I purchased my first Lexus in October, a very clean 2009 ls460. In colder weather (for Tucson AZ) in the 30's to 40's I notice that the transmission slips while the car is accelerating between 2nd and third gear.

By slipping, I mean as the car shifts between 2nd and 3rd it feels like it goes into neutral for a half second, so rpms spike 500 rpm, the car stops accellerating, and then catches as the next gear is finally engaged.

It does this pretty much every day when the car has been sitting overnight on the first steady acceleration after backing out of the garage. It only does it once, subsequent shifts a re pretty much normal.

Every once in a while coming out of a parking lot after say grocery shopping, it will do it again, just once.

I dropped it at the dealer and they of course could not replicate it.

I made a youtube video which shows it sort of. besides the rise in engine rpm, you feel a lurch in the acceleration as it drops down into gear.

Service records showed the trans was serviced just before I bought it.

Just looking for any input, thanks!

 

Aha! We own 2 LS460s (2011 & 2012) and they both do this on the first cold accel. In transmission lingo, it is known as a "2-3 flare". I think it's a characteristic of the Aisin AA80E transmission, and I bet if others tried this they would find that most of them exhibit this same behavior. I live on a 50MPH road, so the first run through the 2-3 shift happens on the way to 50MPH. In a 25-30MPH subdivision the first 2-3 shift might happen as the driver is lifting off the throttle, so it wouldn't be noticeable. Anybody else want to try to see if their car does this? It literally only happens once, on the first accel after a cold start.

 

Happens to me as well. Only first one, same exact thing

 

On cold mornings I'm in agreement with this anomaly.
For me though, its not even when I'm trying to accelerate to that much of an increased speed.
I back out of my garage and drive up the street and am greeted by a stop sign within a few hundred feet, so I may reach about 10mph.
Between me braking and coming to a complete stop, then depressing the gas pedal to accelerate, there is a bit of a stall, but that's usually all I get, and that's not every time.
I find that if I let the car run for a good few minutes, it doesn't occur.

 

My 2012 does the exact 'pause'/flare between 2nd and 3rd when cold. I even had the dealer check the level of tranny fluid (at the required temp) to verify the proper level. He found the level was fine and needed no top off. I'm having my 60k service performed soon and will have the tranny flushed and refilled with Toyota WS-I think it's about 10 quarts. I know it is not required but I keep my vehicles for 10-12 years and put alot of miles on them. Just old school-always changed the tranny fluid on my previous LS's every 30k. I'll also send in a sample to Blackstone Labs to see how it was holding up.

 

My trans does that when cold also. Many cars when cold will do weird things with 2-3 shifts so I never thought too much about it. My Audi for example holds 2nd gear until 3-4k rpm before it shifts to 3rd when cold. After that all shifts become smooth.

 

I always wondered why car manufacturers keep raising the gear count. I'm sure it offers more improvements in fuel economy and performance, but at what price? How many gears will we go? Ten, twelve?

I almost wonder if it's done purely from a bragging perspective at this point, so they can say "8 speed" or "9 speed" on their brochures or TV commercials more so than any real gains versus potential drawbacks. Drawbacks in complexity, mechanical wear from way more gear changes and overall smoothness due to those additional gear changes.

Kind of miss simple, old "five-speed" automatics, heck, four speeds!

I know Acura has a ZF 9 speed in their newer models and they are having problems. Mercedes and their 8 speeds are also bad.

 

Four speeds?! I guess I'm older than you, I remember when the standard was 3 speeds. In fact the first car I remember that my father had was a 1951 Chrysler. It had a semi-automatic transmission. The car had a clutch and you used that to shift into 1st gear, and then the transmission shifted itself the other 2 gears.

 

Nice! The lowest-geared auto I can remember driving in was my dad's old Ford with a three speed I think. I only remember three speeds from the amount of time it shifted as they were huge lurches each time it shifted and I use to count them on trips lol. But, once it hit top gear, that thing sailed for days on a huge speed band.

Yeah, it's crazy how things have changed. It's almost like they're changing it simply because they can verses whether it actually improves anything other than potential headaches. I've always been of the school where simple is better.

 

Mine exhibits this as well. It only does it once (the first set of shifts) and only after it's been sitting overnight.

 

I'd wager the reason the transmission feels this way is because, due to emissions controls, engines need to hold higher revs when cold so as to 'warm things up'. And getting things warm enough for lower emissions doesn't take all that long, thankfully.

I know my wife's '02 RX300's holding of 2nd gear bugs the crap out of me in the winter, but every car I've had post about year model 1998 does the same thing.

This will be my first winter with the LS, so if I'm back here, ranting about it, just point me back to this post and I'll quiet down...probably.

 

This characteristic exists even if the engine has fully warmed up before driving away.

 

How long do you let it sit and idle before the temperature gauge reads about 1/3 of its travel?

Both of you said it happens after the car has been sitting overnight, so it's a cold-start thing.

 

It happens regardless of whether the car idles for 20 minutes or not at all. BUT it only happens after sitting for longer than 8-12 hours with the engine off. This is why I think it's a characteristic of the transmission itself and not the engine temperature. So in other words, perhaps transmission temperature until those valves open up.

 

to avoid the shift delays and to prolong your tranny,just warm the car up for at least five minutes in the morning.