Rxyen

Did you try clearing the Transmission ECU memory (disconnecting the battery for > 30 minutes)? The dealer should have done it, but in case they didn't.

Cocal

I don't know, but will ask to do that when next in for service, Thanks!

johnhey

I have done it with no effect.
I disconnected the battery overnight but still did not loose any settings (like radio etc)
Talked to Lexus engineer about it and was told that it is not the case anymore.
newer Lexus(s) are equipped with capacitors which keeps the information even if you disconnect the battery. It may be erased if the battery disconnected for days. but for few hours those capacitors have enough juice to keep the settings.

Rxyen

Oh okay, that's good to know. So is dealer or Techstream the only way to reset the transmission learning?

rxtimes2

That makes a lot of sense. With one of the TSBs that I had done, I asked if the battery had been disconnected, and was told that they just shorted something out to accomplish the same thing. I don’t remember what he said they shorted - maybe the positive battery wire to ground would unload the capacitors. I will have to ask again. If I ever get out of the house.

ravenuer

With the electronics in todays cars, I would be REAL careful about shorting battery cables.

johnhey

that is correct, they erase it with Techstream at dealer.

diggdyone

Thanks Kain B., Let me state this about my journey with the hesitation.

Race Trac or QT Top Tier 93 octane fuel only (when in Ga.)

Brought the RX a year ago;
it would buck when down shifting (hard braking on the highway) and up shifting (hard on the gas from a roll)
Also it would gear hunt as you drove up and down hilly roads of Georgia
It would hesitate when hitting the gas from a stop

Did the 1st TSB
Bucking stopped ....
gear hunting stopped in SPORT MODE ONLY...
hesitation was still there in all modes (Dangerously Bad)

Did the 2nd TSB
hesitation stopped...for a week
gear hunting still in normal mode

Once a week disconnect the battery over night
hesitation stops for a week
Gear hunting in normal

RedLine on a full tank and battery disconnect over night
RX RUNS HARD...in SPORT MODES
Gear hunting STOPPED in all modes




Chevron conc. plus on a full tank NO battery disconnect
Running HARD in all MODES




800 MILES LATER this RX is driving the best it ever has AND I will be using REDLINE once a month and
Chevron cont. plus twice a month......Small price to pay for the joy this RX gives me....
If this didn't work I could see a SRT or Jeep Trackhawk replacing the RX......they are fast and fun



But, for now my wife is flying in the RX like a slow jet.


I use this for FAST FUN....

DMPesso

I was debating trying these octane booster and fuel injector cleaners. They always added a little boost to my older cars, didn’t think it would a newer car. Are you using it on an empty tank and then filling up though? That’s what I always did. I’m anxious to add some now I have a bottle in the car but the tank is almost full. I was also debating trying to disconnect the battery every week like you do as the car drives amazing when it’s still “learning”. I heard there is an easier way to reset the ECU with the fuse rather then disconnecting the battery every time physically. Aren’t you losing your radio settings each time you do that? That was the only thing stopping me, losing settings sounds annoying.

ericsan13

Yikes...at an additional cost of $30 per month for those three bottles it may make sense to just trade in for the buttery smooth hybrid.

Cocal

That may explain why I've never had any of these problems, but I only use 94 octane from the 1st fill up.

diggdyone

No problem with radio resetting after removing both cables...which is weird. I reset over night only. My plan is to keep this regiment of fuel cleaners and treatment going for 6 months then see how she works without them. As for cost...gas is cheap now $1.50 and Walmart sells the Chevron for $5. "What do you have to lose"......

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!

GSFRX350

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.

DMPesso

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 ?