Hesitation problem at various speeds (TSB info post #159)
01-19-19, 06:49 AM
#991
Just got my car back from the dealer and I am 100% satisfied with this fix. My car doesn’t feel jerky and no hesitation on acceleration now.. The tech didn’t do the battery reset thing so I did lose the Sport Plus mode. Went back right away and they fixed it.. I did lose some of my car settings but not the radio presets. Car is a pleasure to drive now.
My dealer didn’t know anything about this TSB lol.. luckily I printed it out and showed them. This was done at Lexus of Royal Oak in Calgary..
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BensonTT (01-19-19)
01-19-19, 11:03 AM
#992
Lead Lap
Lots of people seem to have the wrong idea about what an Adaptive Transmission is.
An adaptive gearbox does indeed learn the style of the driver - but over minutes, or a small number of shifts, not over a long period of time such as thousands of miles since the last ECU reset.
Essentially, if you start to brake hard and accelerate hard it'll automatically start to go into a sport mode where it delays upshifts and downshifts earlier. Then if you back off to a more economical pace the gearbox will automatically respond by shifting up earlier and generally using higher gears. This is what adaptive transmission means.
Lexus does not indicate anywhere that they use this type of automatic adaptive transmission. In fact, we know our Lexus' can manually adapt the transmissions when we manually switch between Eco, Normal and Sport modes. But this process is not automatic.
I know that the ECU reset procedure people frequently mention can potentially make a difference in perceived performance for a little while by resetting long-term memory values such as idle speed, throttle/fuel usage, spark, trim gain values on the injectors, sensor and actuator values as well as diagnostic trouble codes. But one thing the values do not seem to include is shift points. Resetting the ECU is not something you should do as a matter of routine maintenance. All of these values saved by the ECU are largely beyond the control of the driver.
While some very expensive or sporty cars have had automatic adaptive transmissions in the past, it is an apparent myth that the RX 350's transmission learns and responds automatically to the driver's driving style.
Think about this hypothetical for a moment.... If I'm in the market for a used 2017 RX 350 and I've found two sellers with ~ 50,000 miles on each. One was driven by a grandmother slow as can be, the other was driven by a 22 year old speed demon who constantly floors the vehicle. Are you saying the RX 350 driven by the speed demon would appear to perform better than the RX 350 driven by grandma? I can't imagine Lexus would knowingly allow this type of ECU behavior to hamper grandma's ability to resell her car or drive it safely by hampering it's performance. The buyer would think there's something wrong with grandma's car (even though it's the better buy) and buy the ragged on speed demons car instead simply because it performs better? That just cannot be right.
This whole adaptive transmission thing is a myth it's time to dispel.
The ECU reset procedure does not change transmission behavior, but it does temporarily change behavior of other parts of the engine mostly relating to fuel delivery.
An adaptive gearbox does indeed learn the style of the driver - but over minutes, or a small number of shifts, not over a long period of time such as thousands of miles since the last ECU reset.
Essentially, if you start to brake hard and accelerate hard it'll automatically start to go into a sport mode where it delays upshifts and downshifts earlier. Then if you back off to a more economical pace the gearbox will automatically respond by shifting up earlier and generally using higher gears. This is what adaptive transmission means.
Lexus does not indicate anywhere that they use this type of automatic adaptive transmission. In fact, we know our Lexus' can manually adapt the transmissions when we manually switch between Eco, Normal and Sport modes. But this process is not automatic.
I know that the ECU reset procedure people frequently mention can potentially make a difference in perceived performance for a little while by resetting long-term memory values such as idle speed, throttle/fuel usage, spark, trim gain values on the injectors, sensor and actuator values as well as diagnostic trouble codes. But one thing the values do not seem to include is shift points. Resetting the ECU is not something you should do as a matter of routine maintenance. All of these values saved by the ECU are largely beyond the control of the driver.
While some very expensive or sporty cars have had automatic adaptive transmissions in the past, it is an apparent myth that the RX 350's transmission learns and responds automatically to the driver's driving style.
Think about this hypothetical for a moment.... If I'm in the market for a used 2017 RX 350 and I've found two sellers with ~ 50,000 miles on each. One was driven by a grandmother slow as can be, the other was driven by a 22 year old speed demon who constantly floors the vehicle. Are you saying the RX 350 driven by the speed demon would appear to perform better than the RX 350 driven by grandma? I can't imagine Lexus would knowingly allow this type of ECU behavior to hamper grandma's ability to resell her car or drive it safely by hampering it's performance. The buyer would think there's something wrong with grandma's car (even though it's the better buy) and buy the ragged on speed demons car instead simply because it performs better? That just cannot be right.
This whole adaptive transmission thing is a myth it's time to dispel.
The ECU reset procedure does not change transmission behavior, but it does temporarily change behavior of other parts of the engine mostly relating to fuel delivery.
ECU reset procedure, more precisely PCU/TCU is not a routine maintenance item. Typically this is reserved for troubleshooting, when the car is not behaving to the inputs of a driver as they commanded it. Dealer Techs usually use their scan tool (techstream etc), other makes do have non-scan tool sequences methods, but nothing solid appears to be available for Lexus's in general (however if you have access to the workshop manual or Alldata subscription they list alternate methods). With this particular topic in mind, being under warranty, why even bother fiddling with a reset, take it in, let the techs know of the problem and show em the TSB. If their reprogram doesnt solve it, then maybe explore other methods.
Adaptive transmissions as far as I know exist, but not in the way most people believe. Its not like the damn thing uses "quantum processing" (I chuckled at the thought). For the most part is axial and directional sensors, the mode buttons, and throttle and transmission maps that are assimilated to presets. Some people like driving like a grandma, and thats their normal mode, others drive like speed demons thats their normal. No one however is purchasing an RX thinking this will take on the one lap of their local circuit so I doubt Toyota Corp cares.
Mind you this is older then current gen transmissions from BMW:
As with automatic transmissions to date, the automatic transmissions GA6HP19Z and GA6HP26Z offer the choice between a comfort program and a sport program. The adaptive transmission control (component of electronic transmission control) adapts the shift characteristics of the comfort program and sport program to the driver's wish and the driving situation. In both programs, the adaptive transmission control changes from a basic map to a performance-orientated map, as required:
·Comfort program in selector lever position "D" The comfort program is based on 2 characteristic maps: The XE map (extreme economy) and the E map (economy). The EGS control unit normally selects the economical XE map (= basic map). In case of particular demands (e.g. load requirements), the system will change to the performanceorientated E map. If the input signals change in favour of a more "gentle" driving style, the system will change back to the more economical XE map.
· Sport program in selector lever position "M/S" The sport program effects dynamic, sporty shift characteristics. In the sport program, there is the basic S map (sport) and the performance-orientated XS map (extreme sport). If an extremely dynamic driving style is called for, the system will change from the S map to the performance-orientated XS map.
The adaptive transmission control takes the following demands into account: driver type, driving uphill or trailer towing, driving downhill, braking deceleration and automatic upshifts, winter program · Adaptation to driver type The adaptation to the driver type is made using the values kick-fast, cornering detection, brake evaluation and constant-speed travel. The driver-type adaptation is restarted each time the vehicle pulls away from a standstill.
Kick-fast If the accelerator pedal is depressed rapidly, the shift program is changed accordingly. This is achieved by the detected accelerator-pedal value being compared with threshold values in the EGS control unit. The result of this comparison is the proposal of one of the two possible adaptation programs (XE or E in comfort program, S or XS in sport program).
Cornering detection Cornering detection reacts to the vehicle's lateral acceleration with an indirect adaptation to the driver type. Lateral acceleration is considered an indirect statement of the preferred driving dynamics and does not cause an immediate gearshift reaction (downshifts when cornering could negatively affect driving stability). The lateral acceleration is calculated by means of signals from the wheel speed sensors on the front and rear axles and from the yaw rate and the road speed.
Brake evaluation The braking action is evaluated in a similar way to "kick-fast". The braking deceleration is measured and compared with threshold values in the EGS control unit. The result of this comparison is the proposal of one of the two possible adaptation programs (XE or E in comfort program, S or XS in sport program).
·Comfort program in selector lever position "D" The comfort program is based on 2 characteristic maps: The XE map (extreme economy) and the E map (economy). The EGS control unit normally selects the economical XE map (= basic map). In case of particular demands (e.g. load requirements), the system will change to the performanceorientated E map. If the input signals change in favour of a more "gentle" driving style, the system will change back to the more economical XE map.
· Sport program in selector lever position "M/S" The sport program effects dynamic, sporty shift characteristics. In the sport program, there is the basic S map (sport) and the performance-orientated XS map (extreme sport). If an extremely dynamic driving style is called for, the system will change from the S map to the performance-orientated XS map.
The adaptive transmission control takes the following demands into account: driver type, driving uphill or trailer towing, driving downhill, braking deceleration and automatic upshifts, winter program · Adaptation to driver type The adaptation to the driver type is made using the values kick-fast, cornering detection, brake evaluation and constant-speed travel. The driver-type adaptation is restarted each time the vehicle pulls away from a standstill.
Kick-fast If the accelerator pedal is depressed rapidly, the shift program is changed accordingly. This is achieved by the detected accelerator-pedal value being compared with threshold values in the EGS control unit. The result of this comparison is the proposal of one of the two possible adaptation programs (XE or E in comfort program, S or XS in sport program).
Cornering detection Cornering detection reacts to the vehicle's lateral acceleration with an indirect adaptation to the driver type. Lateral acceleration is considered an indirect statement of the preferred driving dynamics and does not cause an immediate gearshift reaction (downshifts when cornering could negatively affect driving stability). The lateral acceleration is calculated by means of signals from the wheel speed sensors on the front and rear axles and from the yaw rate and the road speed.
Brake evaluation The braking action is evaluated in a similar way to "kick-fast". The braking deceleration is measured and compared with threshold values in the EGS control unit. The result of this comparison is the proposal of one of the two possible adaptation programs (XE or E in comfort program, S or XS in sport program).
https://www.gearsmagazine.com/resour...5121232000.pdf
https://gearsmagazine.com/magazine/g...but-different/
01-19-19, 03:08 PM
#994
Pole Position
Machine13 <---- Who is this guy???
He keep talking about official Lexus documentation, website, brochures, tech bulletins, etc said ,but does he even own a 4th Gen RX? LOL
He keep talking about official Lexus documentation, website, brochures, tech bulletins, etc said ,but does he even own a 4th Gen RX? LOL
And so what if I was hoping to see something from an official Lexus source? Wouldn’t that be prudent before believing what you read on the internet?
01-20-19, 02:59 AM
#995
Intermediate
Actually cool saber, a battery reset is quite a common procedure, and is done when you update/change software. The 4th step from the hesitation TSB says “Perform a 12V battery reset on the vehicle after software update.” Additionally, there is a big red note that says, “This step is important as certain options may become unavailable during software update.”
01-20-19, 09:49 AM
#996
Lead Lap
Actually cool saber, a battery reset is quite a common procedure, and is done when you update/change software. The 4th step from the hesitation TSB says “Perform a 12V battery reset on the vehicle after software update.” Additionally, there is a big red note that says, “This step is important as certain options may become unavailable during software update.”
01-20-19, 10:16 AM
#997
Intermediate
While I think we are in agreement, remember that a Technical Service Bulletin is not a routine service item. Its not a prescribed line item an SA would recommend say during an oil change. Its primarily an owner complaint that has been verified, resolved, and sent out via TIS to be used to remedy owners complaints. However, anecdotal evidence has suggested that if you want to avoid a trip to the dealer, and are DIY a fix to your issues, a reset seems to be the way to go. In addition, the other thing here is a the TSB, also maintains that this issue must be rectified by a system software update in addition to a reset.
01-21-19, 05:05 PM
#998
No, I'm ultimately arguing that resetting the ECU does not change transmission behavior. This is the main point I'm trying to make. Do you agree or disagree with that statement, or don't really know for sure?
I am arguing that the transmission does not learn, per-se, not in any meaningful sense of the word learn. It obviously responds in real-time to real-time inputs from the driver and other various road conditions such as wheel slippage, etc., but nowhere does any official Lexus documentation say it learns the driver's style, and thus, records data values that can be deleted with an ECU reset.
I am arguing that the transmission does not learn, per-se, not in any meaningful sense of the word learn. It obviously responds in real-time to real-time inputs from the driver and other various road conditions such as wheel slippage, etc., but nowhere does any official Lexus documentation say it learns the driver's style, and thus, records data values that can be deleted with an ECU reset.
You were saying there's mention in brochures, websites, manuals or whatever stating the car has an adaptive transmission - maybe because it's becoming so common it's not news worthy, it's just another part of the car's technology that would get lost on most people. Plenty of tech in the engines too but there's no mention about it anywhere. I mention before that the AWD system is not mentioned in the manual, you said it is but it's not mentioned how it operates, just says it's there, that's all.
Over on the IS forum they talk about the adaptive transmission in their cars - are they wrong too. Again there is no mention on the Lexus website, brochure, manual, but again plenty of people resetting their transmissions. Here's the links to a couple of threads on the IS, also attached a photo of my service invoice where it says "rest transmission memory".
Can all these people be wrong, dealers making up stories about resetting the transmission, most of the comments on here are from people in the US/Canada but I'm in Australia, are all the dealers in a big world wide conspiracy pretending there's an adaptive transmission when there isn't.
https://www.clublexus.com/how-tos/a/...our-ecu-363500
https://www.clublexus.com/forums/is-...ml#post2539716
Last edited by GSFRX350; 01-21-19 at 05:13 PM. Reason: Add Image
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Cocal (01-22-19)
01-22-19, 03:15 AM
#999
Intermediate
Really interesting. Didn’t see the attachment. Do you know how they reset the transmission memory? I would like to be able to reset it myself - maybe by pulling fuses.
01-22-19, 04:14 AM
#1000
I have trouble uploading attachments for some reason, works sometimes and other times it doesn't.
01-22-19, 04:16 AM
#1001
01-22-19, 04:24 AM
#1002
Intermediate
No I didn't ask them. Well you could try https://www.clublexus.com/how-tos/a/...our-ecu-363500, highly likely to be the same.
I have trouble uploading attachments for some reason, works sometimes and other times it doesn't.
I have trouble uploading attachments for some reason, works sometimes and other times it doesn't.
01-22-19, 12:10 PM
#1003
[QUOTE=rxtimes2;10416499]
If you remember, did you have to redo all of your settings after they did the transmission memory reset?[/QUOTE
No, but the dealer most likely used an electronic tool like the one in the link I provided.
If you remember, did you have to redo all of your settings after they did the transmission memory reset?
No, but the dealer most likely used an electronic tool like the one in the link I provided.
01-23-19, 04:30 PM
#1004
Lead Lap
There not just pulling off the battery terminals, the dealership usually has the official Toyota techstream scan tool. All you need is the vehicle OBD port and a couple of clicks and you can command basically every system and function tests the vehicle is designed with. Plus, since modules are often coded to the VIN or may need power at all times, the dealership would be equipped to keep a secondary source of power hooked up to the car if required.
02-04-19, 05:57 AM
#1005
Driver School Candidate
I HATE this transmission!
Is it me, or is the RX350’s transmission just pure garbage? Had this car for three years now and I still can’t get used to the timing and shift points. It’s just so unpredictable and rough at times especially when taking off and at low speeds. I am car-sitting my parents’ 2008 ES350 and it still drives like a dream. The engine and transmission work beautifully together and reminds me why I wanted to buy a Lexus three years ago. So disappointed now and likely will never purchase another Lexus or even a Toyota product. Will likely check out the new Acura MDX when it comes out or go back to a German brand. Surprisingly enough the Audi Q5 we replaced
the RX350 with that had 100k miles was the most reliable car we ever had next to a Honda Accord we had for 130k. I hope the ‘18 and ‘19 years are better than my ‘16. That should be enough time to fix the first year problems.
the RX350 with that had 100k miles was the most reliable car we ever had next to a Honda Accord we had for 130k. I hope the ‘18 and ‘19 years are better than my ‘16. That should be enough time to fix the first year problems.
Last edited by technodis; 02-04-19 at 06:07 AM.