Pittsy

Sometimes after doing hard braking then immediately getting on the gas again at slower speeds the converter has to catch up. It feels like it's not even accelerating yet its revving, but after a second or two it catches up and starts accelerating normally again.

Fizzboy7

Yes, definitely get that from time to time with all my cars. What's happening here though is no revving at all. Just depressing the gas pedal and no reaction.

Pittsy

I hate to ask, but are you two foot driving? Serious question, the cars have a feature that closes the TB if brake and gas are applied.

Fizzboy7

No, never have and never will.

Pittsy

It honestly sounds like your throttle body isn't even opening. Can you see if there are any stored codes? Even if your MIL isn't on, you can still have some stored codes.

Solara350

Transmission hickups jerky happened on all of my newer Lexus ! check the ES350 forum it happens on all newer ES350.
"It's your Transmission fluid level is low or not leveled"
1. People say a computer needs to learn your driving style/habit... it doesn't make sense, it's mechanical, not psychological.
2. People say it's a shifting solenoid, this is electrical and if this happens it usually sends a CHECK engine or puts your car in limp mode.
3. People say it is bad gas ! what gas has to do with transmission shifting?
People say anything and could be anything.

Lexus Factory do underfill trans fluid these days, Toyota Lexus now hired morons for cheap labor it's not the 90s anymore, in my case I go change and fill trans fluid and put 150ml more than the fluid I drained out. my 3rd gen IS350/RC350 gear jerks at 4th, my IS250 2nd/3rd and NX200t gear jerks at 3rd, downshift seems to happens more than upshift.
I recently changed fluid on my RC350, 3.6liters drained out I put back in 3.8liters, and my NX200t, drained out 1.5liters i put back in 1.7liters, they smooth out after that, my RC350 shifts so nice in Sport+ manual and auto.

In your case by the way you've described is...gears delaying or searching for gears, the best way is to bring to the dealership and check for trans fluid level, low fluid or old fluid will delay gear shifting/jerking etc.
The worse scenario is your shifting solenoid but i don't think so...not Toyota Lexus your car is brand new...... but here some hints you might wanna look at.
7 signs of solenoid failure
Delayed or unpredictable gear shifting. ...
Skipping gears. ...
Getting stuck in certain gears. ...
Vehicle sluggishness. ...
Inability to downshift/upshift. ...
Check Engine light / transmission warning light. ...
Engine continues to rev when applying the brakes.
Good luck and enjoy your new Lexus IS350 sir.

Fizzboy7

Thank you for the very informative break-down of possibilities. I've read it all and will consider all. At this point, it's pretty clear I need to take it to the dealer and have the fluid level checked. I think that is number one. I will keep everyone posted on what they find.

Pittsy

It'll be pretty hard for them to replicate it. Ive only experienced it once or twice in the RC. Is it happening all the time for you?

Fizzboy7

It's plausible... does sound like something is not working right, such as that. (There's just no response or revving when I depress the gas.) No lights have come on. But maybe the dealer can pull up some codes. I need to make an appointment very soon. Thank you for your comments, very helpful.

Fizzboy7

It's only happened three times. I tried replicating it yesterday. Did all the patterns that caused it the last time, but it didn't surface. I agree, the dealer is not going to be able to make it happen. My only hope is maybe an internal code will pop up or the fluid level is low.

Takenbacon

I'll be interested in seeing what this turns out to be, I've experienced very similar with my 2020 IS350 as well, fairly inconsistent and only happens from a stop/very low speed situations when I need to give it a moderate+ amount of throttle, like it just hesitates for several seconds before any acceleration. Actually rather dangerous honestly too in certain situations. I previously had a 2019 IS300 and never had this issue, and both cars have the exact same engine/transmission combo.

Fizzboy7

When it's happened, did the engine rev and the rpm's at least go up? When it happens to mine, there is none of that. Just no response from the engine at all.

Takenbacon

No increase in RPM, basically just no response from the throttle.

cerbois

any updates or resolutions ???
My is350 had a weird shift this morning when I first started driving . Car was COLD. 3500 Miles and I m not sure what I even felt. thought it slipped at about 25 MPH coming thru a turn but only happened once and I was caught off guard cause it always shifted great.
I was hardly on the gas and the road were dry.
When I looked down I thought I saw 5th gear. regular mode.

arentz07

If it was rev flare when cold, that is normal. The car does that in order to smooth out the shifts when it is cold.