i received a similar call - the person left a voicemail and said there is a an "open service recall for an engine software update."

i checked the lexus site with my VIN and only say the update for the parking sensor issues with some car washes.

i just assumed they were trying to get me to go to dealership to upsell me on stuff..

it would be interesting if there was really some update with the gear searching..

 

which year and model rx do you have? Does yours gear hunt in sport mode also? I only notice this in normal mode. Definitely the transmission software.

It will, especially in the beginning until the car gets used to the gas. Then it will start lowering RPMS trying to learn your driving habits and save gas. The first time I ever put 93 in the car it was driving amazing. It’s really stupid the way they designed it. Sport mode eliminates all issues. Every time I fill the car up with different gas it’s a little more responsive in normal mode until it gets adjusted.

 

For what years? there is already a TSB for the 2016-2017. Wouldn’t be surprised if it’s the same one but Lexus has to pay for each year to upgrade since it has to do with the EPA and MPG

 

Have to wonder if/how the new TSB will differ from the existing one. Wouldn't it be wonderful if it permitted the ECU to select sport mode as a permanent option? Or reset the shift rpm signals to higher values, accomplishing the same effect?

 

Yes it's dumb the setting is not retained between starts.

 

There is nothing wrong with the transmission itself, as some have stated in Sports mode it's fine and if you drive gently, small throttle openings she's always silky smooth. It's purely the software mapping with Lexus aiming for that good fuel consumption figure. Lexus are more concerned with the fuel consumption figures then driveability as most of their customers I would say drive the RX gently and don't really notice the hunting or doesn't bother them. Have you tried having the stereo loud and not looking at the tacho, you'll find without the engine noise the tranny is still hunting but it really doesn't matter as forward progress is fast and smooth. Seeing the tacho and hearing the engine can play on your mind. I'm not saying it's correct the way they program it and if you want that refined feel without the stereo loud the hunting is hard to take sometimes.

Anyone with concerns about their car should try the TSB or even just get the dealer to reset the tranny, makes a world of difference especially as it appears some of you have been switching fuels and probably like I did kept trying to out think the tranny by changing your driving style. My RX was a used one, 18,000 km on it, I don't know what the tranny had learnt from the previous owner but when I first drove it for months I kept changing fuel tiers and changing my driving style, more throttle at certain points to try to keep the revs up for example, so all along the tranny is trying to adjust to your driving style/fuel but then I kept changing my style/fuel. It appears it was just messing up the learning process. When I had my first service I asked about the hunting, they reset the tranny and it was a different car, it will still on occasion change gears when you don't want it too, mainly when turning at intersections and there's a hill going upwards but it's been far, far better.

 

I also bought a 2016 RX 350 with 15,000. After reading these Lexus Forum posts, I requested the dealer to reset the ECU Transmission program. My results were exactly as the prior poster described--like a new car. The 8 speed transmission still does search too frequently for the "right" gear, but the reset improved performance. If I could permanently select sport mode, I'd we very happy. Meanwhile, I did switch to 91 octane gas and that is as close as one can get to ideal performance. Thanks again to the forum posters, who provide useful observations and solutions.

 

I'm well into my second tank of Shell 93 octane. The hesitation from (apparently) the transmission may be a little better, or maybe I just imagine it. Bot WOW the fuel mileage! This was on a 350 mile trip yesterday, 175 miles out and then back home. On the way home, I learned that a bit of tailwind had helped me on my way out, as the mileage dropped to 26.5 on the return trip. So maybe 1 mpg of tailwind. But obviously the engine is performing much more efficiently with the 93 octane.

 

Oh for sure especially on the highway you can get some great mileage. The MPG on my f sport in New York City streets I only get around 13-14 MPG. Absolutely horrible, but I still love the car. I got the same mileage on my 2001 GS430 which is a V8. This car shines on the highway with the 8 speed, gets excellent mileage and performance. The f sport wheels decease mileage, they are definitely heavier then stock 18s. Had I known about the hesitation issues I would’ve waited for a 450 f sport. Worth it for that and double mpg in the city

 

Been followinfg your post and I am really hoping there is a fix for a Canadian car. My recently purcahsed 2016 Rx has the same issue with hesitation as described above. I am going in on Friday to have it tested.. very close to ending my warranty (80,000 km) however i beleive tranny warranty is upto 110,000 km.

Thanks for all the information and the details.

 

The US TSB can be found at post #159 in this thread. The TSB lists the vin #s of cars which can be reprogrammed. Don't know if Canadian TSB # is different. Still, the US TSB lists vin #s for cars that were manufactured in Ontario, so it should still indicate if your car's vin # applies.

 

I purchased a 2016 RX350 in March and continued to have hesitation in the transmission at various speeds. I took the car back to Newport Lexus and they said they were unable to duplicate the error. Since then I have taken the car to a different Lexus Dealer and was informed that the previous owner had the ECU reset and would not help my situation. In May, my transmission was replaced due to harsh engagement in the transmission. It was a very frustrating process but eventually after having the lead mechanic ride in the car with me, He was able to identify the issue and replace my transmission.

 

Wow you actually got them to replace the transmission. This is insane that this car has such horrible transmission issues. What dealer replaced it for you? Is it perfect now that you got a new one? What was the exact issues you had? I definitely feel like the transmission in this car is unreliable and won’t last.

 

Yes, once the head mechanic rode with for less than 3 minutes he said this is a harsh engagement of the Transmission turn around I’ll write this up so your transmission can be replaced.
**side note, I documented every time my car hesitated and added the speed I was going so I had a pretty lengthy letter due to the issue occurring several times a day from he 2nd day of purchase til May. It occurred always between 15 and 20mph. Unfortunately I never had to whip that out due to the mechanic identifying the issue. Also I purchased my car at 35K miles in March 2019.

My Transmission was replaced at the Cerritos dealer. Mind you I purchased it at Newport Lexus, the head mechanic was conveniently never there (available) when I brought my vehicle in for my scheduled appointment for them to check it out and requesting to meet with the head mechanic . I was very disappointed with the service at Newport. Cerritos was very attentive and also repaired other things like the timing chain and other stuff due to oil leaking. I also started the process for a lemon lawsuit and have been in communication with corporate since April.

 

Makes you think all these issues with hesitation people are having could mainly just be a bad transmission. It is the first 8 speed transmission ever by Aisin. By harsh engagement do you mean just a typical hard shift? Only between 15-20 MPH, never at other steeds? Was it consistent?