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I have a 2017 RX and have been frustrated with the hesitation on acceleration that everyone refers to in this thread. It goes away in Power Mode but is always there in Normal mode. Dealer said there was no TSB and that I needed a fuel cleaner treatment which can't be the case because the problem would be there in Power mode as well. I knew it was computer related and I saw the conversation regarding the Powertune module that you plug into the diagnostic port under the driver side dash. I was skeptical to say the least but for $80 from Amazon I thought why not, what do I have to lose? If it doesn't work I'll just ship it back. Well, I am very happy to say the problem is now RESOLVED! All hesitation on low to medium acceleration is gone. FINALLY!
I hope this helps others with the same problem. Good luck!
I have a 2017 RX and have been frustrated with the hesitation on acceleration that everyone refers to in this thread. It goes away in Power Mode but is always there in Normal mode. Dealer said there was no TSB and that I needed a fuel cleaner treatment which can't be the case because the problem would be there in Power mode as well. I knew it was computer related and I saw the conversation regarding the Powertune module that you plug into the diagnostic port under the driver side dash. I was skeptical to say the least but for $80 from Amazon I thought why not, what do I have to lose? If it doesn't work I'll just ship it back. Well, I am very happy to say the problem is now RESOLVED! All hesitation on low to medium acceleration is gone. FINALLY!
I hope this helps others with the same problem. Good luck!
2017 RX had THREE versions of a TSB to remedy the hesitation. It's purely a transmission software mapping problem, not a fault just designed for low fuel consumption. The TSB changing the mapping and the hesitation in Normal mode should be gone.
I always wondered if one of those would work because even after all the TSBS the hesitation is definitely still there, I tend to always drive in sport mode. What’s the name of the one you used ?
Originally Posted by patcic
I have a 2017 RX and have been frustrated with the hesitation on acceleration that everyone refers to in this thread. It goes away in Power Mode but is always there in Normal mode. Dealer said there was no TSB and that I needed a fuel cleaner treatment which can't be the case because the problem would be there in Power mode as well. I knew it was computer related and I saw the conversation regarding the Powertune module that you plug into the diagnostic port under the driver side dash. I was skeptical to say the least but for $80 from Amazon I thought why not, what do I have to lose? If it doesn't work I'll just ship it back. Well, I am very happy to say the problem is now RESOLVED! All hesitation on low to medium acceleration is gone. FINALLY!
I hope this helps others with the same problem. Good luck!
Dealer work order states software update LSB-032-19 OP code 800269. I found the information on this web site, printed it and gave to my service advisor.
what was the TSB number? and can you tell us what has improved?
Hotrod70 is on the money, just make sure it's the one issued in Sept 2019 wih Rev at the end. They had a couple of goes with that TSB to get it right apparently.
Hotrod70 is on the money, just make sure it's the one issued in Sept 2019 wih Rev at the end. They had a couple of goes with that TSB to get it right apparently.
GSFRX350, that is very important information. I have done it in Canada in August 2019 and I am very disappointed with the result.
For Canada it was "L-TCI-5285" which is equivalent of "L-SB-0032-19" in US. TSB was dated July 2019.
So you are saying that there is newer revision of "L-SB-0032-19" which was released on September 2019?
Can you post where can I get a copy of it? (with the rev)
The module is by PowerTune but here is an update. They say the unit goes into learning mode for the first few weeks and I think a little bit of the hesitation MAY be back after it was totally gone when I first plugged it in. I will test it again today and report back. If it does come back, I will reset it, remove it and put it back in and see what happens.
The module is by PowerTune but here is an update. They say the unit goes into learning mode for the first few weeks and I think a little bit of the hesitation MAY be back after it was totally gone when I first plugged it in. I will test it again today and report back. If it does come back, I will reset it, remove it and put it back in and see what happens.
Stay tuned.
I had all of the TSB applied. Each time the issue significantly improved, but for only about a week. Then it came back.
GSFRX350, that is very important information. I have done it in Canada in August 2019 and I am very disappointed with the result.
For Canada it was "L-TCI-5285" which is equivalent of "L-SB-0032-19" in US. TSB was dated July 2019.
So you are saying that there is newer revision of "L-SB-0032-19" which was released on September 2019?
Can you post where can I get a copy of it? (with the rev)
I had the TSB done back in May. On a road trip this week I started to notice occasional hard downshifts/surges on deceleration and more pronounced upshifting at high speeds -- particularly when going uphill. So while on the road trip I took the car to the Lexus dealership that sold me the car. A senior tech (18 years with Lexus) road with me for a 17-mile test drive. Unfortunately I couldn't reproduce the upshifting/uphill behavior, but I could reproduce the "surge." In his view that behavior wasn't abnormal. Let me be clear -- the tech wasn't trying to brush me off. He offered to keep the car and have a regional expert come in to take things further.
I asked him if the TSB was done correctly. He explained that it was. He also ran a complete diagnostic on the RX and showed me the results (all normal; no codes). The transmission was calibrated correctly.
The tech did ask me if the battery had been disconnected lately. I said no. He then mentioned that a disconnect will trigger a transmission relearn procedure. So I asked him to disconnect my battery to trigger a relearn. He did. I've driven ~10 miles since then and the transmission behavior is much improved.
One thing that's been troubling me is why the '17 RX shifts so differently than the 8-speed in my '20 ES. I thought that Lexus used the same Aisin 8-speed in all applications, but I was wrong:
I had the TSB done back in May. On a road trip this week I started to notice occasional hard downshifts/surges on deceleration and more pronounced upshifting at high speeds -- particularly when going uphill. So while on the road trip I took the car to the Lexus dealership that sold me the car. A senior tech (18 years with Lexus) road with me for a 17-mile test drive. Unfortunately I couldn't reproduce the upshifting/uphill behavior, but I could reproduce the "surge." In his view that behavior wasn't abnormal. Let me be clear -- the tech wasn't trying to brush me off. He offered to keep the car and have a regional expert come in to take things further.
I asked him if the TSB was done correctly. He explained that it was. He also ran a complete diagnostic on the RX and showed me the results (all normal; no codes). The transmission was calibrated correctly.
The tech did ask me if the battery had been disconnected lately. I said no. He then mentioned that a disconnect will trigger a transmission relearn procedure. So I asked him to disconnect my battery to trigger a relearn. He did. I've driven ~10 miles since then and the transmission behavior is much improved.
One thing that's been troubling me is why the '17 RX shifts so differently than the 8-speed in my '20 ES. I thought that Lexus used the same Aisin 8-speed in all applications, but I was wrong:
'17 RX FWD: U881E
'17 RX AWD: U881F
'20 ES: UA80E
The transmission maybe the same but the software mapping is what makes the decisions on when/how it changes. The RX is a heavy thing and the mapping is heavily aimed at fuel economy in normal mode.
The hard downshifts are normal in the RX, I'm in Australia with a Jap built car and it does it, only occasionally and quite random. I regularly go on a 1,400 km round trip to visit family, same road everytime and just out of the blue a hard downshift will happen. It's so random and infrequent that I haven't bothered having it looked at.
Yes disconnecting the battery will reset the transmission, it learns your driving style and adapts the gear changes to your style. Do you have more than one person regularly driving your car? If so and one person is a hard driver (fast, large throttle openings) and the other is gentle (slow, feathering the throttle) it will screw up the learning process and the transmission may struggle to suit both of you.
I agree that it seems that the transmission is programmed to reach the highest gear ASAP (in normal mode).
The hard downshifts are definitely intermittent. I guess what surprises me are the vast differences in shifting between my RX and ES. The ES shifts like butter. But you're right -- they're different vehicles!
