sandy14

Interesting, thanks for sharing.

fmast342

This issue where the transmission hesitates/jerks in normal mode at low speeds or coming off of a stop is driving me crazy. Any advice? One thing I've found is that Sport Mode seems to eliminate this issue (which I have seen recommended here) but I wonder if Sport Mode inherently uses more fuel by design or could it possibly use more fuel but only if you drive more aggressively due to the easier ability to accelerate and such? Thanks.

Macs4RX

You are not alone - the transmission jerkiness from a standing stop and at low speeds is also driving me crazy. As a workaround, I've been using the S-mode almost exclusively and this helps smooth things out considerably. I really believe the software mapping of this transmission needs some work and is, in my opinion, the weak link in an otherwise fantastic SUV.

s4iscool

+1 here, only 300 miles on the F sport and ive felt the jerk at slow parking lot speeds when slowing down to almost a stop.

bootman

Your right foot controls your gas mileage.

This is all due to the transmission starting off in a higher gear and we have to become used to it.
We think it isn't going fast enough then plant our foot which causes a downshift that feels jerky.
Welcome to 8 speed autos.

Once you realize what is going on your right foot can adjust to this and the car becomes smoother over time as you get trained.

I have done it.

Or just keep it in sport which then starts at a lower gear as we have previously become adjusted to with 6speed or less autos.

dfc350

Here's a video I found that explains octane ratings, no-name gas, and Top Tier gas. Basically the current government standards for fuel additives are based on 1995 engines and are obsolete for modern engines.

brhfriend

I always use Sport mode, and recommend it heartedly to all.


The Car Dealer that I bought from said that he did the same thing. He stated that typically Sport Mode only costs 1 MPG in fuel economy. However, I certainly do agree that driving style could further impact this. FYI, I have not independently verified the impact to MPG.

Tmey5

I am new to this forum but began viewing when I discovered that the Lexus RX uses the same 3.5L V6 as what is used in my 2016 Tacoma. I have been experiencing the same hesitation feel in my Tacoma as what's descibed here. It will stutter when in higher gears, low rpm, and either slightly accelerating or on a slight incline while attempting to maintain speed. If my pickup downshifts, no problem. If it doesn't it will stutter. Feels like a bump.... bump bump, and usually is 2 -3 jerky stutter sensations. Ive been doing alot of research and attemps to find a solution and here is what I find. I too notice a significant difference in value fuel vs top tier fuel. I have found that it does it less often with Chevron, and seemingly less often with the 92. I firmly believe that this 3.5 engine struggles when put into the low rpm and high torque conditions. For the Tacoma, those conditions occur in 4th, 5th and 6rh gear around 1200rpm. What seems to make this stutter happen is when the vehicle is in the higher gears, the lock up converter engages, creating no slip and that the 3.5 struggles in this low rpms, increasing torque situation. This is why people are driving different, in sport mode or in non eco mode, etc. For the Tacoma, we can engage the ECT PWR mode and higher shift points occur, making this situation occur less often. I am sure hoping for a resolution other that just having to drive more aggressively, and I would love to hear from someone with some thoughts on this matter. Until then, if you guys have this same stutter, I encourage the use of better fuel, because it DEFINITELY changes it from ALL the time to only every once in a while.

Macs4RX

At first I was using a store-brand Regular gas. After I saw dfc350's post about Top-Tier gasoline I read about it at the web site and decided to try it. I'm now on my 3rd tank of Shell V-Power Nitro+ 93 octane Premium (Shell is a certified Top-Tier gas retailer - both their Regular and Premium would qualify as Top-Tier, of course). I cannot say unequivocally that it has improved the hesitation and lagging issues because of the inherent placebo effect. However, it certainly hasn't hurt and I believe the car runs a bit smoother. The transmission issues I'm experiencing with my RX350 are mostly felt when mildly accelerating from a stop and through to 3rd gear (if using Drive and Normal mode). This is when I'll typically feel hesitation and lagging/droning. To get around this, I'm using the S-mode manual shifting option, normally starting off the line in S3, upshifting to S4 and finally to S5 while driving around town. It is quite smooth using this approach. As always, just my opinion and ymmv.

NateJG

[QUOTE=dfc350;9528869]Here's a video I found that explains octane ratings, no-name gas, and Top Tier gas. Basically the current government standards for fuel additives are based on 1995 engines and are obsolete for modern engines.


See: http://www.toptiergas.com/deposit-control/

clwu

This is from Lexus website.
"Ratings achieved using the required premium unleaded gasoline with an octane rating of 91 or higher. If premium fuel is not used, performance will decrease."

Apparently, even though Lexus promote 87 Octane as an incentive to buy the RX 350, they actually recommend higher octane for better performance.
People that switched to premium and felt better performance, it's not a placebo effect.

Go here for the source:
http://www.lexus.com/models/RX/speci...350-awd#engine

Scroll down until you see "7.9 SEC"

Click on "0-60 MPH"

Macs4RX

That's an interesting discovery. I'm speculating but my guess is that the "required premium unleaded gasoline with an octane rating of 91 or higher" statement is an error in the pop-up window. If one clicks the RX350 FWD or the RX350 AWD F-Sport, there is no mention of the premium fuel requirement. All three RX450 versions (FWD, AWD, AWD F-Sport) note that premium fuel is required, which is a stated specification. However, I am hoping that my switch to Shell Premium from a store brand Regular gas will improve driveablity in my RX350 (although I have no way to prove it, easily).

Macs4RX

Recently I was driving by a Shell gas station (Top-Tier gas retailer) and saw that its underground tanks were being refilled by an independent tanker truck so I decided to stop and chat with the driver. Here's what I learned:

1. The truck had a 10,700 gallon capacity split into five separate compartments. So this tanker truck had the capability to transport up to five different fuels (regular, mid, premium, diesel). On this particular day he was delivering 7,000 gallons of regular and 1,000 gallons of premium. (Some of the compartments may have a larger volume than others).
2. There were two, large diameter hoses transferring the regular and premium into their two respective underground tanks. The process takes quite a while and there was no indication it was nearing completion when I left after talking with him for about 15 minutes.
3. Earlier in the day the tanker was initially filled at a large, gasoline terminal facility about 80 miles away. The driver said this is where many of the different companies (Shell, Chevron, Exxon/Mobil, Valero, store brands) get their gas. The bulk gasoline is all the same for all the different companies.
4. At the terminal, when the driver is ready to take on fuel he enters a computerized code which uniquely identifies the brand (Shell) and grade (Premium). Although all the bulk gasoline is the same it is at this point that the company specific additives are added, presumably by injecting/infusing them into the bulk gas.
5. Is the bulk gas, itself, comprised of separate regular and premium streams? I'm not sure but think so because I've read that the premium fuels, while not having a greater energy content per gallon, do have a different blend of hydrocarbons so it would make sense that there would need to be at least two different bulk gasolines.
6. Premium fuels, therefore, may differentiate themselves in two ways from Regular gasoline. They may have a different blend of basic hydrocarbons (possibly smoother burning hydrocarbons) and they most certainly have specialty additives (most likely expensive chemicals intended to keep our engines clean).
7. As for myself, I'm using Shell V-Power Nitro+ Premium 93 octane. Engine seems to run well on it. Ymmv.

s4iscool

interesting, thanks for sharing! Ive been fine with top tier 87, just like the car asks for.

daveylin

So this has happened twice now in the last couple days... I need to take the car in but was wondering if anyone else has experienced this... I think its different from the hesitation issues which I have as well.

On the freeway twice, the transmission seems to have gotten stuck on a low gear and wouldnt change... the rpms got to around 4k and then jumped awkwardly down like it was skipping gears. I had this same thing happen on my old accord before the transmission blew...

For what its worth, its a 350 f sport with 2800 miles.