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Toyota/Lexus transaxle shift delay



  • billranbillran Member Posts: 113
    I was talking about formal complaints registered with the NHTSA. If this were the widespread problem you want so badly for us to believe, and it affected two million cars, there would certainly be a long list of complaints on that site. But there is not. If even one percent complained, there would be 20,000 complaints. Yet we cant even find anything even close to 1000.

    Also, there is no "Formal Admission by Toyota", at least not that I am aware of. Could you direct me to the text of this admission? I believe that statement is flat out untrue. There is a TSB and nothing more.

    And finally, I base my personal opinions on this; I, and two other people I know have cars that drive flawlessly. And, since there are two million similar drivetrains out there, and a very very small number of formal complaints, it is obvious that the vast majority of owners have no problem.

    On the other hand, posters like wwest, user777 and scoti do not own, and have never even personally driven one of the affected vehicles. Their opinions are apparently based solely on the few people who do report a problem. The motivation to make this issue such a personal endeavor, and post distortions like the one I noted above, is still very curious to me.
  • hylynerhylyner Member Posts: 216
    Before I start---Gentlemen please!! This is not a 'to the death' contact sport, it's just a discussion. Tone things down a bit, or we'll be reminded to by the host!

    To answer your questions User777, no I don't have an affiliation with any automaker. I'm a shift engineer with a local utility--coal fired elect. generation. I am there (off the board)as we speak. (On the other hand, maybe an automaker or three uses our product--does that count??)
    Asking those kinds of questions is getting pretty close to personal--and like Bettersafe says, personal is childish. Besides, it makes about as much sense as asking you, for example, if you work for the competition. Would anything change if you did??

    The same logic applies to your question about 'marginalizing'. If this is true then---when one participant is in favor of an issue--that's OK. But the other side is, using that logic--'marginalizing'?
    I am of one opinion, you are of another. Something incorrect, illegal, or immoral about that?? I don't think so.

    Re lack of helpful info from yours truly. Yes,I have tried on a number of occasions to do just that. Most of the time these have just been ignored. Occasionally there's been a not so subtle reminder shortly thereafter to do just that--ignore--don't respond--or whatever. All that tells me is that some are intent on blocking one side of the discussion. That raises the question of motive--big time.

    Enough said--for now. I've gotta get back to the board. Will finish later.
  • billranbillran Member Posts: 113
    user777, thanks for the links. I think maybe there is a misunderstanding. Those are the well known and often quoted links regarding the hesitation and release of the TSB. I was referring to the comment wwest made above:

    Toyota has now publically announced, admitted, that there is now an inherent delay in downshifting their electronically controlled transmissions and transaxles to "protect the drive train".

    That statement is nowhere to be found in the links you posted. But it does not matter. Because any characteristics that are built into the drivetrain are inperceptable and not a problem for me, my two coworkers, or the other two million owners.

    And I am not saying that there is no hesitation problem at all. In fact as the article you linked states A search of NHTSA records and interviews with Consumer Reports magazine also show owners of other car makes are suffering from the same hesitation problem, including BMW's 3 Series, Ford Explorers and Escapes, and Dodge Durango 4x4.

    David Champion, senior director of Consumer Reports' Auto Test Center in Connecticut, said the magazine's testers have encountered the same problems in the Audi A6 2.7T, the Audi Allroad, the Mazda6 equipped with the V-6 engine, and the Volkswagen Jetta 1.8T.

    But the fact that out of 2,000,000 cars, it is hard to find even 200 complaints (and many of those obvious duplicate posts by the same people) is very significant.

    Thats my opinion, and it is based on the facts.
  • user777user777 Member Posts: 3,341
    hylyner - small world... i do controls work for the power generation marketplace myself; some of my projects are for IGCC customers, perhaps your own.

    it's honestly good to know you don't represent toyota or lexus in some capactity... neither do i!!!

    my motivation is to get to some understanding of the controls / automation aspect of the phenomenon, and also to try to address the human factors side of issues like this one (in other forums, i attack other problems in a similar manner).

    why? because in my work as an engineer, i must apply human factors principles among several others. but also, people frankly don't contemplate the consequences of technology when it conflicts with user experience and actions, usurps operator authority, is difficult for people to form an accurate mental model of its state, availability, operation and limits, it degrades or fails, etc, etc.

    there is nothing wrong with us having differing positions, even when and if at opposite ends of the spectrum; sometimes we actually agree! but this isn't supposed to be "war", point-counter-point.

    when someone says there's been an admission of a hesitation problem, and other people go off refuting the statement on what may constitute "admission" or proper representation of the manufacturer or the method by which the information is disclosed to the public... someone is splitting hairs, and it's obvious... ultimately though, we aren't going to find any common ground or help people going far down that road are we?

    why don't you and i go outside our current mindsets to bring new material to the discussion that may be of assistance to others? this is what we must focus on.

    i have already admitted that i was in part responsible for the other forum becoming "read-only" which is a shame. so i don't want to push that limit again. i think the hosts are expecting us to do a better job of self regulation.

    what say you on the matter?
  • hylynerhylyner Member Posts: 216
    Re your question: "what say you on the matter?"
    My thought: Let's all just do our respective thing here, but with mutual respect for each other. If someone disagrees, say so, but keep the acrimony, brinkmanship, and 'personal' out.
    Look User777, I hold no grudges against anybody, whether they agree with me or not. I don't do 'personal', and I simply ask the same in turn from others. In the cold light of day, what we're talking about here is pretty darn low on the 'importance' scale, so is it really necessary to take cheap shots at others over it?
    If I disagree with something, or see something out of context, or have an opposing view on something, I'm going to say so, while at the same time trying to be sensitive to others about it. Please show where I haven't done so, or tell me if I break that rule.
    Fair enough?

    Re Gas Turbines--I've worked with them on occasion--biggest was a single turbine 40 megawatt plant driven by a nat. gas fired GE Jet Engine (from a 747, basically). Efficient operations, given that both power generation and waste heat were profit centres.(Altho' accellerated depreciation of such plants really helps!!)

    One more thing--I know it wasn't quite the way you said it, but technology does tend to make us all a bit crazy from time to time. No offence was intended--I was just trying to keep it light. Seems every time technology solves one problem, that solution creates three more!
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,481
    Experience has shown that any comments like "you must work for Toyota" are in fact a flame and will be treated as such.


    Shifty the Host
  • scoti1scoti1 Member Posts: 676
    I thought chastising people for not owning one of the affected models is not appropriate as well. It clearly states that this forum is for owners and non-owners in the description of this forum.
  • billranbillran Member Posts: 113
    It was not my intent to chastise you or anyone else scoti. If that's how it came across I apologize. Your opinion is certainly as welcome here as anyones.

    I was simply stating that my own opinion is based on my own personal experience with a car that drives flawlessly, as well as two others I know of personally. That plus the fact that out of 2,000,000 cars, it is very difficult to locate even 200 formal complaints on the NHTSA or any other site.

    I look around here at Edmunds and see that at the current time, there is no one who actually has a problem even posting. And, in the last six months only about 6 or 8 individual owners have even posted that they had a problem at all. Of those, at least some found that the TSB solved the problem. Yet, the debate goes on and on, routinely fueled by speculation and occasional distortion (like the post of the "Official Announcement") from people who have never actually driven one of the cars. And that often goes on for weeks in complete absense of any complaints from anyone who actually owns one of the cars. Those posts are certainly as welcome here as any. I just find it curious. That's just my opinion.

    Others may form their own opinions based on whatever facts they choose to accept or ignore. It is a discussion forum, nothing more.
  • bettersafebettersafe Member Posts: 92
    Attempting to form valid statistics from people who post on Edmunds forums is a challenge !

    I think we could do a psychology PhD on what type of person posts, and for how long, on a forum such as this. An owner, who has already gone to several dealers, several times, without success, will likely come to a forum to complain and to seek other forms of redress. After a week or two, I'd think they would not be lively participants for the simple reason that it is too painful. They are mad/angry/frustrated at the dealer or manufacturer, and every time they open this forum, they reopen the wounds of their frustration. Their blood pressure would be in direct correlation with adding yet another post, or defending their positions. I expect that they might check in each month or so to see if a new TSB or legal action has been generated. {This is what I would do.)

    The people who post regularly seem to curious engineers who seek understanding of the problem, and who are trying to nudge the manufacturer to correct the problem. We enjoy daily banter on the topic. Our motivation does not come from the direct self-interest of having our personal car fixed.

    The bi-polar nature of this and the previous forum are interesting. On one side we have frustrated owners, who tend to be non-technical and who are asking for help....and on the other side we have engineers trying to help. I think this is why we have not yet seen an OBD diagnostic computer used on a misbehaving vehicle, which could produce data to prove/disprove WWest theories.

    Maybe I am an optimist, but I think most people are honest in what they say on the forums. Some (most?) folks are perfectly happy with their vehicles, and some are not. And fewer yet are extremely unhappy with their vehicles.
  • hylynerhylyner Member Posts: 216
    Scoti, Billran's opinion is as valid as anyone else's. Each of us can choose to agree or disagree with it, but censorship isn't our role here. That's up to the host.
    I think everyone would agree there's a huge difference between agressively accusing a poster of being a shill working for Toyota, as opposed expressing curiosity why the same 3 or 4 people want to discuss a problem with a vehicle they don't even own.
    It is quite curious as a matter of fact, and I sometimes wonder about it too, but that's their business, so let 'em 'fill their hearts with joy' if that's the case.
    From my perspective, openly wondering about it isn't accusing them of anything and probably not going to change anything either.
    Matter of fact, a lot of the technical input by the 'non owners of affected vehicles' is excellent, so if it ain't broke, don't fix it. Let 'em fill their boots!!
    That said, can we give recrimination a break, and get back on topic? It's much more interesting, and I believe we will all find it far less stressful.
  • user777user777 Member Posts: 3,341
    getting on the gas when making a turn, similar to the scenario where you slow down in the turning lane to a relatively slow speed, waiting for an opening in traffic to go HARD left into a shopping center...

    i mean, did someone test the theory we may have the engine derating because of yaw-rate detection of VSC.
  • wwestwwest Member Posts: 10,706
    I'm pretty sure I have seen several posts, not necessarily here at Edmunds, about drivers experiencing the extended delay while turning. Obviously the entry to the turn might have invoved a standard TSB circumstance.
  • scoti1scoti1 Member Posts: 676
    The delay while turning has been reported here at Edmunds, too. I recall posters stating they see an opening in traffic, pull into the intersection expecting the car to accelerate only to have it delay with on-coming traffic approaching. But I have also read of the same delay in other situations not involving a turn, such as merging into traffic, trying to speed up to pass a vehicle, etc.
  • wwestwwest Member Posts: 10,706
    The service manager at Lexus of Bellevue told me that the really simply way to disable VSC temporarily was to create an engine fault.

    So I disconnected the MAF/IAT sensor connector on my 2001 AWD RX300 while the engine was running. The engine died almost immediately and wouldn't restart. When I reconnected the MAF/IAT it started right back up but with an engine & VSC failure indication.

    After about 4 drive cycles the indications went out.

    So for any of you that are experiencing the extended delay/hesitation symptom if you want to try and see if VSC is somehow related.....
  • user777user777 Member Posts: 3,341
    I'm still hoping that someone with a significant problem would take their vehicle to the dealer and presuming it's been looked at before, politely ask that the throttle body be swapped out.

    WWEST, the position sensor is essentially a rotary potentiometer. It could have non-linear characteristics at the low end. Just as important, there is a IDL (Idle Switch) which senses Throttle at/near zero. Your shop manuals must show this and the range of Throttle degrees where it is still sensed "closed". It's possible in my mind it is malfunctioning and sensing closed for an entirely too large range of throttle opening.

    It is NOT a "Hall effect" device but rather quite mechanical and low-tech.

    go to

    and click on technical articles. Look at page 3 onward of article 16.

    BTW - lots of good information on that site!
  • user777user777 Member Posts: 3,341
    interesting... it's intuitively obvious i suppost that faulting the Mass AirFlow sensor would fault the stability control function...

    THAT's one of the things I'm writing about when I suggest we step back and consider Human Factors and Complex Systems. I mean, who had a mental model accurate to have believed cause / effect for this one?

    No lying now.
  • hylynerhylyner Member Posts: 216
    Glad to see the discussion back on track.
    FYI,I found the following passage while browsing through the old (now closed) 'Engine Hesitation' discussion.
    There are other options to modify throttle response by mechanical means with DBW systems.
    Here's one way---a quote from a Denso technical publication re accelerator pedal modules in DBW systems:
    "The electric output characteristics of the sensor can be set in accordance with customer’s specifications.
    DENSO provides two types of accelerator pedal modules – resin rod type and iron rod type – to meet customer’s needs."

    For those who question reliablity of DBW systems, because they use less mechanical components, they are considered less susceptible to wear, and generally require less maintenance than conventional systems.
    They are more reliable--but they don't behave like conventional systems.
    Perhaps those who question reliability are confusing reliability with expectations in performance.
    Make no mistake, currently about 60 percent of today's vehicles are equipped with DBW systems.
    Within two to three years this technology will be adopted across the board.
    What we're seeing today are mainly second generation designs.
    Response parameters still need work in just about all systems available today--and for all makes using 2nd generation technology.
    Toyota isn't the only carmaker with this issue.
    No question, there is still much room for improvement in these systems re throttle response under changing conditions.
    We can expect a third generation improvement in response characteristics to be included many 2006 models, and by 2007,there should be improved systems available throughout the industry.
  • hylynerhylyner Member Posts: 216
    Attempting to form valid statistics from people who post on Edmunds forums is a challenge !

    You sure got that right Bettersafe.
    You've shown good reason not to attach validity to at least some (who knows the right number) posted stories about this issue. Information from impeccable sources isn't always impeccable!!
    However, in line with what I've advocated many times re objectivity in "Identifying The Problem", It certainly wouldn't hurt to try an get something in the way of useful data from them--where possible.
    Would it make any sense for you folks who profess to be immersed in the issue to develop a check list of appropriate questions for those who do post about problems they're having?
    You could then ask for feedback re those specific questions. (Examples--How is the vehicle used; What are specific hesitation characteristics; Under what/when/where specific conditions does it occur; Principal driver; Vehicle mileage; What options/equipment on the vehicle.......and so on)
    In doing so, over time you might develop consistent "profiles/patterns" which would certainly help focus on possible causes--thus minimize a lot of guesswork which seems to be prevailent in your discussions.
    If you're sincere about finding answers , and not just having fun--as you said "We enjoy daily banter on the topic", this approach might be worth considering.
    If you agree, a good start might be to get feedback from all of us re what might be good questions to ask.
  • billranbillran Member Posts: 113
    Would it make any sense for you folks who profess to be immersed in the issue to develop a check list of appropriate questions for those who do post about problems they're having?

    Thats a good idea hylyner. The only problem with it is that at the current time, there is not a single actual owner posting that they have a problem. Even at the height of activity there were never more than 3 or 4 regular posters who said they were experiencing hesitation, and then a few others who came and went. And, several of those who had the TSB applied, reported that solved the problem.
  • splatsterhoundsplatsterhound Member Posts: 149
    Count me as a someone who has a problem. My dad has a highlander 2004, v6, with a terrible hesitation problem. It bothers him, but he's not the type to complain too much, certainly not bring it to the govt. He's complained to the dealer and they said, "that's the way it is supposed to be." So he lives with it. He's a very cautious and (older) driver so I don't think he cares that much...
  • billranbillran Member Posts: 113
    Has he had the TSB applied? That has been reported as very successful by several people. In any case that is a good place to start.
  • hylynerhylyner Member Posts: 216
    Thanks for the quick feedback.
    It would be helpful for the purposes of this forum if you could provide more detailled information, for example,along the lines of the items I listed above.
    Specifics such as mileage on the vehicle; was it purchased new; did the hesitation start right away or after some miles were run up; does the hesitation come and go; is it more prevailent some of the time; have you driven the vehicle; describe the characteristics of hesitation--upshift, downshift,length of hesitation interval; does it do it with WOT or partial throttle; does it do it when turning; type or style of driving; have any attempts been made to fix it--if so what was done; can you make it disappear by using the throttle in another way........and so on.
    Answers to any or all of these questions would be helpful, and any other info you (or someone else) might think of would be appreciated.
    Hope you can find some time to respond. Thanks in advance.
  • splatsterhoundsplatsterhound Member Posts: 149
    No, he hasn't. The local dealer didn't say there was one. I'll tell him to bring it in and ask. The darn thing drives me nuts when I drive it (that's why I'm here, obviously :) ) The car hesitates so much it's hard to drive in heavy traffic.
  • billranbillran Member Posts: 113
    He might want to ask about this:


    If he asks about that specifically they should be able to find it. It looks like the TSB for 2005 was released in June 05 and perhaps at the time he asked it was either not yet available or not widely known about. I have read several very positive reports about the results of that TSB. Good luck!
  • bettersafebettersafe Member Posts: 92
    I do not understand about TSBs. How comes the owner has to tell the dealer that a TSB exists for his/her car? Isn't the dealer suppose to have some responsibility to know what TSBs exist for which models? Perhaps if it is a safety-related bulletin they send out mailers to owners,,,, but they need do nothing on non-safety-related TSBs?? Who actually pays for the work done under a TSB? The dealer or the manufacturer? Maybe I am wandering off subject, but most drivers do not actively read this Forum. How would they know about the TSB?

    I think my idealism and optimism about a perfect world has just been tainted !
  • splatsterhoundsplatsterhound Member Posts: 149
    I agree: I have a lot of questions about the TSBs. It seems kinda cheesy to have to force the issue onto the Toyota dealer -- they obviously know there is a problem (complaint from my dad), there is apparently a fix available (TSB)...all they have to do is connect the dots. EIther they are lazy or deceptive, and neither is much good.
  • bettersafebettersafe Member Posts: 92
    Way off subject: I have had a Ford Explorer for 8 years with the extended factory warranty. The Ford dealerships (several) that serviced the vehicle always seemed to check to see if there were any TSBs, since Uncle Henry was going to pay the dealer to exercise the TSB. I think the warranty repair and TSBs were a profit-making function for the service department. I appreciated the fact that Ford was taking care of me and my purchase. The vehicle has 140,000 miles and is working like new, except for a radio on/off button that turns "on" by itself. Maybe my vehicle has a resident ghost. . . . (more likely: dust in the on/off switch)

    If a dealership is getting paid to exercise the TSBs, you'd think that they would be happy to inform the owners of any new TSBs that apply to their vehicles.

    What am I missing ?
  • hylynerhylyner Member Posts: 216
    What am I missing? Funny you should ask.
    You may very well be missing the whole story.
    Rarely, when an original owner takes their vehicle to a dealership for service--advises a specific complaint--that the service dept. would fail to look up applicable TSBs for that complaint. The only exception would be a totally incompetent service dept, or some flukey failure to communicate by either party.
    It is my understanding that a policy such as described is one of the 'gospels' in the business, so it's difficult to believe this scenario either didn't happen as posted, or some really exceptional circumstances are involved which haven't been disclosed as yet.

    Speaking of "failures to communicate", I see that my proposed list of questions re hesitation got no response at all. That speaks volumes--it certainly answers some of my questions.
    Rather than dwell on it though, I'll just make a comment or two as a final note:

    When you go to a doctor looking for a solution to a problem--what's the first thing that happens? When you go to a lawyer looking for a solution, what's the first thing that happens? ......and so on. You get my drift.
    Just in case you are reluctant to answer, I'll say it anyway.
    The first thing that happens is the Q and A!! Every time!
    And for complex problems, more Q and A happens!!

    That's why I made the proposal re list of questions--because it hasn't really happened in this discussion--and it's fundamental.
    So somebody please tell us how it's proposed to find answers to the hesitation issue if there's a failure to communicate--ergo--no questions??

    What this profound (contrived??)silence tells me is that there's most likely little or no interest in finding solutions here.
    Either the discussion is little more than an enjoyable daily pastime for some, or the real objective is to cast aspersions upon an automaker.

    Like I said, if it's a sincere and honest objective to find solutions in any controversy, the the most important ingedient is a structured and objective Q and A.
    Why isn't something as fundamental as that happening here?
  • user777user777 Member Posts: 3,341
    agreed - i had the same question re: why noone else was willing to put up some green except myself and bettersafe to see to it that someone got a cool piece of hardware to get objective information about the phenomenon.

    contrived silence and aspersions? let's reel er back in.

    i think you've got the person with the problem that's interested in seeing that there's a fix, and you got the engineers that are theorizing about potential root cause. neither seem very interested in questionare design - but you do. so why don't you WAG one and present it?

    the design of it will have to be such that it captures quantitative information from a qualitative phenomenon with differing levels of understanding of the domain and of wording to describe what they are experiencing. the design will also have to be such that it doesn't lead takers down a path that is not appropriate.

    in my humble opinion - validity in questionaire design is orders of magnitude more difficult to achieve than slogging your way through hooking up an OBD-II interface and capturing some parameters while you repeat the phenomenon, after you figure out how it works.
  • wwestwwest Member Posts: 10,706
    "...proposed list of questions..."

    Q&A...is not constructive.

    Because none of us know which question to ask next until we get a definite answer to the first question.

    Trouble-shooting any problem is like that, you need to explore logical "paths" with a Q&A series and so far none of the paths that have at first seemed like they might yield fruit have.

    Someone please remind me, what was the result of having an individual experiencing the delay disconnecting the battery each and every day?

    Until we can develope a cause and effect by reliably replicating the problem, virtually no progress can be made IMMHO.
  • hylynerhylyner Member Posts: 216
    I said "profound (contrived?)" Profound for sure, but contrived works, especially when it's already been openly advocated--several times BTW ! (Want some cutpasted examples?)
    I said either "fun for some, or aspersions" Either one works. No doubt about it IMO--it's either one or the other--or perhaps both.
    I've seen no evidence of any interest whatsoever in a process of finding realistic solutions, or using a structured approach to get there--starting with some meaningful questions.
    The way I see it, suiting the problem to a solution is the name of this game.
    I'd be happy to put together a matrix of good questions--but I'm quite confident it'll either be completely ignored, or one of the dedicated problem solvers will come forth with some "contrived" reason to refute it.
    So it boils down to a waste of time.
    BTW, I'd be happy to cough up the whole cost of an OBDII, but I can't help but think "Why bother?"
    I'm sorry, but this whole thing is developing a really distinctive aroma.....!
    That's my final answer. ;)
  • wwestwwest Member Posts: 10,706
    "...putting up some green...."

    I have already purchased the 2004 RX330 shop/repair manuals (~$600.00??) but even so I would be willing to participate in an OBD-II tool w/interface.

    1st question: Where, globally, is the person that is certain sure that they are experiencing the extended, hazardous type, engine/transaxle downshift delay?

    2nd question: Is that person capable of using the OBD-II, interface, and laptop to capture the sequence?

    3rd question: can we be sure that capturing the event will not be a long trial and error process?
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,481
    TSBs: These are for dealer FYI. He is under no obligation to perform the TSBs or to tell you about them. Of course, it would generally be good business to do so, but nothing legally or contractually requires the dealer to do anything at all about TSBs if he choses not to.
  • wwestwwest Member Posts: 10,706
    The accelerator pedal position sensors, two of them for redundancy, are both non-contact Hall Effect sensors. VPA is the sensor signal used to monitor accelerator pedal position and VPA2's signal is used to check for validity of the VPA signal. The two voltage outputs, VPA & VPA2 are displaced by at least 0.4 but not more than 0.8 volts. The actual displacement voltage between VPA & VPA2 is an on vehicle "learned" parameter.

    The shop manual seems to indicate that the accelerator pedal has some slack, dead space, backlash. The useable range is 0.8 volts (released) to 5 volts (fully depressed). With the pedal fully released the VPA output voltage can fall as low as 0.5 volts but it appears the ECU will not "take note" of pedal depression until the VPA voltage rises to at lease 0.8 volts.

    After the accelerator pedal assembly (includes sensors) is replaced the vehicle must be run for 15 seconds or more with no activity so the ECU can "learn" the new sensor voltage charactoristics. If there are no diagnostic indications after 15 seconds it is assumed the system is OK.

    The non-contact Hall Effect throttle valve position sensors, VTA1 & VTA2, work exactly the same except there is no backlash or slack. Throttle fully closed position is explicitly defined as 0.69 volts.

    With any persistent diagnostic indications concerning VTA1 & VTA2 the entire throttle body assembly is replaced (includes throttle valve, throttle valve drive servomotor and both hall effect sensors).

    A bit of a puzzle to me is that a new accelerator pedal, FULLY released, can have a VPA signal below (0.5 volts) the useable level (0.8 volts) or above (1.1 volts) the useable level and still be acceptable.

    Obviously a pedal assembly with a fully released value of 0.5 volts would exhibit some travel slack/backlash as it's being depressed before it reaches the 0.8 volt "useable" point.

    A puzzle.
  • billranbillran Member Posts: 113
    Not that it matters but I am an Engineer myself, albeit not an Automotive Engineer. I have to wonder what exactly the expected outcome of this discussion really is? Obviously, the Toyota Engineers would be the ones best suited to figure out why a very small percentage of owners report the hesitation. They apparently looked into it and issued a TSB which has been reported as very successful by many people.

    So, all that remains to be solved is why do a very few owners still report some hesitation after the TSB? At that point it would seem like you are certainly looking at a characteristic that applies to so few vehicles that the type of across the board theorizing you are doing here would not really apply.

    It seems to me like most of this discussion generally ignores that fact that very few owners even report any hesitation, and that a TSB exists that fixes the problem for many.
  • wwestwwest Member Posts: 10,706
    Are you really saying that automotive problems shouldn't be addressed unless LARGE numbers of drivers complain?

    IMMHO the really GOOD engineers are born problem solvers, will totally immerse themselves in a seemingly unsolvable problem.
  • alan_salan_s Member Posts: 362
    Could someone clarify please...
    I called my Toyota dealer last week and also opened a case with Toyota Customer Relations in CA over the transmission issue. Both the dealer and Toyota say that no TSB exists for the Avalon transmission and Toyota are "not aware of any other concerns regarding the Avalon transmission."

    Does TC004-05 ECM CALIBRATION: SHIFT FEELING ENHANCEMENT 2005-06-03 apply to the 05/06 Avalon?
    Someone suggested TC002-03 in the Avalon forum but nobody seems to know about that one either. The NHTSB and ALLDATA sites don't list either of these TSB's.
    If anyone has been successful, I'd appreciate the name of a dealer anywhere in the US or Canada who is aware of the TSB and has applied the TSB. I'll call them wherever they are.

    Thanks, all.
  • billranbillran Member Posts: 113
    wwest, not at all. But the fact that very few owners even report any hesitation, and that a TSB exists that fixes the problem for many, is a very important part of the equation.

    These are very relevant and important factors that for some reason seem to be consistently overlooked/ignored.

    I drive one of these vehicles everyday and it performs flawlessly. I would say that the vast majority of other owners who are not reporting any hesitation are experiencing the same excellent performance.
  • alan_salan_s Member Posts: 362
    billran you are indeed fortunate that your car does not have this problem. Mine is so irritating and unpredictable to drive in traffic, I'm to the point of dumping it.
  • billranbillran Member Posts: 113
    alan, I am sorry to hear that. I am not sure if there is a TSB for the Avalon or not. I did a quick search and did not see one right off the bat. I would think if that car had the same issue, and a similar cause, that one would be issued.
  • wwestwwest Member Posts: 10,706
    Not the way equations work in my world. When trouble-shooting any problem the very first thing you do is remove, subtract out, any non-pertinent information.

    Do millions of drivers not have this problem?


    Does the TSB adequately address the problem for some?


    Does any of above tell us anything about the few that are still having the problem, some of those even having had the TSB applied?

    Not that I can tell....

    So, what parts of the "equation" do you think we should continue to address?

    IMMHO what's needed is to look into what anomalies exist, vehicular or personal, within the relatively small group still experiencing the problem.

    And having an accelerator pedal with a fully released voltage output that is always above 0.8 volts, up to 1.1 volts, purely by happenstance, might be the sole causative factor.

    That might make it look like the gas pedal is never fully released, always slightly depressed, as might someone who has a habit of left foot braking.

    Suppose, in these few cases, the engine/transaxle ECU "thinks" you are braking with your left foot when you're really not.

    What might the ECU do in the case of an actual left foot braker?

    It certainly would not, might not, allow the engine to develop any serious level of torque with the brake applied. But no, we know that isn't happening, too many people driving merrily down the road, cruising along, with the brake lights shining brightly.
  • grandaddygrandaddy Member Posts: 66
    Put an end to this ridiculous, contrived topic rather than encouraging any more discussion.
  • billranbillran Member Posts: 113
    Fair enough. Whether the points I mentioned are factored in or factored out, the result is the same. I would still have to wonder though. Without a car that consistently displays the phenomena to test the theories on, this discussion will just spin on for eternity with no practical result.

    Hey Grandaddy, what happened to that post you put here yesterday, I rather enjoyed that. And I think you hit close to the mark. You have to be careful how you word your posts though, sensitivities run high.
  • user777user777 Member Posts: 3,341
    well then now you are on to something man.

    it's possible the link i posted to ECU and TCM functionality, specifically TPS is older and relates to the 4-speed transmission era technology. the TPS was clearly a variable resistor, and the IDL sensor a physical switch. you're saying the newer systems use hall effect transducers? i have no reason to doubt you.

    look folks, we are at a disadvantage here not being Toyota Design Engineers with access to supplier information and details of the implementation.

    the puzzle WWEST is dealing with at the moment is how can a calibrated transducer (in this case the accelerator, not the throttle position sensor) have a return to zero value that is very discrepant from nominal and still usable by the control system?

    the problem people are reporting is comming off the accelerator (Throttle closed), then re-applying the throttle with a delayed response.

    this slop or non-linearity and how it may be treated in SW can very well be at root cause.

    like I said a few times before, someone with a really problematic car should be pushing to have first their TPS and Throttle Body replaced, and then their Accelerator Pedal assembly. this most recent post by WWEST might suggest the reverse order of replacement.

    in my opinion there *IS* more your service manager can do for you!
  • wwestwwest Member Posts: 10,706


    User777 and the Boeing 777 is the first with DBW...

    Any correlation?

    In any case the information in #239 above was taken directly from the 2004 Repair Manual for the RX330, Pub No. RM1027U1 Volume 1.

    Throttle Valve position sensing page 05-93 to 05-103
    Accelerator Pedal position sensing pages 05-249 to 05-261

    To continue....

    When I had my 2000 GS300 the engine surge at throttle tip-in (actually accelerator pedal tip-in, initial slight application/depression) would oftentimes result in wheelspin, especially on my gravel driveway at home. Even absent the wheelspin, on dry pavement, I was never able to learn to feather the gas pedal at tip-in lightly enough to avoid an initial acceleration surge consistently.

    I initially assumed the throttle linkage had too much backlash, too much slack in the mechanical connection from the gas pedal to the throttle valve. I adjusted out all of the cable slack I could but yet the problem persisted.

    So I went in to Lexus of Bellevue to explain the problem and see if there was a fix available. I gave up after the service manager spent so much time trying to convince me that my 2000 GS300 was DBW and therefore mechanical coupling slack/backlash could not possibly have been, be, the problem.

    Just how does the DBW system decide how or when the accelerator pedal is fully released? Obviously that is something it "learns" during that initial 15 second period after a new one is installed and the engine is started.

    If the "learned" voltage at that time is below the useable range, intentional, designed in "slack" then all is well. But what if, by sheer happenstance, a definite minority of accelerator pedal assemblies come from the factory with a fully released VPA sensor voltage above the explicit, 0.8 volts, "useable" voltage?

    Lets jump over to the throttle valve for just a moment. The throttle valve assembly comes from the factory with an explicit "throttle valve fully closed" VTA1 sensor voltage, 0.69 volts. 0.93 volts is the explicit VTA1 voltage for 6 degrees o throttle valve opening, likely the idle position.

    So the validity of the throttle valve fully closed signal can be readily checked, on the vehicle, in the field, embedded in the firmware, by simply driving the throttle valve servomotor toward the fully closed position. Basically trying to drive it beyond the fully closed position. If the resulting sensor output signal is something other than 0.69 volts (+/- and RCH) then the throttle valve assembly has malfunctioned.

    I can easily see how the accelerator pedal fully released position is "learned" during that 15 seconds even if it happens to be above the "useable" 0.8 voltage level. But what if another aspect of the engine/transaxle ECU firmware still thinks the higher voltage means the accelerator is still depressed, but only at certain specific times or unique driver actions?

    Page 05-250 has a chart showing, labelled, "Usable Range". The chart/graph indicates that the VPA usable range starts EXPLICITLY at 0.8 volts and ends at 3.55 volts plus or minus 0.95 volts. Obviously the VPA signal voltage can drop below 0.8 volts and as a designer that would be acceptable to me, even desirable to be sure I never opened the throttle valve when the gas pedal wasn't depressed.

    What doesn't make sense to me is the acceptable VPA output voltage tolerance level of 0.5 volts to 1.1 volts for a fully released accelerator pedal. That means that a fully released accelerator pedal's VPA sensor output voltage can be as high as 0.3 volts above the bottom end of the usable range and still function correctly.
  • user777user777 Member Posts: 3,341
    If you can regularly experience the hesitation when slowing, then getting on the gas with your vehicle, either in stop and go, getting on a ramp after applying the brake, or slowing in the median to prepare for a left turn while waiting for an opening in traffic, and getting on the gas, would you try this simple experiment?

    In the morning before you drive, put both feet firmly on the floor mat so as to not touch the brake or the accelerator pedal. Turn your ignition key to the "ON" position but resist the urge to turn it all the way to START. Wait about 10 or 15 seconds for the fuel pump to establish fuel pressure.

    Then with both feet still on the floor mat, turn the key to start, but do not give the vehicle any additional gas!

    Providing the car starts and keeps running (it should), wait an additional 20-30 seconds before putting your foot on the brake and taking it out of Park.

    Now, put the vehicle in gear and drive as you normally drive and try the scenario underwhich you typically experience the hesitation.

    Please report back your results (worse, better, no change) and the scenario where you experience (experienced) the hesitation:

    Also take note if your general shifting has changed if at all.

  • wwestwwest Member Posts: 10,706
    I went back and reviewed bkinblk's trial with disconnecting the battery each day. It appears that disconnecting the battery definitely helped alleviate the problem, at least in the short term.

    I think what this may mean is that the parameter causing, or contributing heavily to the problem, is not driver unique alone.
  • user777user777 Member Posts: 3,341
    disco on the battery probably wipes the mapping or learned driving behaviors in addition to other sensor data that has to be built up again over time. Thus the ECM/TCM may revert to defaults.
  • wwestwwest Member Posts: 10,706
    Driver charactoristics, unique or otherwise, are erased from ECU memory the instant you turn the ignition key off. Each time you start the vehicle in motion the ECU begins the "re-learning" process regarding driver charactoristics. Within 60 seconds you have been "binned" into one of four driving "styles". By the time 3 minutes have elapsed you have been further refined into 1 of 16 "styles". Thereafter the ECU(s) keep a running record of not more than the previous three minutes and will revise your style on the fly as it becomes necessary.

    The above is taken from an SAE white paper I found on the internet quite some time ago and I don't remember if it was unique to any specific marque or not.

    But I think you will agree that none of the driver unique "learned" memory aspects can be carried over to the "next" driver.

    Otherwise my wife might find driving our Lexus somewhat discomforting after my weeks of slinging it around curves again and again.
  • wwestwwest Member Posts: 10,706
    Okay, how do we know that there are not two "forms" of engine/transaxle delay/hesitation? One form which Toyota has deemed "normal", to protect the drive train, and a second, extended one, causing delays of one of two seconds are more.

    I can fully and easily accept Toyota' explanation that there is an intentional delay in allowing the engine to develop a substantial level of torque as the downshift is completing. I often drive a stick shift and I do not wish to be replacing the clutch prematurely. So I am careful to not apply gas inordinately quickly as I engage the clutch after a downshift.

    So I can fully accept Toyota explanation that the delay is to protect the drive train. But just how long a delay are they talking about? Certainly one that would be noticeable if one were in an especial hurry to accelerate.

    But clearly, that wouldn't be 1 to 2 seconds as is being complained about, a few hundred milliseconds, maybe.

    So, ALL of Toyota's electronically controlled transmissions with DBW are exhibiting some level of downshift delay. Enough of a delay that any driver having experience with previous, non-DBW transmissions, will definitely notice when quickly returning to acceleration circumstances.

    So, what if the anomalous "extended" delay only occurs on vehicles with Trac, or even VSC.

    Look at the contention between the parties, posters, involved, some say the delay is hazardous. In my opinion a 1 to 2 second unpredictable delay might very well put one into an unsafe condition. But many who claim to be experiencing the delay contend "no way" to the unsafe or hazard issue, and often further dispute the 1 or 2 second amount.

    Good, logical evidence that there may be two forms of the delay/hesitation.
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