xxx350L

I drive my 2019 RX 350L with 8 spd trans in sport mode 100% of the time; no hesitation. No problem. No worries.

dibl

Hmmmm. Possibly they tweaked the 8 spd. transmission design, and/or the software that controls it, for 2019, as a result of hearing customer complaints about it. Given their warranty liability, they apparently don't consider the issue to be a reliability threat, or they would do a recall to correct it.

DMPesso

I own a 2017 F sport, have gotten loaners that are 2018 and 2019 and honestly the 2019 RXL had a very laggy transmission so it appears that they did not fix it. The 2019 felt sort of like my 2017 did before the TSB update. The pedal felt much heavier too, not as responsive as my 2017. Not sure if the throttle mapping is different in f sports versus regular. Seems like it would be as the TSB has a different update number for F sports. Also, the 2019 is not a new transmission so what did the dealer mean when they told you that? I hated the mapping on the 2019. The 2018 drove nice though, go figure. Could have been the 18” wheels since the RX was designed with them. Just keep it in sport mode and it drives amazing, the transmission gets confused in normal mode too often. I never have problems in sport mode. You feel the gear hunting when your in the lower gears in normal mode, shifts up and down too much. Sport mode I don’t feel anything as it’s always staying in the lower gear ready for you to press the gas with instant response.

Your 2018 F sport has hesitation even in sport mode?

also - DONT mix the gas, use ONLY 93 from a quality gas station like shell. You will notice the difference. The car in normal mode always tries to learn the shifting habits and save gas by keeping the car in low RPM. First few tanks of 93 the car felt like a rocket, then once it adjusted to the octane it went back to normal low rpm sluggish response. However it is still much better then with regular gas. Sport mode must eliminate that transmission learning your shifting because I don’t have issues in sport mode. If the car didn’t have sport mode I wouldn’t be able to live with it. In city traffic the hesitation is the most annoying.

Cocal

Mine 2017 has occasionally a slight hesitation in normal mode none whatsoever in sports mode so whenever I'm in the city and need instant response that's how I drive it.

DMPesso

Yup same here. Highway is fine but city driving I always use sport mode.

xxx350L

I’ve got a 2019 RX350L with 8 speed, and it’s definitely not “laggy” as you put it. I came from a 2018 BMW X3 M40i with a ZF 8 spd, and though we’re talking apples and oranges, I was use to very quick positive shifts in the Bimmer. The RX in sport mode is, IMO, equivalent to the Bimmer “comfort” mode, but not laggy. If there’s any laggy, it’s in the power band and no torque. Drivability is fine for a comfort cruiser. And on the gas issue, use Tier 1. Period.

dibl

Thanks DMPesso -- I am going to try straight 91 octane from Shell for awhile. I always put it in sport mode. I actually love the car -- such a pleasure to drive, especially on rural roads with hills and valleys. The "hesitation" is only noticeable on gentle/normal accelerations in the 15-40 mph range. Harder accelerations proceed as expected. I never notice it during freeway driving. BTW, my 2018 gets better gas mileage than my 2015 ever did -- I have seen over 25 mpg on day trips that were mostly on state and county roads. My interpretation of the service manager's comment was "I hear that a lot from the customers with the newer 8 spd. transmission -- it is a known phenomenon that I can't do anything about."

DMPesso

i meant laggy in normal mode only. The gas pedal just felt harder to push then the 2017 f sport. But yea in sport mode it’s great. If you enjoy it coming from a BMW then that’s amazing.


Forget 91, use 93. The higher the better. I love the car also, thank god it has sport mode. Most definitely in the lower gears and under 40mph like you say I notice the hesitation but not in sport mode. Anytime there’s traffic or it’s not rural driving I use sport mode and it solves any hesitation. The f sport is really fun to drive in sport +. Love the car also besides the hesitation. Sport mode makes up for it

907rx

The fuel industry really did everyone a disservice by calling higher octane fuel “premium”. The octane rating has nothing to do with the quality of fuel and more to do with how easily it is to ignited. The higher the octane, the harder it is to ignite. Higher compression motors need higher octane to prevent pre-detonation (the fuel can ignite from being compressed rather than from a spark plug when the motor intends for that cylinder to fire). If people are noticing a difference it’s either placebo or bad engineering on Toyota/Lexus. Looks like the compression ratio on the 3.5l is around 11.8:1 that does seem pretty high for 87 octane. It may be pulling a bunch of timing to compensate? I have only had a week with my new to me 2017 RX 350 so I will try pay close attention to how she drives on 87 which is what I’ve been using.

Cocal

I've always used 91 as for my driving it's OK, but if I wanted better response I'd definitely go up to 93. The whole engine feels better when the CPU doesn't have to retard ignition at least that's how it feels to me.

Cocal

Exactly! Lexus upon inquiry by a member here did say that they used 91 on all their tests, but you can't make the blind see.
There are those that even say that Lexus "recommends" 87 just because the manual it says that one can go as low 87 (after which the CPU cannot compensate) and instead of heeding the warning they see it as a must, no such warning for higher octane. I suppose to each his own and also it depends whether one owns or leases.

ravenuer

So, did you get a new transmission? If so, did it fix the problem?

stevemcb

My dealer called me today and said the Transmission issue of gear searching should be resolved in the next week or so. (Maybe!). Will keep you informed.

stevemcb

My dealer called me today and said the Transmission issue of gear searching and jerking may or should be resolved in the next week or so. (Maybe!). Will keep you informed. Check with your dealer.

dibl

Fingers crossed!

@ravenuer, no, he was referring to the newer 8 speed transmission, not that I was going to get a new one.

I'm going to try a tank or two of 93 octane Shell gas, but if the "hesitation" is truly due to transmission programming, I do not expect that the grade of gasoline is going to have any effect on it.