"...that there are at least 100,000 occurrences on the internet where someone has misspelled steering as you did."
Bingo. Just because it's on the web or returns hits in Google doesn't make it right.
Back on topic, the number of instances of hesitation/delayed downshift imply a design flaw (probably software as wwest opines) rather than a sensor quality issue or malfunction. I'm sure the PPM on sensors is in the single digits if measureable at all. I'm also convinced that driving habits and driver sensitivity play a part. My wife has never once complained about her Highlander and she drives it a lot more than I do.
From the documents it is pretty clear that the (down)shift sequence is different if you simply release the gas pedal vs releasing the gas pedal AND subsequently stepping on the brake pedal. For instance stepping on the brake pedal will ALWAYS result in releasing the torque converter's lockup clutch.
Then there's the question of back and forth gas/brake activity in some of these circumstances.
Gentlemen Please ! We are on an exciting quest for knowledge. Let us stay focused on what we know about transmissions, and on how we can remove the unknowns. The discussion about VSC is important. There is an AVALON forum entry about the car braking erratically, and one response comment was that perhaps the VSC was attempting to take corrective action in behalf of the safety of the driver. If the VSC algorithms are given bogus sensor information, then, it can think that the car is going around a tight curve, when , in fact, it is going straight ahead. The VSC could elect to use braking on specific wheels to correct the "virtual" turn. Is this possible ? If so, I think I am glad that my cars do not have VSC. In my line of work, 75% of the software development has to address the error handling and all the non-normal situations. For example, what if sensor # 1 does not report in a timely fashion ??? What it you get an illogically high reading from sensor # 2 ??? These are real issues in the oil production and refining industry. We have to develop our logic to fail in a "safe" way.
However, in the case of VSC, which is in itself a safety system, I wonder how much validation it applies to the inputs that feed the VSC algorithms. I get gray hair thinking about this situation. Since VSC could affect brakes, engine, transmission, etc, I sincerely hope Toyota had their "top-guns" doing the programming and quality assurance.
ok - we'll get shot for discussing VSC in a transaxle/shift delay forum for sure while we waste bandwidth on steer vs. stear (wwest - probably the written english language will continually devolve until your variant is accepted), but here - what the hey:
>>on soapbox: you're bringing up an important point about safety systems, i believe i remember reading two posts over the last year, one regarding a sienna that had a bad yaw or steering angle sensor where brakes modulated and put the vehicle in the oncomming lane...sensor had to be replaced, and another on an odyssey where a failed sensor caused the brakes to be engaged and slowed the vehicle in traffic. i might have the particulars a tad inaccurate. however the point is i believe these stability systems are actually going to be mandated in the future, and we have to be vigilant about the thoroughness of their design, implementation and test.
when we get in an unsafe scenario and the technology is working as designed, i'm confident they may be the difference between a scare and injury or death.
but, if they fail - depending upon the situation, we might be at risk.
i work in an industrial controls engineering capacity as well and i'm right with you bettersafe. as much as i think VSC will be a differentiator and life saver in some scenarios, i'm going to be a late adopter of that technology because of its complexity and it's costly fix if it fails, the possibility they will be repaired improperly, but also... today, i just don't trust the engineers to have tested all possible scenarios, sub-system interactions, failure modes, and confounding human response to degraded or conflicting indication or operation. just my opinion folks.
factually, engineers are not all versed in study of human factors in complex systems. the aviation controls industry has experience with this topic. this is why i have stated before, it's only a matter of time before the human factors community locks on the automotive industry.
human factors what they are, no matter what status or alerting systems we put in place to aid the operator, humans will ignore them, or possibly mis-interpret them... even go so far as to disable them (people pulling the fuses or indicator lamp on the Check Engine Light)...so even if we do our best to design a system that is robust, "silent unless certain", and failsafe, we also must consider the human element of the equation. let's also consider greed (gread for you wwest), and how some repair shops have been caught replacing deployed airbags with bad equipment or nothing but newspaper behind a airbag cover.
sometimes good designs go bad because of how the operator will react in different scenarios was not fully considered. same is true w.r.t. how the systems are maintained by others.
how do we know then when these systems are operating properly? for example, do we find out rather late when we are being put into another lane, or slowing in heavy traffic, or do we have telltale signs which we mis-interpret like perhaps experiencing retarded engine output, delayed or hard shifting?
If you knew how many engineers and programmers are involved in bringing an ABS/TCS/ESC system to market, you would not feel like you had to be a "late adopter" of this technology. Failures are more likely to be mechanical in nature (like the recent GM tone wheel corrosion issue) rather than software related.
I have yet to read a report of a ESC failure resulting in accident or injury (keeping in mind that even ESC can't change the laws of physics). OTOH, I'm certain that ESC systems have already saved many lives.
The only written complaints I've read about ESC (not counting any rants and raves by Edmunds' forum visitors) , are those of the car mag cowboys complaining about the electronic nannies, mainly in Toyota/Lexus systems. I say let ESC keep me and most drivers out of trouble, even if it means I can't pull .9g on a longer sweeping curve.
There is an AVALON forum entry about the car braking erratically, and one response comment was that perhaps the VSC was attempting to take corrective action in behalf of the safety of the driver. I also wonder about that Avalon discussion where the car "went out of control" after a panic stop to avoid a rear ender. Could that have resulted from simultanious application of brake and accellerator? (This was a Panic stop situation) Or perhaps the car behind didn't get stopped in time and "ticked" a rear bumper--just enough to start things going south? The owner talked about 65 MPH speeds,bumper to bumper, on a two lane causeway, rush hour...... VSC may not have been a factor in such a situation--there isn't much room for error in the conditions described. It could also be argued that VSC may have worked by preventing a much worse situation, spin, rollover.... What do you think?
I cannot seem to find the one on the Odyssey. It might have been Accord, or Pilot. Apologies.
If you knew how many engineers and programmers are involved in bringing an ABS/TCS/ESC system to market, you would not feel like you had to be a "late adopter" of this technology. Failures are more likely to be mechanical in nature (like the recent GM tone wheel corrosion issue) rather than software related
mechanical issues... right forgot those. throwing many engineers at a system design doesn't bring me more comfort. if anything - less.
possibly being the cause of a deadly accident, how would anyone, law enforcement, accident investigator, etc, ever know, discover, that a VSC failure was the root cause of the accident.
I note that the yaw sensor on my 2001 is located on the outside of the body, above the rear axle, subject to damage by road debris, etc. By 2004 it had been relocated inside under the carpet near the door.
Evolution...
I think the current design of ABS is significantly flawed, it should never activate until VSC indicates that the vehicle is not following the "line" desired by the driver. But, who am I to criticize?
Two many cooks.....
There are those that think the Itanium processor went awry, and is now a failure in the marketplace, because the design group became too large with the HP and Intel group fighting over design superpremacy. The HP team won(???).
Any keep in mind that the engine/transaxle ECU module in all likihood contains more than one microprocessor. Cross communication between these processor to attain a common goal can be a design nightmare.
One more question about VSC. I recognize that control modules or sensors could malfunction. Rare, but possible. Do you believe the condition you're concerned about, namely differential braking, would be sufficiently strong enough to overcome or even restrict an attempt to correct by the driver? Personally, I don't think so. Everything I've read re that possibility says no; braking pressures in those conditions aren't severe enough.
I am aware that controle modules can fail. I said that. You must also admit that such failures are few and far between. The question I asked had to do with VSC control module malfunction (paraphrasing): "Would the resultant differential braking be more that a normal driver could easily overcome by simply steering the vehicle". I agree, a degree of automation would be present under those circumstances, but could it seriously affect a driver's ability to deal with it? Same question applies to the engine hesitation issue.
PS. There's a very good book you might be interested in reading. It's called "A Theory Of Cognitive Dissonance". If you get a chance, look it up.
There are actually several answers to that question.
At the 24 Hours of Daytona, two weeks ago, car #86, a new Porsche 997 GT3 hit the wall on lap #17 at the "bus stop" with the top team driver, 10 years at the "24", at the wheel. He isn't/wasn't sure what happened but concluded that is/was likely the brakes locked up. Personally, knowing not much about the non-ABS brake system on the Porsche GT3, I think it much more likely that rather than a front brake locking up one of the floating calipers didn't float and the brake on that side simply didn't work.
Same result however, differential braking at the front at high speed.
Second answer has to do with driver reaction. What would the majority of drivers do in this instance having NEVER encountered the circumstance before?
Suppose the driver was already on the brakes at the time of the incident? In that instance wouldn't most of us simply apply more pressure to the brake pedal? Thereby exacerbating the problem?
Absent a firm grip on the stearing wheel at the instance of differential braking the steering wheel might just slip through one's fingers due to the feedback from differential braking.
We might take note at this time that VSC activation feedback is now being provided in much the same way a stick-shaker works in a commercial airliner to warn pilots of an impending stall.
On vehicles with electric power stearing it is now harder, actual resistance, to turn the stearing wheel in a direction that would exacerbate an overstearing condition that VSC is already working to alleviate.
But keep in mind that the circumstances wherein VSC might inadvertantly, falsely, apply differential braking to your detriment would only be on a RWD vehicle during an over-stearing event.
And that's not the subject of this discussion, at least from my viewpoint. My theories are concentrated on FWD vehicles exhibiting engine/transaxle delay/hesitation.
CLARIFICATION...
I'm not actually proposing that this is a full and complete activation of all aspects of the VSC system. Only pointing out the possibility that a flawed VSC firmware design, and a resultant failure, might be the root cause of these engine/transaxle hesitation complaints.
I think everyone will agree that of the two "events" VSC is responsible to help overcome, understearing and/or overstearing, FWD vehicles will generally be much more susceptible to understearing/plowing.
Understearing is most easily described as a circumstance wherein the driver is trying to turn the vehicle while underway. The front wheels are not aligned with the vehicle longitudinally, but the vehicle is not following, partially or fully, the "line", direction, set by that angle.
In other words the front tires have insufficient roadbed traction. That might be the result of engine driving torque or engine compression braking or it might be due to speed and vehicle inertia or even both.
So, what to do?
First, slow the vehicle.
The front tires have already exceeded their traction coefficient so any braking that would help will only be at the rear. And that's exactly what my 2001 AWD RX300's VSC system does in this instance, it applies braking to both rear wheels.
Second, remove any possibly for engine torque, leading or lagging, from interfering with the requirement for additional lateral traction. My 2001, not having DBW, starves the engine of fuel in this instance.
So the VSC system "disconnects" the gas pedal from the throttle valve while simultaneously "telling" the engine/transaxle ECU to belay any pending downshifts.
for people interested in or practicing engineering with a focus on human factors in complex systems (bettersafe) here are a few books i'd recommend: Psychology of Everyday Things (or it's retitled equivalent: Design of Everyday Things) Set Phasers on Stun: And Other True Tales of Design, Technology, and Human Error Automation and Human Performance: Theory and Applications (Human Factors in Transportation) Designing for Situation Awareness
i think for the general public, the set phasers on stun book will be potentially an eye opener (and the easiest of the above to read), specially for those that blindly trust technology.
by the way, i would NOT agree control modules rarely fail.
Hopefully someone with a misbehaving vehicle will get to a mechanic with the proper OBD hardware, software and experience. . . . and we can get some hard information. I feel we have a long long list of possibilities, lots of good hypotheses, but not a lot of hard evidence.
To Wwest. Thanks for the reply. Your hypothetical examples have some merit. No further questions. I also agree there's been enough off topic discussion re VSC systems, so I won't belabor the issue further, except to say two things....., First,I wonder how many injuries (or worse) have been avoided by such systems; Second, We'd better get used to having them around because our Legislators are serious about making them mandatory for all vehicles.
To User777: Thanks also for your reply. Your sentiments about technology aren't shared by everyone, but they're your sentiments and you're certainly entitled to them. I also suggest neither one of us can speak authoritatively re Control Module failure rates, except to say that blanket condemnations of all such systems is a flawed approach to solving problems. IMO, by far the biggest "design flaw" in this entire discussion is the HFF (Human Failings Factor). Far more often than not, We are the authors of our own misfortunes--especially when it relates to automobiles.
I think what Bettersafe says sums it all up:"...... a long long list of possibilities, lots of good hypotheses, but not a lot of hard evidence"
may i suggest this hylyner: instead of reframing comments or opinions expressed by others, why not just clearly state your own? you're articulate and entitled to your perspective - but reframing the posts of others isn't really appropos.
my comment was to the point you made regarding your presumption that i'd agree the failure of these modules was rare.
My opinion? I agree completely with what Bettersafe says and repeated it. Besides, it's the truth, I've said as much previously, and in this instance it was said far better than I could. This hesitation issue is an great discussion, but well and truly long on hypotheses and short on hard evidence. If it's a genuinely sincere objective to find solutions, a great deal more work needs to be done in the area of fact finding. (Emphasis on "Genuinely Sincere")
One more observation, for the good of all. Telling others what's appropos or otherwise re their posts is best left to the Host.
"This hesitation issue is a great discussion, but well and truly long on hypotheses and short on hard evidence."
Ain't that the truth. Just like the previous forum on hesitation that was closed due to constant bickering, this one has just about run its course, imo.
My prediction is that the issue will never be fully resolved, if for no other reason than the whole concept of delayed downshift/hesitation has an air of subjectivity about it. The most frustrating aspect of the discussion is wwest's refusal to acknowledge the correct spelling for steering
Hey, at least give poor Wwest credit for stearing the discussion back on track! (Geez, now I'm doing it!!) :surprise:
As regards what you said in the last paragraph--Yeah, you're probably right, it'll never get resolved. Definitely too much subjectivity. Perhaps too much bias towards a 'cause of convenience' as well. It's next to impossible to resolve complex problems by working backwards from a single predetermined cause. However, this discussion does have value, in that some excellent technical information flows from it.
This discussion is far from running its course. I was enjoying the technical discussions and feeling that things were on a very good track. Keep it up, wwest, user777, and bettersafe! I have been in a learning-mode, since I am not technical enough to add to the discussion. I think I would also enjoy the books you recommended, user777, but will stick to the one you recommend for us laymen.
As long as this problem exists and a solution has not been found, the forum is needed. New ideas and new perspectives on the problem will likely continue to come in and be analyzed until it is resolved. That is what it is for and it is why this discussion forum was formed, where it won't interfere with other discussions taking place on the specific model forums.
You write beauty to my ears. I bought a 02 Avalon new and haven't had any problems with the VSC. Why. Cause there isn't any.....IMO, the car buying public, not the industry itself ofcourse, would be better served to put in better componetry in their suspension and brake systems. Driver's would do better taking advanced driving techniques, and avoidance manuevers, emergency braking, etc. on their own vehicles. Then you could skip ALL the electronic gizmos and wouldn't have to pay for their upfront cost and repair costs.
We have an 03 ES and an 05 ES. Neither has VSC; both exhibit hesitation in some situations. However, we also have an 03 Mercedes E320 with electronic stability control (ESP in Mercedes marketing speak). I drove that car out to ski areas in Colorado in winter (with winter tires fitted) and the car performed amazingly well. I have experienced fishtailing and spin outs in rear wheel drive cars (not fitted with ESC) in winter. Though there may be cases that electronic stability control (ESC) may fail and the fail safe may fail and cause injury or death, I would argue that the benefits of ESC (especially in rear wheel drive cars) GREATLY outweighs the risks. This is borne out in that I believe that their have been studies reporting that although ABS has no measurable statistical safety benefit, ESC does show a safety benefit. If your standard is absolute perfection, then you miss out on the benefits. Example: you would stop taking all medication regardless of benefits because all medication has risks. So to wwest who is a Porsche fan, I would HIGHLY recommend PSM (the Porsche version of ESC) and 4 winter tires for any rear wheel drive Posrche if driven in winter conditions. I would also highly recommend ESC for any high center of gravity vehicle (SUV/Pickup/Minivan) to reduce the risk of rollover.
"Drivers would do better taking advanced driving techniques, and avoidance maneuvers, emergency braking, etc. on their own vehicles"
You surely got that right!! I tried to say as much in my post 170, above. You said it better. The weakest link in this entire controversy is the "Human Failing Factor". We ourselves are the "design flaw" smack in the center of this issue. Like Pogo said "We've seen the enemy and the enemy is us". In spite of more and more safety devices carmakers develop, drivers seem to find even more ways to negate their effectiveness and just keep on hurting themselves. Personally, I would support mandatory driver training involving all your suggested techniques--and more! Add to that mandatory driver's licence recertification--with the same training--every 5 years!
on that line of discussion we meet on common ground. train to know your capability, the capability of your car, and to be more aware of the situations in which you find yourself behind the wheel. actively work to stay clearly engaged in the driving task and well within the dimensions of all of those extents.
some of this technology has high utility, but is also a marketer's dream come true.
My 2001 Porsche has PSM and is a C4. PSM is not a good example to compare with VSC as PSM delays any immediate corrective action to give the driver the first opportunity. With four trips around the track at Daytona I only "wagged" the tail once and apparently due to my quick counter-stear inputs PSM didn't activate.
The PSM is a really good feature, as is VSC, since none of us can be completely "on our toes" 100% of the time.
I would to as long as it involved stationary driving simulators (as in flight simulators) wherein the driver could be put in DIRE circumstances, absent dire results, and thereby learn how to react properly.
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". You would not typically engage the clutch with a stick shift before moving the shifter into the "gate", selected gear position. Toyota's automatic gearbox is now preventing the engine from developing torque until the transmission's internal clutches for the selected gear ratio are fully and firmly seated.
This post does not concern, does not propose to address, the "standard" transmission shifting delay as disclosed by Toyota.
A relatively small number of Toyota and Lexus owners, encompassing model years 2002 through 2006, are complaining about extensive downshift delays. These complaints seem to primarily involve FWD vehicles or AWD vehicles with definite front torque biasing and 5-speed transaxles.
This post will focus on just what those few owners might be doing, or not doing, during the operation of the vehicle that might lead to an extended downshift delay period of 1 to 2 seconds.
Technology, ain't it wonderful?
BA, Brake Assist: Just what is this?
Apparently via studies by the automotive industry at large it was learned that some of us are not using out brakes correctly, at least not in all instances. As I understand the implementation, design, in an emergency or panic braking circumstances some drivers apply the brakes quickly, but for some unknown, unknowable, reason then just as quickly slack off the pedal. This might be due to reacting to, being unfamiliar with, the resulting pulsations from ABS activation, or it might be a "learned" reaction. Before the advent of ABS many drivers "learned" that severe, hard, brake application would often result in loss of vehicle control.
So the industry decided, on its own, that many of us would be better served if "they" did the "driving", at least in this instance.
Basically BA "watches" the rate at which we apply pressure to the brake pedal. If the brake pedal "stroke is rapid/quick but then brake pressure slacks off quickly then the BA function is activated and HOLDS the brakes into a heavy application for some predetermined period even with teh driver having slightly back off of the brake pedal pressure.
I may be somewhat wrong about BA in the above dissertation by the important point, aspect, is that BA is being triggered by the "rate of brake pedal travel/activation".
Porsche 997 EBD, Extended Brake Assist:
Same as above but with one added feature.
The processor "watches" the rate at which the accelerator pedal is released. If you lift the accelerator pedal rapidly then the system presumes (second guesses??), that your foot is now headed for the brake pedal and "pre-charges" the brake fluid pressure to move the brake pads from their otherwise retracted position and into "slight" contact with the rotors.
So, we now know that the Toyota/Lexus BA, Brake Assist, system is watching the brake pedal rate of travel to determine if brake is assist should be activated. And we also know that Porsche is watching the rate at which foot pressure on the accelerator pedal is removed.
So, given the above as factual, is it really so outlandish to think that the Toyota/Lexus drivers who are experiencing these extended downshift delays aren't somehow, in some fashion, causing these results?
I can tell you truthfully and frankly that my 2001 AWD RX300, when I'm trying to stop on a very slippery roadbed surface just plain does not want to come to a full and complete stop. The anti-lock braking system goes absolutely bonkers! The slower the vehicle speed declines in this circumstance the "busier" the anti-lock systems becomes.
But frankly, that's exactly the way it should operate, allowing me to maintain directional control right down to the lowest IPS (inch per second) travel rate. But what would happen if I suddenly slipped the transaxle into 1st gear? The idle engine speed would likely provide enough engine compression braking to overcome the ABS activity.
And that latter is exactly one of the aspects VSC protects you from.
If VSC detects understearing on a FWD vehicle it will quickly act to alleviate engine driving torque and prevent engine compression braking.
Why would rapid release of the accelerator pedal, or rapid release of the accelerator pedal and then quick application of the brake pedal "falsely" trigger a VSC activation? Or for that matter since the ECU in which VSC functionality is embedded is the "Skid Control ECU" and therefore handles all of the brake control functions, ABS/BA/Trac/VSC/EBD, might not a false activation of any of these functions be the cause?
Porsche is assuming that rapid release of the accelerator is a likely indication of quick subsequent brake use.
What if we follow that tract and see where it goes?
We already know that at extremely low speeds on a slippery roadbed engine compression braking can overcome the ability of ABS to keep the front wheels rolling. So suppose Toyota is preventing shift-downs and/or maybe even commanding upshifts in the same circumstances and for the same reasons. Porsche is precharging the brake pistons?
Just a couple of side issues.
Between 2001 and 2004 Toyota moved the two VSC sensors, stearing wheel position sensor and yaw sensor, from a direct connection to the skid control ECU to connection via CAN, Controller Area Network. In 2001 all network communications was via the proprietary BEAN, Body Electronic Area Network.
That might mean that Toyota (or Denso) is no longer in control of the VSC functionality. Bosch, maybe?
When I traded in my 2000 AWD RX300 for the 2001 AWD RX300 I did so primarily to get VSC and HID. I was told at the time that a new feature of trac was to provide a virtual form of front and rear LSD, Limited Slip Differential. I remembering wondering at the time that if that was so, brake apportioning being used as a front and rear LSD, then why hadn't they just gone ahead and eliminated the VC, viscous clutch, and used brake apportioning for virtual LSD implementation for the center differential?
That did!
Over the intervening years and the 50,000 miles driven I have come to the firm belief that the brakes are being used to apportion torque front to rear. Very early on I discovered that the VC was almost always "flaccid", almost never stiffened up enough to couple any significant level of engine torque to the rear. On a 4 wheel dyno it took 20 to 30 seconds before the VC stiffened enough to provide ~25% of the engine torque to the rear driveline.
All that is my way of saying, proposing, that there are, may be, implementation aspects of the RX330 engine/transaxle ECU and skid control ECU that are not advertised/published.
Just this morning I asked the service manager at Bellevue Lexus if the there was a method for disabling VSC. His immediate response was "pu
Just this morning I asked the service manager at Bellevue Lexus if the there was a method for disabling VSC. His immediate response was "publically available??". And then went on to explain that the one published (disclosed) in AutoWeek worked.
And even after I learned of the existance of several of the unpublished C-best options available for my 2001 RX300 the dealer denied their existance until I cam back with a printed copy.
So, what if a portion of the Trac firmware is "watching" the rate at which you release the accelerator pedal and, like Porsche, is somehow preparing the system for a subsequent brake application?
How many of you, given a stick shift on a FWD vehicle, would use engine braking to slow the vehicle if you weren't certain of a high level of roadbed traction? And what about downshifting a FWD vehicle for slowing?
What, no volunteers??
No insanity out there, none?
What if that is exactly what is happening with the owners that are experiencing the extended downshift delay? The Trac system is not allowing downshifts if it expects a quick, following, brake application.
"I may be somewhat wrong about BA in the above dissertation by the important point, aspect, is that BA is being triggered by the "rate of brake pedal travel/activation"."
What brake assist does is apply the brakes faster than the driver can if it senses a panic stop. It essentially changes the gain of the brake booster so one reaches maximum attainable brake line pressure quicker. Mainly a benefit to smaller and/or older drivers who don't have the strength or the reaction time to achieve maximum decel in a panic situation.
And who, if not the manufacturers, should decide what new safety features should be added?
Wwest, I'm wondering if something said in your post could be misunderstood: "Toyota has now publicly announced, admitted, that there is now an inherent delay in downshifting their electronically controlled transmissions and transaxles to "protect the drive train". I may be wrong but it's my understanding this "public announcement...admission" statement stems from unverified remarks by one poster in the now closed Engine Hesitation forum. The poster was alledgedly told this by a Toyota Service Rep during an arbitration. Technically, if verified, that story might qualify as a "public announcement" (ie out in public), but anecdotal or hearsay remarks in Edmunds forums certainly aren't in the same category as official and widespread information sources. To clear up any misunderstanding, do you know of any links pointing to a more official source, such as Toyota Corporate?
I had a long chat with the service manager at Bellevue Lexus yesterday and while I can't say he made an admission he made no attempt at any time to deny, in any way, that the problem had been around since 2002 and remains a problem to this day.
And as was discussed previously I consider the availability of the TSB as equivalent to a public announcement/admission.
Also note that there are really two "admissions" of concern here. The standard one to protect the drive train which everyone is subject too and likely as un-noticeable, mostly, as the up-shifts in my 2001. And then there is the "extended" one the TSB attempts to solve.
Thank you for your response and candidness. I certainly don't wish to take issue with your opinions on the matter. However,your response does validate my thought that there's not really an official source " publicly announcing...admitting...hesitation is designed in...to protect the drive line" I realize and appreciate that hesitation is a contentious issue with you and some others. I just don't think it's helpful to have potentially misleading statements out there without some form of explanation with them to frame things in proper context.
There are two million cars on the road with the drivetrain in question.
Multiple searches have failed to identify enough complaints to amount to even one tenth of one percent of those cars. In fact, at best maybe 40 complaints for any specific model can be located, and many of those are obvious duplicate posts by the same people.
There are those here who, for whatever reason, want to portray this as a huge issue. The facts just don't support that.
Some say they can duplicate the problem in any vehicle, yet there are two million owners who dont report any problem at all. I am one of them, and I know two others personally.
Okay, we know, factually, that millions of Ford vehicles with cruise controls have a flaw in the brake light switch that is actuated by brake fluid pressure. Over time the fluid penetrates the switch and comes into contact with a SOLID, non-fused, 12 volt battery source and that often results in a serious FIRE.
So, what is the ratio of these admittedly flawed vehicles out in the public's hands versus the number of complaints or forum posts regarding same.
Wwest, I'm sorry, but comparing the Ford brake light issue with this one is VERY thin logic. The two issues are completely different, and I'm surprised that someone as astute as you seem to be would even suggest it. Did you really mean to infer this issue is lurking just below the surface in all two million or so vehicles in question? Oh, and add to that, it's going to eventually emerge as a serious threat to everyone's life and limb at some time in the future? Come on now!!! :sick: I certainly hope that wasn't your intention, because it would be irresponsible or worse--and you don't seem to be the irresponsible type. Billran is right. There are over a couple of million of them out there, and darn few complaints. The 50 or so here won't even register on the stat scale!! Not only that, but it's fixable. As you and others keep reminding us, there's a TSB for that purpose!! Furthermore, in the case of your Ford example, the NHTSA ordered a massive recall---not to mention a few devastating fires, multi million dollar liability actions, etc. That isn't even on the radar in this hesitation issue. As Billran also said, if one checks out places where complaints are appearing, it's pretty obvious some of them are the work of persons unknown who, for whatever reason, seem to be padding the stats. (The competition, or perhaps disgruntled psycho or two??) I don't normally take issue with stuff you post, but I felt I had to speak up in this instance. Hope there's no hard feelings.
It would be a stretch to even call it statistics. Statistics requires you to evaluate a representative cross section of the sample you are studying and I do not believe that "people who own the subject Toyotas/Lexi and post on message forums" would be a representative sampling of the "total number of people who own the subject Toyotas/Lexi". But we have talked about this before in the Read Only forum I believe.
My analogy was meant only to indicate that the statistics included in the post I was responding to were meaningless.
My point was that the number of posts/complaints concerning a specific issue might, or might not, relate to how widespread the issue might be.
I was in no way trying to relate the seriousness of the Ford circumstance to those of the hesitation.
But now that you bring it up.....
I'm sure you have noticed the statements of a few posters that state that they believe the EXTENDED hesitation they are encountering can be replicated on any equivalent vehicle.
Having read the information at brakeassist.com I'm not certain I would disagree with those positions.
According to the information at brakeassist.com the ECU, in our case the engine/transaxle ECU, continuously monitors the brake activity of the driver and uses that history to differentiate a panic brake application from the norm.
Keeping in mind that ECU "memories" that are driver unique are erased each time the ignition is turned off.
So what if, like Porsche, the Toyota/Lexus/Denso skid control ECU is "learning" the braking and accelerator activity, charactoristics, unique to the current driver and somehow adjusting some of the skid control parameters accordingly?
Don't all of us now have some level of suspicion that the more serious level of engine/transaxle delay/hesitation is somehow related to specific driving method uniqueness?
I certainly do.
That would not only make the "flaw" a widespread problem but it would also mean that any one of us could encounter it just by doing something out of the ordinary, for us, with the brake of accelerator pedal.
I side with WWEST. If you are in a misbehaving vehicle, and the semi truck is coming at you at 55 MPH, and your car moves you into the intersection and then hesitates for two seconds, statistics are meaningless. The sphincter factor due to the approaching semi is fully meaningful. Whether this happens, 0.1% of the time or 0.001% of the time you push the accelerator is not significant to the driver of the vehicle at this moment in time. I say this from experience in a Ford Explorer which has occasional hesitation.
How many Fiero engine fires took place before it became a safety issue? Were engine fires statistically significant? What about Pinto gas tanks exploding?
The problem is hesitation does not leave many trails for the accident investigators to discover. BetterSafe
Apologize for getting off topic here, but I must take issue with something just posted questioning the statistical validity of complaints at Edmunds:
The number of complaints appearing in Edmunds "may not be a representative sampling of all owners out there". Wait a minute........is that a valid statement? Could that be just wishful thinking? Could it be that suggesting it isn't valid might be unintentionally ignoring something important? Or perhaps deflecting attention away from something they don't want others to know?
My thoughts: Isn't Edmunds one of the best known and most widely read cartalk sites on the planet? Edmunds gets input from all over the world, doesn't it? Infotrailers accompanying search requests here talk about "Millions and Millions" of posts in the discussion histories and archives, don't they? (Is Edmunds not being truthful?) Don't posters often say they post here because they know "everybody posts at or reads Edmunds?" Doesn't Edmunds get many thousands of hits per hour, and many more times that in a day?
I would suggest to anyone believing otherwise(or trying to convince others to believe otherwise), that the number of complaints in Edmunds is a pretty darn good indication of what owners are talking about (or concerned about), not just in the US, but in many other places worldwide.
Personally, I believe that information at Edmunds is an extremely significant database of information, not just about complaints, but a whole lot of solid information about automotive issues. Suggesting otherwise is simply ignoring reality.
What's my point? Simply this: The fact that only 40 or 50 hesitation complaints are logged here IS EXTREMELY SIGNIFICANT. It may not be a statisical benchmark, but it is a darn good indication that not many people here are expressing themselves about it--in a very large sampling of the car buying public.
Most drivers do not even know that Edmunds Forums exist. For example, I did not know of it up until about a year ago. I doubt if most drivers even have computers... And those which have computers do not have the time to surf the Edmunds forums like some of us geeks.
Therefore Edmunds data is clearly a subset of "all" drivers. I think the entries represent the poles: those who are really happy, and those who are really unhappy, and perhaps those that are paid to watch the forums. I do not know how folks like WWEST have the time to make his many many forum entries. { I suspect he is a wealthy retired eccentric millionaire with brain cells that get bored unless he is tracking down a technical issue. } The middle of the road people do not care enough to spend their precious "spare" time typing entries into forums.
Since I am no longer in the new car market, my wife asks me why I spend any time to review and comment in this forum. My answer is that I have been in a vehicle which hesitates, and I have had the sphincter moments, and I will spend some time to help others avoid similar situations.
At some time I think all of the major forum submitters should plan to hold a meeting in Vegas. We can party hard and do some driving at the track.
I enjoy the technical discussions immensely. I find the personal bickering childish.
Perhaps you're right. I won't belabor the point further. It's way off topic. If it's true though, then why bother attaching significance to anything posted here? That said, do I take your last paragraph to mean that contributing technical info must be SOP from now on, and any non technical input falls into the "personal bickering" category? (What ever happened to spirited debate--?)
PS-Vegas? Perish the thought! How about Carmel--maybe some golf at Pebble Beach?
"Why post anything...." This is the $10,000 question.
If I were Mr. Toyota, or Mr Ford or Mr. XXX, I would have staff who periodically monitored the forums to get feedback and ideas. If the reviews in Edmunds or other forums complained about the plastic gizzmo or uncomfortable handles I would pass that data to the design group for the next model change. It would be foolish for these corporations to ignore this free information from the public. As they listen, they improve their product, and increase market share. It is in their own best self-interests to monitor these forums.
However, good judgment must be used to evaluate individual posts. Some posts can be 100% false, arbitrary or misleading. Some posts could be placed by competitors trying to smear a reputation. In the case of the Toyota/Lexus forums, there are enough reports from individuals to give credence that there are unhappy owners. And some owners are VERY unhappy.
I would like to believe that any company will ultimately be influenced by these owners' complaints. It may take a long time: years. But I think they/we will have an influence. BetterSafe
I guess I responded to the wrong post. Shoulda been to billran. Your analogy was good in illustrating that trying compare the number of posts about a problem on the internet to the number of vehicles sold is pretty meaningless.
btw - i never wrote or implied technology is making all of us a little crazy.
you never did answer the direct question posed to you regarding a possible relationship with the manufacturer in question.
ok - so for years, people on Edmunds have been complaining about toyota and lexus vehicles, but interestingly, very very rarely other vehicles.
so - based on that - should we infer that this is mainly an issue with Toyota/Lexus models with DBW or not? is the difference statistically valid or not? i'm sure you'll present reasoning which is convenient to support your position.
anyone may look on the entire site here and determine which posters amongst all of us regulars actually provide actionable and useful information for fellow drivers... have you done so or just attempted to refute what you cannot agree with?
for you and billran to question motivation or attempt to reframe posts is overtly funny.
yeah, Toyota spokespeople have addressed the hesitation issue, and yes, a TSB has been issued.
admission, confirmation, legitimizing? more funnyness, i mean "crazyness"? agreed.
Comments
But for 2001 that procedure is likely meaningless.
Bingo. Just because it's on the web or returns hits in Google doesn't make it right.
Back on topic, the number of instances of hesitation/delayed downshift imply a design flaw (probably software as wwest opines) rather than a sensor quality issue or malfunction. I'm sure the PPM on sensors is in the single digits if measureable at all. I'm also convinced that driving habits and driver sensitivity play a part. My wife has never once complained about her Highlander and she drives it a lot more than I do.
Then there's the question of back and forth gas/brake activity in some of these circumstances.
We are on an exciting quest for knowledge. Let us stay focused on what we know about transmissions, and on how we can remove the unknowns. The discussion about VSC is important. There is an AVALON forum entry about the car braking erratically, and one response comment was that perhaps the VSC was attempting to take corrective action in behalf of the safety of the driver. If the VSC algorithms are given bogus sensor information, then, it can think that the car is going around a tight curve, when , in fact, it is going straight ahead. The VSC could elect to use braking on specific wheels to correct the "virtual" turn. Is this possible ? If so, I think I am glad that my cars do not have VSC. In my line of work, 75% of the software development has to address the error handling and all the non-normal situations. For example, what if sensor # 1 does not report in a timely fashion ??? What it you get an illogically high reading from sensor # 2 ??? These are real issues in the oil production and refining industry. We have to develop our logic to fail in a "safe" way.
However, in the case of VSC, which is in itself a safety system, I wonder how much validation it applies to the inputs that feed the VSC algorithms. I get gray hair thinking about this situation. Since VSC could affect brakes, engine, transmission, etc, I sincerely hope Toyota had their "top-guns" doing the programming and quality assurance.
>>on soapbox:
you're bringing up an important point about safety systems, i believe i remember reading two posts over the last year, one regarding a sienna that had a bad yaw or steering angle sensor where brakes modulated and put the vehicle in the oncomming lane...sensor had to be replaced, and another on an odyssey where a failed sensor caused the brakes to be engaged and slowed the vehicle in traffic. i might have the particulars a tad inaccurate. however the point is i believe these stability systems are actually going to be mandated in the future, and we have to be vigilant about the thoroughness of their design, implementation and test.
when we get in an unsafe scenario and the technology is working as designed, i'm confident they may be the difference between a scare and injury or death.
but, if they fail - depending upon the situation, we might be at risk.
i work in an industrial controls engineering capacity as well and i'm right with you bettersafe. as much as i think VSC will be a differentiator and life saver in some scenarios, i'm going to be a late adopter of that technology because of its complexity and it's costly fix if it fails, the possibility they will be repaired improperly, but also... today, i just don't trust the engineers to have tested all possible scenarios, sub-system interactions, failure modes, and confounding human response to degraded or conflicting indication or operation. just my opinion folks.
factually, engineers are not all versed in study of human factors in complex systems. the aviation controls industry has experience with this topic. this is why i have stated before, it's only a matter of time before the human factors community locks on the automotive industry.
human factors what they are, no matter what status or alerting systems we put in place to aid the operator, humans will ignore them, or possibly mis-interpret them... even go so far as to disable them (people pulling the fuses or indicator lamp on the Check Engine Light)...so even if we do our best to design a system that is robust, "silent unless certain", and failsafe, we also must consider the human element of the equation. let's also consider greed (gread for you wwest), and how some repair shops have been caught replacing deployed airbags with bad equipment or nothing but newspaper behind a airbag cover.
sometimes good designs go bad because of how the operator will react in different scenarios was not fully considered. same is true w.r.t. how the systems are maintained by others.
how do we know then when these systems are operating properly? for example, do we find out rather late when we are being put into another lane, or slowing in heavy traffic, or do we have telltale signs which we mis-interpret like perhaps experiencing retarded engine output, delayed or hard shifting?
<<off soapbox
I have yet to read a report of a ESC failure resulting in accident or injury (keeping in mind that even ESC can't change the laws of physics). OTOH, I'm certain that ESC systems have already saved many lives.
The only written complaints I've read about ESC (not counting any rants and raves by Edmunds' forum visitors)
I also wonder about that Avalon discussion where the car "went out of control" after a panic stop to avoid a rear ender.
Could that have resulted from simultanious application of brake and accellerator? (This was a Panic stop situation)
Or perhaps the car behind didn't get stopped in time and "ticked" a rear bumper--just enough to start things going south?
The owner talked about 65 MPH speeds,bumper to bumper, on a two lane causeway, rush hour......
VSC may not have been a factor in such a situation--there isn't much room for error in the conditions described.
It could also be argued that VSC may have worked by preventing a much worse situation, spin, rollover....
What do you think?
arosati, "Toyota Sienna Owners: Problems & Solutions (2004+)" #1304, 16 Feb 2005 6:27 am
I cannot seem to find the one on the Odyssey. It might have been Accord, or Pilot. Apologies.
If you knew how many engineers and programmers are involved in bringing an ABS/TCS/ESC system to market, you would not feel like you had to be a "late adopter" of this technology. Failures are more likely to be mechanical in nature (like the recent GM tone wheel corrosion issue) rather than software related
mechanical issues... right forgot those. throwing many engineers at a system design doesn't bring me more comfort. if anything - less.
I note that the yaw sensor on my 2001 is located on the outside of the body, above the rear axle, subject to damage by road debris, etc. By 2004 it had been relocated inside under the carpet near the door.
Evolution...
I think the current design of ABS is significantly flawed, it should never activate until VSC indicates that the vehicle is not following the "line" desired by the driver. But, who am I to criticize?
Two many cooks.....
There are those that think the Itanium processor went awry, and is now a failure in the marketplace, because the design group became too large with the HP and Intel group fighting over design superpremacy. The HP team won(???).
Any keep in mind that the engine/transaxle ECU module in all likihood contains more than one microprocessor. Cross communication between these processor to attain a common goal can be a design nightmare.
Do you believe the condition you're concerned about, namely differential braking, would be sufficiently strong enough to overcome or even restrict an attempt to correct by the driver?
Personally, I don't think so. Everything I've read re that possibility says no; braking pressures in those conditions aren't severe enough.
anyway, you don't want to be fighting automation that is active when you're cognitively loaded... same issue as with the hesitation itself.
I said that.
You must also admit that such failures are few and far between.
The question I asked had to do with VSC control module malfunction (paraphrasing): "Would the resultant differential braking be more that a normal driver could easily overcome by simply steering the vehicle".
I agree, a degree of automation would be present under those circumstances, but could it seriously affect a driver's ability to deal with it?
Same question applies to the engine hesitation issue.
PS. There's a very good book you might be interested in reading.
It's called "A Theory Of Cognitive Dissonance".
If you get a chance, look it up.
At the 24 Hours of Daytona, two weeks ago, car #86, a new Porsche 997 GT3 hit the wall on lap #17 at the "bus stop" with the top team driver, 10 years at the "24", at the wheel. He isn't/wasn't sure what happened but concluded that is/was likely the brakes locked up. Personally, knowing not much about the non-ABS brake system on the Porsche GT3, I think it much more likely that rather than a front brake locking up one of the floating calipers didn't float and the brake on that side simply didn't work.
Same result however, differential braking at the front at high speed.
Second answer has to do with driver reaction. What would the majority of drivers do in this instance having NEVER encountered the circumstance before?
Suppose the driver was already on the brakes at the time of the incident? In that instance wouldn't most of us simply apply more pressure to the brake pedal? Thereby exacerbating the problem?
Absent a firm grip on the stearing wheel at the instance of differential braking the steering wheel might just slip through one's fingers due to the feedback from differential braking.
We might take note at this time that VSC activation feedback is now being provided in much the same way a stick-shaker works in a commercial airliner to warn pilots of an impending stall.
On vehicles with electric power stearing it is now harder, actual resistance, to turn the stearing wheel in a direction that would exacerbate an overstearing condition that VSC is already working to alleviate.
But keep in mind that the circumstances wherein VSC might inadvertantly, falsely, apply differential braking to your detriment would only be on a RWD vehicle during an over-stearing event.
And that's not the subject of this discussion, at least from my viewpoint. My theories are concentrated on FWD vehicles exhibiting engine/transaxle delay/hesitation.
CLARIFICATION...
I'm not actually proposing that this is a full and complete activation of all aspects of the VSC system. Only pointing out the possibility that a flawed VSC firmware design, and a resultant failure, might be the root cause of these engine/transaxle hesitation complaints.
I think everyone will agree that of the two "events" VSC is responsible to help overcome, understearing and/or overstearing, FWD vehicles will generally be much more susceptible to understearing/plowing.
Understearing is most easily described as a circumstance wherein the driver is trying to turn the vehicle while underway. The front wheels are not aligned with the vehicle longitudinally, but the vehicle is not following, partially or fully, the "line", direction, set by that angle.
In other words the front tires have insufficient roadbed traction. That might be the result of engine driving torque or engine compression braking or it might be due to speed and vehicle inertia or even both.
So, what to do?
First, slow the vehicle.
The front tires have already exceeded their traction coefficient so any braking that would help will only be at the rear. And that's exactly what my 2001 AWD RX300's VSC system does in this instance, it applies braking to both rear wheels.
Second, remove any possibly for engine torque, leading or lagging, from interfering with the requirement for additional lateral traction. My 2001, not having DBW, starves the engine of fuel in this instance.
So the VSC system "disconnects" the gas pedal from the throttle valve while simultaneously "telling" the engine/transaxle ECU to belay any pending downshifts.
Any questions??
Psychology of Everyday Things (or it's retitled equivalent: Design of Everyday Things)
Set Phasers on Stun: And Other True Tales of Design, Technology, and Human Error
Automation and Human Performance: Theory and Applications (Human Factors in Transportation)
Designing for Situation Awareness
i think for the general public, the set phasers on stun book will be potentially an eye opener (and the easiest of the above to read), specially for those that blindly trust technology.
by the way, i would NOT agree control modules rarely fail.
Hopefully someone with a misbehaving vehicle will get to a mechanic with the proper OBD hardware, software and experience. . . . and we can get some hard information. I feel we have a long long list of possibilities, lots of good hypotheses, but not a lot of hard evidence.
I also agree there's been enough off topic discussion re VSC systems, so I won't belabor the issue further, except to say two things....., First,I wonder how many injuries (or worse) have been avoided by such systems; Second, We'd better get used to having them around because our Legislators are serious about making them mandatory for all vehicles.
To User777: Thanks also for your reply. Your sentiments about technology aren't shared by everyone, but they're your sentiments and you're certainly entitled to them.
I also suggest neither one of us can speak authoritatively re Control Module failure rates, except to say that blanket condemnations of all such systems is a flawed approach to solving problems.
IMO, by far the biggest "design flaw" in this entire discussion is the HFF (Human Failings Factor). Far more often than not, We are the authors of our own misfortunes--especially when it relates to automobiles.
I think what Bettersafe says sums it all up:"...... a long long list of possibilities, lots of good hypotheses, but not a lot of hard evidence"
my comment was to the point you made regarding your presumption that i'd agree the failure of these modules was rare.
Besides, it's the truth, I've said as much previously, and in this instance it was said far better than I could.
This hesitation issue is an great discussion, but well and truly long on hypotheses and short on hard evidence.
If it's a genuinely sincere objective to find solutions, a great deal more work needs to be done in the area of fact finding. (Emphasis on "Genuinely Sincere")
One more observation, for the good of all.
Telling others what's appropos or otherwise re their posts is best left to the Host.
Ain't that the truth. Just like the previous forum on hesitation that was closed due to constant bickering, this one has just about run its course, imo.
My prediction is that the issue will never be fully resolved, if for no other reason than the whole concept of delayed downshift/hesitation has an air of subjectivity about it. The most frustrating aspect of the discussion is wwest's refusal to acknowledge the correct spelling for steering
See ya all in other forums.
As regards what you said in the last paragraph--Yeah, you're probably right, it'll never get resolved. Definitely too much subjectivity.
Perhaps too much bias towards a 'cause of convenience' as well. It's next to impossible to resolve complex problems by working backwards from a single predetermined cause.
However, this discussion does have value, in that some excellent technical information flows from it.
As long as this problem exists and a solution has not been found, the forum is needed. New ideas and new perspectives on the problem will likely continue to come in and be analyzed until it is resolved. That is what it is for and it is why this discussion forum was formed, where it won't interfere with other discussions taking place on the specific model forums.
(The responses to the above post indicate that the gas pedal is not as described by this poster)
Possible question (variable) on bettersafe's questionnaire - foot postion on gas pedal when driving.
You write beauty to my ears. I bought a 02 Avalon new and haven't had any problems with the VSC. Why. Cause there isn't any.....IMO, the car buying public, not the industry itself ofcourse, would be better served to put in better componetry in their suspension and brake systems. Driver's would do better taking advanced driving techniques, and avoidance manuevers, emergency braking, etc. on their own vehicles. Then you could skip ALL the electronic gizmos and wouldn't have to pay for their upfront cost and repair costs.
However, we also have an 03 Mercedes E320 with electronic stability control (ESP in Mercedes marketing speak). I drove that car out to ski areas in Colorado in winter (with winter tires fitted) and the car performed amazingly well. I have experienced fishtailing and spin outs in rear wheel drive cars (not fitted with ESC) in winter.
Though there may be cases that electronic stability control (ESC) may fail and the fail safe may fail and cause injury or death, I would argue that the benefits of ESC (especially in rear wheel drive cars) GREATLY outweighs the risks. This is borne out in that I believe that their have been studies reporting that although ABS has no measurable statistical safety benefit, ESC does show a safety benefit.
If your standard is absolute perfection, then you miss out on the benefits. Example: you would stop taking all medication regardless of benefits because all medication has risks.
So to wwest who is a Porsche fan, I would HIGHLY recommend PSM (the Porsche version of ESC) and 4 winter tires for any rear wheel drive Posrche if driven in winter conditions.
I would also highly recommend ESC for any high center of gravity vehicle (SUV/Pickup/Minivan) to reduce the risk of rollover.
You surely got that right!!
I tried to say as much in my post 170, above. You said it better.
The weakest link in this entire controversy is the "Human Failing Factor". We ourselves are the "design flaw" smack in the center of this issue.
Like Pogo said "We've seen the enemy and the enemy is us".
In spite of more and more safety devices carmakers develop, drivers seem to find even more ways to negate their effectiveness and just keep on hurting themselves.
Personally, I would support mandatory driver training involving all your suggested techniques--and more!
Add to that mandatory driver's licence recertification--with the same training--every 5 years!
some of this technology has high utility, but is also a marketer's dream come true.
The PSM is a really good feature, as is VSC, since none of us can be completely "on our toes" 100% of the time.
I would to as long as it involved stationary driving simulators (as in flight simulators) wherein the driver could be put in DIRE circumstances, absent dire results, and thereby learn how to react properly.
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". You would not typically engage the clutch with a stick shift before moving the shifter into the "gate", selected gear position. Toyota's automatic gearbox is now preventing the engine from developing torque until the transmission's internal clutches for the selected gear ratio are fully and firmly seated.
This post does not concern, does not propose to address, the "standard" transmission shifting delay as disclosed by Toyota.
A relatively small number of Toyota and Lexus owners, encompassing model years 2002 through 2006, are complaining about extensive downshift delays. These complaints seem to primarily involve FWD vehicles or AWD vehicles with definite front torque biasing and 5-speed transaxles.
This post will focus on just what those few owners might be doing, or not doing, during the operation of the vehicle that might lead to an extended downshift delay period of 1 to 2 seconds.
Technology, ain't it wonderful?
BA, Brake Assist: Just what is this?
Apparently via studies by the automotive industry at large it was learned that some of us are not using out brakes correctly, at least not in all instances. As I understand the implementation, design, in an emergency or panic braking circumstances some drivers apply the brakes quickly, but for some unknown, unknowable, reason then just as quickly slack off the pedal. This might be due to reacting to, being unfamiliar with, the resulting pulsations from ABS activation, or it might be a "learned" reaction. Before the advent of ABS many drivers "learned" that severe, hard, brake application would often result in loss of vehicle control.
So the industry decided, on its own, that many of us would be better served if "they" did the "driving", at least in this instance.
Basically BA "watches" the rate at which we apply pressure to the brake pedal. If the brake pedal "stroke is rapid/quick but then brake pressure slacks off quickly then the BA function is activated and HOLDS the brakes into a heavy application for some predetermined period even with teh driver having slightly back off of the brake pedal pressure.
I may be somewhat wrong about BA in the above dissertation by the important point, aspect, is that BA is being triggered by the "rate of brake pedal travel/activation".
Porsche 997 EBD, Extended Brake Assist:
Same as above but with one added feature.
The processor "watches" the rate at which the accelerator pedal is released. If you lift the accelerator pedal rapidly then the system presumes (second guesses??), that your foot is now headed for the brake pedal and "pre-charges" the brake fluid pressure to move the brake pads from their otherwise retracted position and into "slight" contact with the rotors.
So, we now know that the Toyota/Lexus BA, Brake Assist, system is watching the brake pedal rate of travel to determine if brake is assist should be activated. And we also know that Porsche is watching the rate at which foot pressure on the accelerator pedal is removed.
So, given the above as factual, is it really so outlandish to think that the Toyota/Lexus drivers who are experiencing these extended downshift delays aren't somehow, in some fashion, causing these results?
I can tell you truthfully and frankly that my 2001 AWD RX300, when I'm trying to stop on a very slippery roadbed surface just plain does not want to come to a full and complete stop. The anti-lock braking system goes absolutely bonkers! The slower the vehicle speed declines in this circumstance the "busier" the anti-lock systems becomes.
But frankly, that's exactly the way it should operate, allowing me to maintain directional control right down to the lowest IPS (inch per second) travel rate. But what would happen if I suddenly slipped the transaxle into 1st gear? The idle engine speed would likely provide enough engine compression braking to overcome the ABS activity.
And that latter is exactly one of the aspects VSC protects you from.
If VSC detects understearing on a FWD vehicle it will quickly act to alleviate engine driving torque and prevent engine compression braking.
Why would rapid release of the accelerator pedal, or rapid release of the accelerator pedal and then quick application of the brake pedal "falsely" trigger a VSC activation? Or for that matter since the ECU in which VSC functionality is embedded is the "Skid Control ECU" and therefore handles all of the brake control functions, ABS/BA/Trac/VSC/EBD, might not a false activation of any of these functions be the cause?
Porsche is assuming that rapid release of the accelerator is a likely indication of quick subsequent brake use.
What if we follow that tract and see where it goes?
We already know that at extremely low speeds on a slippery roadbed engine compression braking can overcome the ability of ABS to keep the front wheels rolling. So suppose Toyota is preventing shift-downs and/or maybe even commanding upshifts in the same circumstances and for the same reasons. Porsche is precharging the brake pistons?
Just a couple of side issues.
Between 2001 and 2004 Toyota moved the two VSC sensors, stearing wheel position sensor and yaw sensor, from a direct connection to the skid control ECU to connection via CAN, Controller Area Network. In 2001 all network communications was via the proprietary BEAN, Body Electronic Area Network.
That might mean that Toyota (or Denso) is no longer in control of the VSC functionality. Bosch, maybe?
When I traded in my 2000 AWD RX300 for the 2001 AWD RX300 I did so primarily to get VSC and HID. I was told at the time that a new feature of trac was to provide a virtual form of front and rear LSD, Limited Slip Differential. I remembering wondering at the time that if that was so, brake apportioning being used as a front and rear LSD, then why hadn't they just gone ahead and eliminated the VC, viscous clutch, and used brake apportioning for virtual LSD implementation for the center differential?
That did!
Over the intervening years and the 50,000 miles driven I have come to the firm belief that the brakes are being used to apportion torque front to rear. Very early on I discovered that the VC was almost always "flaccid", almost never stiffened up enough to couple any significant level of engine torque to the rear. On a 4 wheel dyno it took 20 to 30 seconds before the VC stiffened enough to provide ~25% of the engine torque to the rear driveline.
All that is my way of saying, proposing, that there are, may be, implementation aspects of the RX330 engine/transaxle ECU and skid control ECU that are not advertised/published.
Just this morning I asked the service manager at Bellevue Lexus if the there was a method for disabling VSC. His immediate response was "pu
And even after I learned of the existance of several of the unpublished C-best options available for my 2001 RX300 the dealer denied their existance until I cam back with a printed copy.
So, what if a portion of the Trac firmware is "watching" the rate at which you release the accelerator pedal and, like Porsche, is somehow preparing the system for a subsequent brake application?
How many of you, given a stick shift on a FWD vehicle, would use engine braking to slow the vehicle if you weren't certain of a high level of roadbed traction? And what about downshifting a FWD vehicle for slowing?
What, no volunteers??
No insanity out there, none?
What if that is exactly what is happening with the owners that are experiencing the extended downshift delay? The Trac system is not allowing downshifts if it expects a quick, following, brake application.
What brake assist does is apply the brakes faster than the driver can if it senses a panic stop. It essentially changes the gain of the brake booster so one reaches maximum attainable brake line pressure quicker. Mainly a benefit to smaller and/or older drivers who don't have the strength or the reaction time to achieve maximum decel in a panic situation.
And who, if not the manufacturers, should decide what new safety features should be added?
I may be wrong but it's my understanding this "public announcement...admission" statement stems from unverified remarks by one poster in the now closed Engine Hesitation forum. The poster was alledgedly told this by a Toyota Service Rep during an arbitration.
Technically, if verified, that story might qualify as a "public announcement" (ie out in public), but anecdotal or hearsay remarks in Edmunds forums certainly aren't in the same category as official and widespread information sources.
To clear up any misunderstanding, do you know of any links pointing to a more official source, such as Toyota Corporate?
And as was discussed previously I consider the availability of the TSB as equivalent to a public announcement/admission.
Also note that there are really two "admissions" of concern here. The standard one to protect the drive train which everyone is subject too and likely as un-noticeable, mostly, as the up-shifts in my 2001. And then there is the "extended" one the TSB attempts to solve.
I certainly don't wish to take issue with your opinions on the matter.
However,your response does validate my thought that there's not really an official source " publicly announcing...admitting...hesitation is designed in...to protect the drive line"
I realize and appreciate that hesitation is a contentious issue with you and some others.
I just don't think it's helpful to have potentially misleading statements out there without some form of explanation with them to frame things in proper context.
There are two million cars on the road with the drivetrain in question.
Multiple searches have failed to identify enough complaints to amount to even one tenth of one percent of those cars. In fact, at best maybe 40 complaints for any specific model can be located, and many of those are obvious duplicate posts by the same people.
There are those here who, for whatever reason, want to portray this as a huge issue. The facts just don't support that.
Some say they can duplicate the problem in any vehicle, yet there are two million owners who dont report any problem at all. I am one of them, and I know two others personally.
So, what is the ratio of these admittedly flawed vehicles out in the public's hands versus the number of complaints or forum posts regarding same.
Minuscule??
There are times when statistics are meaningless.
The two issues are completely different, and I'm surprised that someone as astute as you seem to be would even suggest it.
Did you really mean to infer this issue is lurking just below the surface in all two million or so vehicles in question? Oh, and add to that, it's going to eventually emerge as a serious threat to everyone's life and limb at some time in the future? Come on now!!! :sick:
I certainly hope that wasn't your intention, because it would be irresponsible or worse--and you don't seem to be the irresponsible type.
Billran is right. There are over a couple of million of them out there, and darn few complaints.
The 50 or so here won't even register on the stat scale!!
Not only that, but it's fixable. As you and others keep reminding us, there's a TSB for that purpose!!
Furthermore, in the case of your Ford example, the NHTSA ordered a massive recall---not to mention a few devastating fires, multi million dollar liability actions, etc. That isn't even on the radar in this hesitation issue.
As Billran also said, if one checks out places where complaints are appearing, it's pretty obvious some of them are the work of persons unknown who, for whatever reason, seem to be padding the stats. (The competition, or perhaps disgruntled psycho or two??)
I don't normally take issue with stuff you post, but I felt I had to speak up in this instance. Hope there's no hard feelings.
It would be a stretch to even call it statistics. Statistics requires you to evaluate a representative cross section of the sample you are studying and I do not believe that "people who own the subject Toyotas/Lexi and post on message forums" would be a representative sampling of the "total number of people who own the subject Toyotas/Lexi". But we have talked about this before in the Read Only forum I believe.
My point was that the number of posts/complaints concerning a specific issue might, or might not, relate to how widespread the issue might be.
I was in no way trying to relate the seriousness of the Ford circumstance to those of the hesitation.
But now that you bring it up.....
I'm sure you have noticed the statements of a few posters that state that they believe the EXTENDED hesitation they are encountering can be replicated on any equivalent vehicle.
Having read the information at brakeassist.com I'm not certain I would disagree with those positions.
According to the information at brakeassist.com the ECU, in our case the engine/transaxle ECU, continuously monitors the brake activity of the driver and uses that history to differentiate a panic brake application from the norm.
Keeping in mind that ECU "memories" that are driver unique are erased each time the ignition is turned off.
So what if, like Porsche, the Toyota/Lexus/Denso skid control ECU is "learning" the braking and accelerator activity, charactoristics, unique to the current driver and somehow adjusting some of the skid control parameters accordingly?
Don't all of us now have some level of suspicion that the more serious level of engine/transaxle delay/hesitation is somehow related to specific driving method uniqueness?
I certainly do.
That would not only make the "flaw" a widespread problem but it would also mean that any one of us could encounter it just by doing something out of the ordinary, for us, with the brake of accelerator pedal.
How many Fiero engine fires took place before it became a safety issue? Were engine fires statistically significant? What about Pinto gas tanks exploding?
The problem is hesitation does not leave many trails for the accident investigators to discover.
BetterSafe
The number of complaints appearing in Edmunds "may not be a representative sampling of all owners out there".
Wait a minute........is that a valid statement?
Could that be just wishful thinking?
Could it be that suggesting it isn't valid might be unintentionally ignoring something important?
Or perhaps deflecting attention away from something they don't want others to know?
My thoughts:
Isn't Edmunds one of the best known and most widely read cartalk sites on the planet?
Edmunds gets input from all over the world, doesn't it?
Infotrailers accompanying search requests here talk about "Millions and Millions" of posts in the discussion histories and archives, don't they? (Is Edmunds not being truthful?)
Don't posters often say they post here because they know "everybody posts at or reads Edmunds?"
Doesn't Edmunds get many thousands of hits per hour, and many more times that in a day?
I would suggest to anyone believing otherwise(or trying to convince others to believe otherwise), that the number of complaints in Edmunds is a pretty darn good indication of what owners are talking about (or concerned about), not just in the US, but in many other places worldwide.
Personally, I believe that information at Edmunds is an extremely significant database of information, not just about complaints, but a whole lot of solid information about automotive issues.
Suggesting otherwise is simply ignoring reality.
What's my point? Simply this:
The fact that only 40 or 50 hesitation complaints are logged here IS EXTREMELY SIGNIFICANT. It may not be a statisical benchmark, but it is a darn good indication that not many people here are expressing themselves about it--in a very large sampling of the car buying public.
Therefore Edmunds data is clearly a subset of "all" drivers. I think the entries represent the poles: those who are really happy, and those who are really unhappy, and perhaps those that are paid to watch the forums. I do not know how folks like WWEST have the time to make his many many forum entries. { I suspect he is a wealthy retired eccentric millionaire with brain cells that get bored unless he is tracking down a technical issue. } The middle of the road people do not care enough to spend their precious "spare" time typing entries into forums.
Since I am no longer in the new car market, my wife asks me why I spend any time to review and comment in this forum. My answer is that I have been in a vehicle which hesitates, and I have had the sphincter moments, and I will spend some time to help others avoid similar situations.
At some time I think all of the major forum submitters should plan to hold a meeting in Vegas. We can party hard and do some driving at the track.
I enjoy the technical discussions immensely. I find the personal bickering childish.
BetterSafe
If it's true though, then why bother attaching significance to anything posted here?
That said, do I take your last paragraph to mean that contributing technical info must be SOP from now on, and any non technical input falls into the "personal bickering" category?
(What ever happened to spirited debate--?)
PS-Vegas? Perish the thought! How about Carmel--maybe some golf at Pebble Beach?
If I were Mr. Toyota, or Mr Ford or Mr. XXX, I would have staff who periodically monitored the forums to get feedback and ideas. If the reviews in Edmunds or other forums complained about the plastic gizzmo or uncomfortable handles I would pass that data to the design group for the next model change. It would be foolish for these corporations to ignore this free information from the public. As they listen, they improve their product, and increase market share. It is in their own best self-interests to monitor these forums.
However, good judgment must be used to evaluate individual posts. Some posts can be 100% false, arbitrary or misleading. Some posts could be placed by competitors trying to smear a reputation. In the case of the Toyota/Lexus forums, there are enough reports from individuals to give credence that there are unhappy owners. And some owners are VERY unhappy.
I would like to believe that any company will ultimately be influenced by these owners' complaints. It may take a long time: years. But I think they/we will have an influence.
BetterSafe
I still think Carmel would be worthy!!
btw - i never wrote or implied technology is making all of us a little crazy.
you never did answer the direct question posed to you regarding a possible relationship with the manufacturer in question.
ok - so for years, people on Edmunds have been complaining about toyota and lexus vehicles, but interestingly, very very rarely other vehicles.
so - based on that - should we infer that this is mainly an issue with Toyota/Lexus models with DBW or not? is the difference statistically valid or not? i'm sure you'll present reasoning which is convenient to support your position.
anyone may look on the entire site here and determine which posters amongst all of us regulars actually provide actionable and useful information for fellow drivers... have you done so or just attempted to refute what you cannot agree with?
for you and billran to question motivation or attempt to reframe posts is overtly funny.
yeah, Toyota spokespeople have addressed the hesitation issue, and yes, a TSB has been issued.
admission, confirmation, legitimizing? more funnyness, i mean "crazyness"? agreed.