Edmunds dealer partner, Bayway Leasing, is now offering transparent lease deals via these forums. Click here to see the latest vehicles!
Engine Hesitation (All makes/models)
As this issue has become a question for debate with various makes/models, this topic will be devoted to any/all that may be experiencing this problem.
Tagged:
0
This discussion has been closed.
Comments
With e-throttle " we gain better overall control..."
"It also simplifies "shift-shock" control by letting the computer ease off the throttle for smooth automatic upshifts..."
Statements by Paul Williamsen, curriculum development manager for Toyota Motor Sales USA.
http://www.sae.org/automag/techbriefs/02-2002/index.htm
(page down)
Translation: You fools don't have any idea how to manage the throttle so we're taking over and doing it for you.
Or:
When we need to shift the transmission to hell with what the driver needs or wants, safety concerns be dammed, we'll dethrottle the engine until we can get the transmission into the proper gear and the clutches fully seated.
so after looking at that diagram in the link you provided, i reserve to theorize (its a free country) for these Toyotas, that *perhaps* some vehicles with the drive-by-wire implementation have a hysteresis, non-linearity or calibration issue in either the accelerator (pedal) position feedback, or the throttle position feedback sensors.
if everyone has the same software and hardware, but only a percentage of people are reporting a problem, maybe they have a HW problem.
if so, fixing a HW problem with SW would be interesting, yet one doesn't know the true root cause. maybe there is a SW programming issue which can be mitigated with a patch.
oh nice. our cars are becomming more configurable and complicated as home and office computers.
mechanics will have to have IT training (maybe they already do).
anyway (more context for others) its interesting to me that people are complaining on the Highlander, Camry, and Sienna Problem and Solutions forums about this hesitation.
i wonder if it's a general design, implementation, software test, or parts supplier issue?
is this a Lexus issue too?
(2) Its implied intent was not to show Toyota
assumes drivers are fools or incompetent.
(3) The article is three years old.
(4) The article says their throttle by wire system was (in 2002) installed on Lexus LS430,Lexus ES300, and Camry. There have been few if any reports of hesitation on those models.
(5) The article goes on to say that the same system has been used for three previous years on Supra,V8 Tundra, Land Cruiser, and LX430, with a low failure rate. There have been few if any reports of hesitation on those models in the 5 years the system has been in use.
Wwest, your post underscores my previously expressed opinion on how the hesitation issue is being editorialized.
I hadn't considered any sort of characterization of anyone's observations. Besides, wouldn't answering a question like yours depend on individual posts?
Why would you ask such a question anyway?
I'm simply looking for relevant facts and pertinent data, regardless of the source, which might help me (and perhaps others) understand this hesitation issue.
That's all.
For Wwest........
I neglected to mention a couple of other facts from your link. It doesn't confirm Highlander's throttle by wire system is the same system referenced in the link, nor does it mention any tweaking, modifications, or improvements made to the system if it is used used in current HL models. I'm sure there would have been. Nevertheless, it doesn't shed much light on the present hestitation issue, but it it a very good explanation of how the earlier 2002 system operates.
>>
I don't think either one validates any theory, except that it does illustrate the principle that one can believe/quote anything one wants, but that doesn't always mean it's right, or accurate.
It follows that principle could also apply to anecdotal reports in cartalk sites, agreed?
>>
So about those anecdotal reports of hesitation - they aren't right or accurate, or these people believe and quote what they want, or what?
I assume you are keeping an open mind and giving them the benefit of the doubt that they are merely reporting what they experience.
BTW, my quote you referenced was about two totally contradictory newspaper articles/theories on the hesitation issue. One said one thing, and the other said exactly the opposite. My point was "which one is right"? My opinion was I didn't have a lot of faith in either one, and quoting one or the other as validation of either theory made little sense.
And I have never theorized that the hesitation problem exists on anything but FWD, or front torque biased AWD.
And please look more carefully at just what Williansen said.
Paraphased:
When the transmission ECU determines a need to "upshift" and the driver has the throttle position too high for a smooth shift sequence, the ECU will over-ride the driver's input and ease off the throttle postion until the upshift is completed.
And if you think that there are no hesitation complaints about the ES300 or Camry you need to take a closer look.
It is highly likely that the software core, base template, is still in use, but like almost all(exception being that in "Legacy" uses) software, it continually evolves, expands.
Apparently the original 2002 software design only eased-off the throttle for upshifts. at least that's all that can be stated factually.
The newer versions obviously have the added, evolutionary, capability to help prevent loss of directional control of FWD (or...AWD,) on a slippery roadbed surface. While at the same time still retaining the earlier capability of preventing premature failure of the transmission by easing off the throttle until the transmission clutches are softly and smoothly seated.
(2)There really aren't that many posted complaints with ES300's or Camry's in the 02 vintage--and I believe I did say "a few". Even later vintages of similar models aren't being overwhelmed with hesitation complaints.
The issue of"Hesitation" doesn't rate even honorable mention in most mass media Consumer Satisfaction Polls for those models, where very large owner cross sections are tabulated.
The same applies to LS 430's, Supra's, V8 Tundra's, Land Cruiser's, LX 430's---not much joy there either.
(3)I have no issues with what Willianson said; in my post I addressed what *wasn't* mentioned in your editorialized comments included with the link.
"Toyota developed an all-electric throttle-by-wire system for its Lexus LS430 luxury flagship that it has also deployed in its near-luxury ES300 and mainstream Camry family sedan."
Continued later in the article: "Earlier Toyota systems used a conventional cable as backup, but under normal conditions throttle position was handled electronically. Several years of experience with that system on the Toyota Supra, V8-equipped Tundra, Land Cruiser, and LX430 models emboldened Toyota to eliminate the cable. 'After a number of years of offering this, we've got the data on what the failure rate is,' said Williamsen. 'It is pretty low'."
I didn't look thru entire forums, but there apparently are very few hesitation issues raised for any of these models.
come on. you're an engineer.
what can you definitely conclude based on a limited number of anecdotal reports found in some e-forums?
you want facts and objective quantitative information...but you're not likely to acquire either of the quality you desire in an e-forum or a Consumer Satisfaction Poll.
you know that there are a number of people that use a high-tech artifact, and assume it is their fault for not operating it properly when it doesn't work.
how could they possibly know for example the designer's model of the artifact, when all they have are the affordances and observables to form an incomplete user's model? granted there is the owner's model - but that is going to be short on technical detail and for a reason. the user shouldnt have to know how the system is implemented. it should work, and to a good extent the way they would expect it to.
..by which in this context i mean - how does one expect users experiencing the hesitation to formulate a designer's model of what is going on when all they have is the pedal, the sound and speed of the vehicle, what they feel in the seat... they are not designers. they are users without that information at their disposal.
The approach is admittedly not perfect. I ended up with 210 hits, but the search engine then reduced the number automatically to 107 hits by eliminating urls that were sub-categories of the urls left in the list. (Such as numerous mentions of the same basic edumunds site.) Of course, my parameters may also have eliminated a number of other hits that actually did discuss the Highlander problem. So someone with a lot of time in his/her hands may want to repeat the search using fewer restrictions, and then go into each link to see if it applies.
Of the 107 hits I ended up with, there were maybe 50 that actually dealt with the hesitation problem that Highlander owners have been discussing. Two were in newspaper articles, and the rest in various forums. The earliest complaint about the hesitation problem that I found was in a competing forum and was dated November 24, 2001.
Maybe these results are not overwhelming, but it does appear that many people are talking about the issue in many places, not just in edmunds. I suspect that there soon will be more discussions about the hesitating Highlanders in additional newspaper and magazine articles. While I don't have the problem (I have a 4-cylinder Highlander), there is enough evidence out there for me to believe that the hesitation issue is real. I would hope this new discussion thread can help determine the source of the problem, identify why some people have it and others cannot replicate it no matter how hard they try, and inspire the car manufacturers to work quickly to find a resolution.
Toward this end I think it would help if all posts include 5 pieces of information: (1) Make of vehicle, (2) type of engine, (3) FWD or AWD, (4) type of transmission, and (5) hesitation experienced or not experienced.
I know there is some hesitation at times with the 2004 4-cylinder Subaru outback because I experienced it and because a friend with Subarus said "Yeah, they do that." When I was looking at vehicles early in 2004 there was no mention of hesitation on the Subaru forum that I recall, but also nothing in the Highlander forums at that time. When I have the chance I think I'll go back into the Subaru forum and see if it's a topic of conversation there. Or are any Subaru owners reading this who could save me the trouble?
i'm sure there are numerous means that result in engine hesitation in a vehicle with a conventional cable-throttle.
probably, KarenS, the host expected the discussion to be open to accomodate all sources.
But them again it is most definitely rear torque biased!
But then maybe that's because the weight of the engine is also at the rear.
"Driving a hybrid is a bit different as you feel a fair amount of engine braking once you lift your foot from the accelerator pedal. Also, there's an annoying engine hesitation during initial acceleration.
Once you get used to those little idiosyncrasies in driving a hybrid, and you see the unbelievable numbers from the instant fuel economy gauge, the quirkiness becomes much less objectionable.
Our Civic Hybrid tester changed the way my co-tester and I drove. We were so intent on seeing big numbers on the instant fuel economy gauge that we accelerated with less forcefulness, and coasted as much as possible while approaching stopped traffic."
So...inasmuch as I don't like to speculate, here's a question worth considering: Any merit to the idea that Owners often need to get used to certain idiosyncrasies with their vehicles?
Answer: Hasn't it always been thus--to a greater or lesser degree?
First of all, many people have a different idea of what a "hesitation" is. I can tell you from my experience as host that this means:
1. Car downshifts abruptly but doesn't "move out" (actually caused by too large a gear gap between overdrive and 4th)
2. Delay in downshifting (actually a transmission issue, not a fuel delivery issue)
3. Engine missing (could be anything here)
4. cold idle problems that later go away.
So on and on.
Also, practically all the "evidence" you can google is "anecdotal". By "anecdotal", we do not mean a put-down of any kind. The "anecdotal" data could be totally correct; however, if precise and documented scientific methods have not been used, then it's "anecdotal".
So unless you randomly sample say a Highlander or a Pilot or a Lexus 300 series, and do a LOT of samples, and maybe even switch drivers around, you really don't know what you've got here and you never will.
It could very well be that the number of Pilot owners complaining about engine hesitation is consistent with the number of complaints one would expect per 100 cars made of any make. Maybe Pilot owners come here more often. Maybe they yell louder. Maybe they are right. How can you know unless you have really overwhelming evidence.
Even Federal recall campaigns, as massive as they might be, aren't correcting actual defects, but really mostly making upgrades to correct *potential* defects that have appeared in a small sample.
i hardly believe the Toyotas with the DBW systems are designed with the hesitation to "teach" any of their owners anything, except a lesson in confusion, frustration, and as several posters have indicated a lack of confidence in the technology and a general wearyness about their safety in certain scenarios.
i mean, if i am to believe all the other stuff you are saying about hesitation (would that be a failure as you were using the term?) being so rare, then most certainly it's not by design and not for the purpose of educating the userbase.
Were I the proud owner of a new RX330 I would be hounding the dealership and Lexus on a daily basis were I to experience a 1 to 2 second delay in engine revs increasing when applying WOT.
Or maybe I would just retrofit the DBW to a mechanical linkage from an earlier model.
My brand new 1992 Lexus LS400 was parked in my garage for over a year, unused, due to the many unexpected instances of the windshield suddenly fogging over almost completely. Once I lost the lawsuit I decided to figure out for myself why Lexus had made such a stupid and dangerous design mistake.
Not only was I able to come up with a fix for the LS, but I now have 5 patent applications pending as a result.
Yet very little has been done to logically, factually, and objectively unpack the issue.
One thing is crystal clear though--"hesitation" means many different things to many different people, and that only confuses the issue further.
Perhaps, as someone has already noted, this may not be the place where logic, fact, and objectivity are likely to occur. Perhaps my expectations in that context are unrealistic, who's to say.
To User777: I'll try to answer your obviously leading question (actually it sounds more like an indictment IMO!)
I don't believe those who make autos, auto design folks, or auto engineers in general do what they do to "teach" people confusion, frustration, lack of confidence in technology, or concern about their safety. They just don't, period. They're just doing their jobs.
As regards the safety issue, I have read some impassioned stories about people narrowly escaping death or injury because their vehicle hesitated on merging or passing, etc. I fully understand where that scenario might scare the heck out of someone. But perhaps getting into those scenarios can (and perhaps should) be avoided where possible--regardless of whose vehicle you own. My thought are: why would you do it in a high powered vehicle if you wouldn't do it in a simple 4 banger Neon? I'll wager people who do it with more powerful engines(ie the HL V6)would probably answer "Because it's powerful and I expect I can do it!" They may be right on that score, but believe me, there may come a time when they'll be dead right, hesitation or no hesitation!
There's an oft repeated aviator expression that might also apply to WOT types (I've substituted "drivers" for "pilots"):
"There are lots of old drivers, and there are lots of bold drivers, but there aren't many old bold drivers."
Actually, how often is WOT really necessary anyway? (Please note, the emphasis is on *really necessary*)
remember the Airbus crash several years ago during the Paris Airshow, when the test pilot commanded full throttle at tree-top level, after pulling up from a steep dive, but the Airbus control system designers implemented an authority envelope which usurped pilot control? essentially they hadn't envisioned the scenario which was presented?
people have a mental model that is really simple w.r.t. the throttle: I press the gas, and the engine revs higher. period.
with the introduction of vehicle stability and the like, that is no longer the case is it?
now I'm not saying people are experiencing hesitation because of programmed limits to driver authority in this context. no.
if you are comming to a stop-light which changes color, or you're merging and you demand more power by stepping on the gas, you *expect* the vehicle to respond by speeding up. yes/no?
when it does not...the other consequences i mention occur. it's human nature.
it's either a bug / glitch / defect, or a faulty design IMHO. [you design a system to support a consistent user model of the world. in this case, it (cause and effect which has been learned up from potentially decades of driving cable-throttle systems) doesn't happen for a period of time]. that's faulty.
let me ask you this: you're at 10K feet, flying instruments (but you don't have TCAS) and the tower radios to you to pullup for traffic immediately ahead of your position, range about 1/4mile. you pull back on the stick but nothing happens...
what do you think? does that plane get a good looking over when you make it down on terra firma? do you trust flying in it?
be honest.
As I accelerated, not heavily by any means, out of my residential street onto the main thoroughfare I had to cross some plastic striping designating a crosswalk. If the plastic was dry, all was fine and dandy. Wet, and the rear wheels would spin, ever so briefly, I would hear the brakes being applied to counteract the wheelspin and the engine would be instantly dethrottled.
And now there I sat, out in front of the oncoming traffic and NO engine. It took several seconds for the Trac ECU to "unwind" the dethrottling stepmotor.
I developed the habit of turning off the Trac as soon as I started the car.
Years later I purchased a 2000 GS300. It didn't take very long to discover the Trac firmware had undergone an evolutionary change. With wheelspin the brakes would be applied immediately but the dethrottling was delayed just enough to allow the driver to react and lift the gas pedal on his own.
If you didn't react in a reasonable time you were dethrottled.
The firmware designers and specification writer are learning as WE GO!
So if we have 100 Pilots, and 90 accelerate perfectly, 7 give the drivers some sense of "hestitation" some of the time, and 2 are ultra sensitive to wet streets and over-reactive SC systems and one really does just go BURP when you stomp on the gas no matter where you are or what your car is doing, then I see all those separate conditions as pretty normal for a mass produced product. You have:
a majority of full function
a small percentage of user mis-use or mis-understanding
a small percentage of annoying but not really significant design flaws per 100 items
a really small percentage of a true defect.
User777 asks: "you're at 10K feet, flying instruments (but you don't have TCAS) and the tower radios to you to pullup for traffic immediately ahead of your position, range about 1/4mile. you pull back on the stick but nothing happens..."
Answer: Under that scenario, chances are you're already dead. You have about 1 second to react at closing speeds of 300 plus MPH.
Also, in that scenario, ATC would culpable for violating FAA regs for aircraft separation. It would only happen if ATC was negligent.
Plus..and this is a big "plus", the snag that caused the delay or inability to pull up is discrete and unexpected (not an ongoing situation), probably due to either failure of the autopilot altitude hold controller, or a malfunction in the aircraft's elevator control linkage.
Yes, the snag would immediately be corrected--but only if the incident didn't result in my demise.
I should also advise that I am a Transport Canada Hearing Officer (aka Arbitrator) for Aviation Matters. The scenario you describe would probably result in a heavy fine for ATC Administration, and the actual ATC Controller would be invited to leave.
One more thing. The Paris airbus incident was judged as pilot error.
Don't ask me any more aviation questions SVP. They have nothing to do with the hesitation issue;(a)I won't be able to resist them; (b)It will just bore others to tears; and (c) Mr. Shiftright will not be pleased!
i look at it like this:
the cars are getting more complicated. sure - there are additional features (specially safety) we can all benefit from. companies have to migrate to DBW to implement the framework for stability control right?
the problem is...they are getting rather difficult to diagnose.
frankly, i'm not thrilled with a vehicle manufacturer having to issue patches... you see it all over. ECMs, TCMs.
flexibility to correct unforseen issues in the field? sure!
but i wonder these things - did these designs get sufficiently tested before being fielded? will they be reliable long-term? will the shop have enough insight to be able to fix a problem? will it be expensive to maintain? just as important: can i develop a good mental model of what the vehicle is doing (in otherwords, does the automation support me - or burden me with what i cannot explain)?
And sure, one's attention would be piqued--that's a no brainer for gosh sakes! I don't think anyone would deny that.
I think I'll just sit back and observe for a while.
One final observation.
Read post # 29 again and again---and then one more time.
There's the answer y'all are looking for, whether you agree with it or not. And the author isn't being uncivil, accusatory, prejudiced, apologist, insensitive, spiteful,....yada, yada. What he has said is reality.
http://www.pittsburghpostgazette.com/pg/04345/424551.stm
http://www.indiacar.net/news/n8100.htm
Lexus ES330’s having transmission problems Friday, December 10, 2004
A new “drive-by-wire” system is Lexus’ answer to the hesitation problems that some owners are complaining about. Consumer Reports stepped in and said that they believe it may be something else (CR is the Inspector Clouseau of mechanical problems). Lexus has stated that they are aware of the acceleration hesitation problems. “After firm pressure was applied on the accelerator petal and trying to accelerate quickly”. Or as a normal person would say, “I pressed on the gas, fully expecting the car to go and pull out in traffic and nothing happened.” Models are the 2002-2004 Lexus ES300/330 models with the five speed trans.
that's one problem when a complex system's operation doesn't line up with user expectation and prior learning...there is mental energy spent (sometimes during the event) trying to reconcile the experience.
kirstie_h
Roving Host
Host, Smart Shopper & Future Vehicles discussions
MODERATOR /ADMINISTRATOR
Need help navigating? kirstie_h@edmunds.com - or send a private message by clicking on my name.
Share your vehicle reviews
But the bottom line, conclusion by the investigating body, was that had the "firmware" allowed the control surfaces to follow the pilot's input those people would be alive today.
According to Volvo, the XC90 AWD system actually routes the majority of engine torque to the rear when accelerating into a turn, and then back toward the front as you exit the turn.
The RX330 AWD system doesn't have this ability so the next best thing is to reduce the engine torque to the front wheels when accelerating into a turn. The tighter the turn and/or the more throttle you attempt to use the more radical, dramatic, the VSC's dethrottling effects will be.
that's why i was thinking HW, ie. the accel or throttle position sensing. however, in your senario, if stability control is getting in the way, *perhaps* some vehicles have marginal or incorrectly installed yaw-rate sensors.
to one of pilot130's points, without facts its basically just a guessing game (i can be diplomatic KarenS).
I owned a MY2000 AWD RX300 prior, and upgraded to the 01 to get VSC, Trac, and HID. Insofar as I can determine from the 2000 shop manuals the 2000 model does not have the same coastdown upshift pattern as the 2001.
So, was I one of the very few that went directly for a 2000 to a 2001 model and therefore had an experience base, thereby a special reason to notice the "bump from behind" or the "slingshot effects" in the newer model?
Even today I admit that I have grown so used to the effect I have to remind myself to take special notice if I want to determine if the effect still exists.
And hey, if my wife is with me in the 911 I NEVER "hard" accelerate into a turn. And she is ALWAYS with me in the RX. And frankly the only time I can even remember "flinging" the RX into a turn (well, attempted to anyway)was in a large empty snow covered parking lot to check out the dynamics of the AWD and the VSC/Trac system.
I know it's a FWD so otherwise where's the fun?
How many of us, or how often, does anyone quickly go half throttle or more just before coming to a full stop. And undoubtedly even fewer that go half throttle or more in this same circumstance while also turning. Wouldn't that constitute an unusually aggressive driving style for buyers of this particular SUV?
This is a Lexus SUV, nice comfortable and quiet ride, not a vehicle the typical owner would be expected to "treat" like a 67 Mustang, or even a BMW X3, maybe.
Would LOVE to get my hands on the stearing wheel of an X3 in that same afore-mentioned parking lot.
Is the firmware in these SUV more tightly "wrapped" due to this?
The circumstances of the hesitation occur so rarely, and maybe for most owners even never. So it is likely, possible, that no one will be able to answer your question, and certainly not enough answers to make a firmly based conclusion.
Besides which, in the beginning, how many of us would just write it off as a weird anomally, forget about it, until it happened enough times, or in a noticeably unsafe circumstance, to put it in the "front" of our minds?
Am I over-stepping?
I'm still observing BTW--something of substance may come by. Anything new would be welcome, I'm sure. Keep up the good work.
however, from a few anecdotes reported, those individuals noticed it pretty soon after getting the vehicle home (but unfortunately, not on the test drive).
Host