making adjustments all the time. Adjustments to the driver's driving style, the road conditions, etc. It's one of the reasons I didn't like the car. It tries to do too much of the driving for you. One of the pleasures of driving is being in control and making the decisions. Plus, too much technology means more that can malfunction.

XeroK00L

Lexus/Toyota's transmissions for V6 = .

Sad to hear that this V6 transmission fiasco happens not only to the 4-year-old ES/RX/Camry but also to the latest 6-speed autos for the new V6. Sigh, I just hate this whole "drive-by-wire" thing.

Sandman

Winsalem, the GS300 transmission automatically downshifts as you slow to a stop. I too found this a bit disconcerting at first but now I'm used to it and actually I find some benefits to it. While driving at about 85mph on the highway I found myself in a panic stop situation and the transmission downshifted all the way to 0mph even though all I did was mash the brake pedal. The engine added braking force and helped me stop quicker. It is a bit disconcerting because this braking force is not uniform. It is the exact same effect you would get with a manual if you were to downshift while braking. When the trans downshifts from say 6th to 5th at first there is no engine braking because the torque converter is not locked - similar to pushing in the clutch. Then 5th gear is selected and the automatic clutch engages. As this happens the engine RPMs rise giving a "jerky" braking action from the engine. Then the trans disengages the clutch as it shifts to 4th and again you feel less braking action followed by a sudden braking action from the engine as the RPMs climb after the clutch engages. This happens all the way down to 1st gear. The harder you brake the more you notice this effect. Also, since the Trans uses fuzzy logic it also gets in a more aggressive shift mode as you drive more aggressively. So if you have been driving hard and then brake hard you will notice it more. If you are cruising along very peacefully you will hardly notice this downshifting - but it is happening if you look at the tach. I think that this process also adds to the responsiveness of the car. Most transmissions disengage the clutch and let you sort of "coast" to a stop with the trans mostly disengaged. If you needed quick power you need to wait for the trans to find the right gear and then engage the clutch. With the GS300 you are always in the correct gear ready to go. So if what you are describing is the same thing I'm describing then my opinion is that it is a good thing - but takes some getting used to. Try out what I have suggested: driving hard and then doing a panic stop to see if the trans behaves like I have described. I'd like to know if you still think it is annoying or actually a feature that adds to performance by mimicing a manual trans.

Best Regards.

winsalem

Sandman,

thx for the great and thoughtful explanation...makes good sense to employ engine braking in this way, and i can see how it might be beneficial in a panic situation.

in the end, however, the main problem for me is in the "creeping" mode, where i'm doing like 5 mph, crawling along in bumper-to-bumper traffic, and the transmission is up- and down-shifting in such short range. it's jerky, as if it's fumbling around for the proper gear, at least on my car...and it's getting annoying. if i'm doing 5 mpg it upshifts (to 2nd, i guess), but if i go ten feet and then slow back down it jerks as it downshifts to 1st. i'm just hoping Lexus can make a programming change at some point to smooth-out this low-speed shifting.

by the way, i just read a review of a new mercedes in C&D, and they noted the same downshifting taking place as the car slowed, making a smooth stop tough to do. so it ain't just Lexus.

osx-addict

You could always (in those situations) move the shift lever to "M" (or is it "s"?) to put it into manual mode and override what it wants to do.. I've done that quite a few times where you're in very slow traffic.. Works fine for me..

bigzip

That's a very good idea, never thought of it. Thanks

lexuslover

i used to do that too on the RX, but no M mode, just different gears. not the best thing to do, but i couldn't stand the herky jerky transmission after a while.

winsalem, i experienced the exact same thing you described in your post, except on the RX. i had it checked out on numerous occasions at the dealer. the most recent thing that finally fixed the gear hunting was replacing the transmission cooler lines. before that, they did other stuff, like reset the ecu, but it wasn't much use. i don't know if the new GS300 will develop the same pattern as the RX since they are totally different transmissions, but something to think about if it doesn't go away or "learn your driving habits" as the dealer would say . . .

Sandman

Winsalem,

The problem you describe around 5mph is not something that I have experienced with my 06GS300. I'll have to be on the look-out for it. Since others have experienced a similar thing maybe it isn't an isolated thing. But maybe it is a problem that can be fixed. Several have written that they hear a loud tapping from the fuel pump but I have never heard this in my car - even under hard acceleration. On our 04 RX330 there is a strange "thunk" that happens when coasting and I decelerate through 30mph. The dealer claims that there is some backlash in the drive shafts. I have been in other RX330s that have the same problem and then I have been in others that don't do it at all no matter how hard I try to reproduce it. So as good as Lexus is there does seem to be a variability with some of these issues.

I sure hope that they can fix this for you. If my car had a gear-hunt problem it would probably drive me crazy. I'm curious to hear how this develops for you so please keep us posted. Good Luck!

winsalem

...took car to dealer for replacement of an interior part that was scratched before i bought the GS...gratis, of course...

asked the service rep if others had reported any of the "jumpy" transmission problem i am experiencing. answer was no.

didn't have time for technician to drive with me, but i've reported the prob and will soon take it in for them to test. ODO is at 1,800 miles by the way.

i actually had a passenger ask me what the hell was going on the other day. we were at a stoplight behind ten cars, crawling forward slowly as each one turned right on red. with each tiny tiny application of the accelerator, the transmission would upshift, and then downshift -- and lurch. i find myself subconsciously applying my right foot like i'm walking in a mine field, just trying to accomplish a smooth ride. it's not quite a neck-snapping event, but it sure ain't what i want in a $52k automobile, and totally different from all my Lexi.

hoping there will be a TSB for me at some point, i may just need a re-program or something. oh well. still love the car, but hate the jumpy tranny.

TheRupp

I think it might have something to do with the fact that around 25 mph, it's in 2nd gear, and to preserve gas, it goes 2nd --> 6th. I noticed this a little on the 430 as well, but it's pretty quick to downshift back to 2nd when needed, which is what I think the "bump" feeling is (the shift from 6th --> 2nd)

Ice350

iTrader: (1)

That sounds like what my es300 was doing. It turned out to be the device that controls the idle...which is much less serious than a tranny problem. I hope yours isn't the worse.

Dwiz50

[QUOTE=winsalem;1343141]anybody else notice roughness/jumpiness in the transmission when slowing to a stop, or crawling along (like in a shopping center)? it's quite evident on my car, and perhaps i just have a problem that nobody else feels.

it's as if the tranny is downshifting when slowing to a stop, and i can really feel it...makes it difficult to come to a smooth stop. and then if i'm moving very very slowly in heavy traffic, it seems to be "wandering" between 1st & 2nd...something like that...and it's very jumpy. not smooth at all.

i realize that Lexus may come up with some reprogramming for trannies (that happened on my '01 GS, and it made a big difference).[/QUOTE.

I know this is 10 years later ,but I also have a 2006 Lexus Gs300 with the exact same problem. Did you ever figure out what the cause was ?