Finally got my appointment at dealership (after one month wait for a slot) for intermittent hesitation upon accelerating uphills in my 2021 350 ES. Original owner 12,000mi. of easy driving.
Dealt with the service manager personally. We went for long ride but symptoms, as feared, were difficult to replicate.
Told him I changed air filter and didn’t seem to help, though old one was hardly dirty,
Concluded nothing wrong with car. He suggested I try switching fuels from the previous one I exclusively used and maybe do Top Tier Fuel with slightly more octane to see if that would help.
I did. Went to Sunoco, 91 octane. Made a big difference. Now people will say placebo effect, just throwing money out, car made to run on regular, etc. etc. But this difference from Get-Go 87 octane to Sunoco 91 works in my specific, anecdotal situation, my car where I drive it, how I drive it, etc.
So for now problem seems resolved. Will update in a month or so.

 

SHABOOM,
A year and a half ago, I bought a new 2021 ES 350. 8,000 miles on it now. Very pleased. However, as I've mentioned on this forum once or twice, when going up a hill, accelerating moderately between 40-45 mph, I get a minor engine hesitation. Past 45 mph it disappears. Accelerate a bit harder, it disappears. Tried premium gas. No difference. Is this something I should pursue before while under warranty or might it just go away. Any ideas what causes it?


What do you think changed since you posted this?
Just curious.

 

Two questions:

how exactly is top tier gas defined? Is there a list of retailers that count as top tier, or is it more specific to individual stations getting certain supply?

what exactly do you mean by hesitation? Do you mean that Rpm’s did not increase with pedal input at the normal pace, or something more significant?

 

Felt as though the flow of fuel was temporarily partial. RPM’s were slightly erratic, always only for a second or two. Felt like a prior car felt when it called for premium fuel and I mistakenly used regular unleaded.
There is an on-list of gasolines officially designated Top Tier. Sunoco, Citgo are the two we have in our suburb. Using the higher octane version of the Sunoco may have done the trick. Service manager said try it—-nothing to lose. I guess the particulars of every driving scenario are unique and in mine this seemed to help solve my problem, whatever the problem was. But the symptoms sound identical to your situation and I hope you may benefit from my experience. As the service guy said, you have nothing to lose.

 

https://www.toptiergas.com/gasoline-brands/

 

There's a TOP TIER™ web site that has some of the details you're asking about. "Some" because what qualifies for TOP TIER™ is pretty non-informative (from the RETAILER "LEARN MORE" linked web page):
There's also a more detailed Gasoline Performance Standard (pdf) describing the test methods used and the performance requirements that must be meet to be licensed as TOP TIER™.

On the TOP TIER™ Fuel Stations web page there's buttons that will take you search/info pages for brands and stations. I'm not certain at least some of the information is the most up-to-date - there's some branded gasoline stations that I know of that aren't on the map displayed station list.

 

I'm betting that the premium gas is placebo all the way. These cars are calibrated to run perfectly on regular, and that being the case, premium should make no difference whatsoever. Many modern cars are set up to run fine on regular but to sense the presence of premium and advance the timing for better performance. The Mazda turbo 4 is one such engine. I'm pretty sure our V6 is NOT such a setup.

Top Tier is another matter. It's worth noting that the owner's manual does not encourage the use of premium, but it does encourage the use of Top Tier. Premium vs. Regular is not a quality difference, it's a difference in the explosive energy stored in the fuel. Top Tier is a quality standard, basically certifying that the gasoline has more detergent additives in it. Long-term, that prevents clogging of the rather temperamental high-pressure direct fuel injection nozzles. Short-term, you wouldn't notice any difference from that, either.

 

If you look at the "OUR SPONSORS" section of the TOP TIER™ web site you'll see Toyota listed. So, you can't rule out a bit of mutual backscratching going on with that.


That isn't correct. Premium versus Regular gasoline is an octane rating difference - not an energy content difference - and also a quality measure.

Energy content is not part of any of the various official octane rating standards. While one can find a multitude of explanations and definitions of octane rating, they all pretty much distill down to something like the octane rating is a quality measure of a gasoline blend of various types of hydrocarbon molecules (and additional additives) stew's resistance to uncontrolled spontaneous combustion (engine knocking) from temperature and pressure.

While most modern engines have some form of anti-knock control system, whether or not a fuel octane grade will allow or prevent engine knocking in a particular gasoline engine with the potential for engine damage in the long term is one of many other measures of fuel quality.

Above quibble's aside, you're correct with this.

Before the TOP TIER™ fuel rating existed, the first fuel injection car I owned kept having fuel injector problems. Eventually a mechanic told me he knew exactly what brand of gas I was using based upon the deposits he was seeing on the bad fuel injectors. He said avoid that brand of "cheap" gas (and a few others) and the fuel injector problems would cease. He was right - by avoiding the "cheap" gas no more injector issues. (It also takes a whole lot of buying "a few pennies less per gallon" gas to save enough to cover the cost of fixing bad fuel injector problems. With that mid-teens to mid 20s mpg car, the "cheap" gas ended up being overall more expense to use then the "good", more expensive per gallon gas.)

 

Here in Australia, the ES300h (and ES350 when it was offered) is recommended to use 98 Octane fuel (in the manual and sticker inside the fuel door), which translates to 91 octane + top tier in the states, no idea why there is a discrepancy between recommended fuel between countries, but good fuel = happy car.

I have been using said 91 octane top tier fuel, normal driving mode, and my dash is currently showing 49mpg (or 4.8L/100km is how we measure in Australia), which is exactly the claimed max fuel efficiency of the ES300h by Lexus Australia, not bad at all

 

I personally believe you've identified a solution to your up-hill "hesitation". Two reasons why I say this. After 12k miles of easy driving with "regular" gas, you may have some carbon build up on the valves and injectors. When you push it hard (harder than your normal driving) you have hesitation. Premium fuel, with higher octane, will help. Running injector cleaner every few tanks, will also help.

I have a 2007 GS350...2GR-FSE engine that requires premium fuel. Your ES350 has a 2GR-FKS, which is essentially a 2GR-FSE with the simulated on-demand Atkinson cycle. I'm sure the designers made ECU tweaks for the regular gas, etc, but using top tier premium gas can't hurt when your engine is under heavy load. If you seldom put her under load, premium isn't necessary.

Test your theory and report back. You may also want to go back to regular but add a bottle of Chevron injector cleaner and see what happens.

Thanks for sharing your issue.

 

Pretty sure after further reading that you're right and I'm wrong about the properties of premium gasoline. Thanks for the constructive correction.

One point I will disagree on is the notion of a Toyota "backscratching" conflict of interest in both sponsoring and endorsing the Top Tier standard. I can't really think of a reason Toyota would invest in a gasoline standards entity unless its engineers sincerely found that the additional detergent additives were actually beneficial to the cars.

 

And thank You for your thoughtful response.
For whatever reason(s), the car continues to behave well and drive without hesitation. As my doctor says to me, I am going to say to my Lexus, “Just keep on doing what you’re doing.” I will continue with 91 octane TopTier Fuel. I always hesitate to use additives, for fear it will complicate my ability to pursue a future warranty claim. But hopefully, the Top Tier Fuel will deal with the cleaning detail.
Thanks again.

 

I look at it this way, Top Tier gas isn't any more money than non-Top Tier gas 98% of the time, so I'm going to pick TT every time. Premium gas, however, is just throwing your money on the ground.

 

Seems to be the perfect diet for my Lexus, too. Thanks for your good advice.