toyotaman7

If you have a F sport then though can customize ur so that the transmission would be in sorry and leave the suspension in eco or normal.

RXLexusF

Could you give us more detail about the fix? Thanks!

P17rx350

Wanted to give the group an update, my wife put 93 Octane in the car and noticed an immediate difference. She's been driving for the last week and the car is night and day different. Significantly smoother with the higher octane and the cars drives much better, take off is smoother and more aggressive. I didn't believe her so I drove the car and I'm a believer, still some very slight hesitation as I tried to create the hesitation scenario but I can say I like driving the car now. So that leads me to ask the question, is the problems trans related or is the engine tuned to run on the higher octane but Lexus is marketing their cars can run on 87 to increase sales? All the other Japanese and Luxury brands recommend premium gas for their 6 cylinder engines. I think Lexus still has some work to do on the transmission logic but as others have commented the premium gas definitely helps.

Baxter64

Sounds like just a US con to make them more appealable.

In Australia, the Toyota/Lexus recommended fuel is Premium... same cars.. same engines.

615tpc

In my understanding they use a timing advance algorithm in combination with knock sensors. The system tries to achieve Optimum torque without knock in the entire rpm range. In high load higher rpms the timing is adjusted to avoid engine damage which means optimum torque won't be the same for lower octane vs higher octane. So with higher octane you may notice a performance gain and possibly fuel saving if you are routinely heavy on throttle. May not be enough to justify the extra cost. Also, the system needs consistency in fuel octane for best performance.

P17rx350

Thanks, I've also asked her to track fuel economy for the next few tanks as well. For her it's not about the performance as she's a slow driver but she's definitely happy about the smoother drive.

computerwi

Coming from an NX, I can say the NX didn't have transmission issues like this main issue described in this thread. The latter issue you describe is a common problem for many transmissions though.

msh3l

Same here,

95 octane is recommended as per car manual.

Mrdirt

I too am a first time Lexus buyer with a RX350 and have noticed the same hesitation in the lower gears. Additionally, I hear what I can only describe as a "low moan" associated with a vibration when starting slowly. It is most pronounced when starting up a low incline. I just had a 5K service where I complained about these issues for the second time and was told that some drivers are complaining about this but that Lexus has not developed a "fix" for this just yet. They will not admit that it is a problem but it is clear that other drivers are experiencing these issues. I have a front wheel drive and am wondering if these problems are experienced by both front wheel and all wheel cars.

Supranut

I have the all-wheel-drive and I have the same vibration and hesitation issues.

clwu

This New review of RX350 states that Premium gas is recommended for performance.

Video at 12:55

s4iscool

sad to report that after enjoying smoother throttle response on premium for 5 tanks, things reverted. Sad how we cant get a straight story from Lexus and its dealers...there is a fix, there isnt a fix, theres no problem, lexus knows and working on a fix, it's coming...

stevemcb

This probably should be merged with the noise and vibration part of the forum as it all seems to tie in together .

LexRexBlue

Not sure if anything was done to update mine, but the hesitation seems to be disappearing ever since I reached the 3000+ miles. I have always used BP regular gas except for one tank of Shell regular.

Darith

I apologize for the delayed response I was searching for the print out from the last visit at the dealership since the fix. I look at the work order (I stressed this acceleration/transition hesitation issue to the rep who was taking care of me and she did notify the mechanics about it), but there was nothing on the physical print out that lists the fix for it as I do believe what another member mentioned before in this thread that it would be a discreet fix once you bring your vehicle into the dealership (which makes me curious if it was an ECU transmission setting to make the MPG numbers look good, but don't quote me on that as I'm just speculating). To update from my last post, the hesitation transmission issue is still gone/fixed and it's still a pleasure to drive (and I'm still putting in regular 87 gas the entire time).

I'm trying to track my MPG to see if it has been affected, but I do mostly 70% city/30% highway and the highest was 24 MPG but average around 17-18 MPG which does seem a bit low...