ducati67

Hi,
I own a 2018 IS300 AWD V6. Ive driven stick my entire life and this is my first automatic transmission car. This car shifts gears so early that ill be in 5th gear going about 40 miles an hour and if i slow down it will still remain in 5th gear. It seems like it tries to get into 5th gear as soon as possible. When its in 5th gear it tries it best not to get out of it. This really affects the performance of the car when im driving slower speeds. I know i can use manual shifting to help with this but i feel the timings of the gear shifts are off. Is there any ways to fix this?

Thanks

Jazzrock

Are you driving in Drive or Sport? Sport will shift earlier than Drive.

Sasnuke

Welcome to the forum!

As you have the IS300, I'm assuming you have the 4 cylinder turbo RWD with the 8 Speed Auto.
If you have the AWD, then it's the V6 with the 6 speed Auto.

The shifting is geared towards fuel economy, whether you're in Eco Mode or not.
As you drive the car more it will adapt, within reason, to your driving style as it learns.
You can also try switching to Sport Mode which will also alter the shift patterns...keeping in mind all this comes into effect when the vehicle is at operating temperature.
When it's cold the shifting is geared towards warming the engine/drivetrain up as soon as possible, which means not shifting into the highest gear until temp thresholds are reached..
There is nothing to fix as there is nothing broken, but certainly as you drive more it will get better.

At this point the only thing to do is drive the car.

ducati67

I have AWD and dont use the Sport mode.
I bought this Lexus Pre Certified. Has the car already adapted to the previous owner's driving style? Can it still adapt to my driving?
I can understand it wants to save on gas, but going up a hill going 20-25 mph in 5th gear would probably use more gas??

arentz07

I would recommend using Sport mode if you think it is shifting too early. Sport versus Normal is a fairly subtle difference, but it should be more willing to downshift when you are climbing hills, etc.

I'm not sure any adaptation would have taken place, but you could try disconnecting the battery for 30 minutes. I would only do this as a last resort. Unfortunately, I think what you are describing is just how this gearbox is programmed.

jgscott

iTrader: (1)

I thought the Trans ECU along with the ECU Map did learn? But IDK for sure. Worth a Try, but if you do, then as soon as you start up get in and hold it to the floor a few shifts a few times. I know the TPS will because you can def feel a difference on reset.

NickCaesar

I have a 350 with same transmission. You need to drive in sport or it feels heavy and slow..it is!
First thing I do is disable traction control and put it into sport every time I drive.
Throttle response in eco and normal is brutal, sport wakes it up. You also need to learn how the transmission behaves...in normal with low throttle input it is very slow and lethargic...in sport with slightly more aggressive throttle input it’s actually really good. With really aggressive throttle in sport modes it’s awesome....it holds gears like crazy, downshifts aggressively, rev matches and is very responsive.
They are heavy cars with not that much power and because we’re naturally aspirated V6 engine you have to rev them. They don’t make max torque until 4800 rpm...of course going up hill in 5th is going to feel lazy it’s a 3700+ pound Lexus.
Use sport mode, Get a bit more aggressive with throttle input and get the RR Tune if you really want to wake it up.

Sasnuke

It would have adapted to the previous owners driving style.
You have two options:
1. Keep driving and it will learn your driving style eventually
2. Take it to the dealer and ask them to reset the learned values...this may incur a cost, but will speed up the adaption process as it's starting from a blank canvas now

I don't think disconnecting the battery will reset the learned values, not 100% sure though.
It will reset the throttle body learned position, which could lead to a rough idle if the throttle body is currently dirty (like very dirty).

arentz07

Oof. OK. Disconnecting the battery to "reset" the trans was something I've seen repeatedly stated on the forums, but it could've been a rumor.

swaangin

The car does shift weird and I'm noticing it more and more as time goes on. OP is right, car always tries to downshift to 5 (let go of gas going down a hill). Even for Eco mode it's not good because it uses significantly more gas milage.

I feel like sport mode is so twitchy and launches the car forward.. so highway driving it's good, but local roads and stores.. eco is more than enough