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Engine Hesitation (All makes/models)
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Comments
http://automobilejournal.com/content/view/83/1/
http://www.acarplace.com/reviews/2005/camry.html
“The 3 liter V6 engine provides 210 horsepower, but most of it comes at high engine speeds, so that there may be a delay before you actually get moving. Indeed, the transmission tended to have a substantial delay before downshifting when faced with sudden throttle changes, resulting in a condition not unlike turbo lag. This could be disconcerting when moving from a stop sign onto a busy, fast street or highway. Because the transmission changes the way it shifts to meet your driving style, it slowly became more responsive as we drove to match our preferences; the prior driver had apparently been more gentle on it (we've always wondered why they don't allow dual driver preferences for the transmission, as well as for the seat positions). However, we never got around a substantial hesitation on heavy acceleration, most likely because the engine's power is largely made at revolutions.”
A similar one (Lexus RX330) at http://www.toyoland.com/lexus/rx330.html
“The 3.3 liter engine from which the RX330 presumably takes its name is fast in sprints, but since it makes most of its power only in at higher speeds, there can be a fairly long lag before acceleration, since the transmission has to downshift. Given the transmission's preference for staying in higher gears as often as possible, and the delay between hitting the gas and downshifting, this means that the RX330 often does not feel responsive on the highway.”
If the reporter isn't reporting on his own experience, I would discount it as "evidence" of anything besides a rumor--unless the reporter is linking to a solid first-hand experience. The best reports would be those coming from impartial sources, which would have to exclude owners and dealers' employees. However, owners and dealers points of view are worth something, but just not as solid as an experienced tester with no axe to grind or product to protect. If I'm testing for Motor Trend, and my Lexus is acting up, I just note the facts and then turn the car back in...no sweat, no money out of my hide.
Another point:
People with overdrive automatics should NOT be in overdrive in city driving. I think this would eliminate 50% of the complaints right there and may explain the mysterious coming and going of the problem. In other words, I'm beginning to speculate that some of the hesitation problems are definitely real (especially those noted at freeway speeds) and some are only related to improper gear selection. If you stomp on the gas in 5th gear at 28 mph on ANY car it's going to fall flat on its face most likely.
If any of you experiencing this problem are in 5th gear in urban traffic, try using 4th only and let us know what happens.
I see these answering posts as really saying *You think the Gazzette bad news article is weak, here's some more bad news.*
Well, I see the next 4 articles as weaker than the Gazzette article. Why??? Because the quotes do not tell the story of wwhat else is in those articles. Those articles are all complimentry of the Toyota line, not negative. They do not say the hesitation thing is a bad problem. In fact the mention of hestitation is just a small part in the articles. The gist of those reports is very flatering to Toyota.
I have a hard time understanding posting things like that and saying it is helping anybody. It seems to me it is just deliberatly intended to mislead people. Those were all good reports and they were not posted in full. If they had been posted in full it would have been a different story.
Hesitation IS the topic of this forum, so these articles are relevant to the discussion. I totally agree with other posters that Toyota's and Lexus' are great vehicles, the only stickler in the new models being the hesitation. Clear that up, they could be darn near perfect.
Just keep the topic in mind and it may not bother you so much that I or others quote only the paragraphs relevant to the topic (it may pique interest so one can read the entire article for more info).
1. The Post-Gazette articles are newspaper reports, not automotive reviews, so I think they are written in the appropriate perspective. I really don't want to comment or criticize on the quality of the writing (isn't that akin to commenting on spelling errors or typos in forums like this?), but he did interview several owners experiencing the problem, a Consumers Reports rep, and a Toyota rep, so he included several perspectives on the issue. I think in that way, the stories are balanced, particularly the later ones where he has added information.
2. The other links I provided were Automotive Reviews. Completely different animals. They are speaking of the auto as a whole and not just a specific problem. All the pros and cons are mentioned, based on the perspective of the reviewer and the test models driven. Not sure if these reviewers have any bias or not. I didn't dig that far into it and don't plan on doing that. They are just thrown out there, FYI, draw your own conclusions.
(And yes, kraft, there are many positives in these reviews, I provided links, not just quotes, so go read the whole things. I didn't hide anything or cover anything up :shades: )
I find I can't come up with answers to Kraft's question--how do constant reminders of the same old info really help anyone?
How does repetitive showings of the same old same old shed any light on the subject?
Like I said last nite, that Post Gazette article has appeared so many times in so many forums here that anyone can almost recite it from memory.
What purpose does that serve?
And even the 4 new revelations don't really say much--especially when the entire documents are reviewed. They are indeed, overwhelmingly positive in context.
Compare the quoted snippets with the whole, and the quoted info is dreadfully thin.
I also think it's not terribly informative to just "select" certain quotes that only convey negatives.
It really seems more "manipulative" than "informative" to do that, IMO.
Earlier I showed how evidence is assessed in an Arbitration
Arbitrators look at (1) Admissability, (2) Relevance, and then (3) Weight.
These quotes don't make it as admissible because they are either anecdotal or opinion.
But if they did qualify, I guess you could call them relevant. (Hesitation gets mentioned).
If both those criteria are met, then you go to weight. Sad to say, but these quotes don't weigh anything at all. They are nothing but "argument", and argument isn't evidence, unfortunately.
The short version is, simply put----Scoti1, if you feel you must tell stories in this discussion, then tell the whole story, not just the part which satisfies your motives.
Then you'll really be helping people.
Poor writing leads to misunderstanding and in my case anyway completely destroyed my regard for the writer's credibility. He's not even reading his own stuff, so why should I?
My 2001 AWD RX300 has the trailer tow package and I removed the hitch within a few days of purchasing it new. There is no recommended transmission fluid change or flush in the owners manual so I would presume this to mean the fluid is good for the life of the vehicle.
At 38k miles my transmssion fluid was looking dirty and smelled slightly burned. I email Lexus about this and their response was talk to the dealer. I knew what the dealer would say regardless so I tried emailing again. Got the same result.
So I went, hat in hand, to the dealer. I was told that Lexus had revised the recommended maintainence schedule and I now needed to flush and replenish my transmission every 15,000 miles. I was assured that this was actually a factory directive.
So I drained 4 quarts of very dirty fluid and installed 4 new quarts purchased from Lexus.
Within a week the transmission fluid appeared to be just as dirty as before.
So now I have 4 more quarts plus a pan gasket out in the garage awaiting then time I have to do the whole job all over again, more thoroughly this time.
Also, scoti1, your posts are some of the only on topic ones on this site. Keep up the good work.
Now that's a strainge position to take. Are you suggesting that we should expect a 5-speed auto to perform with less agility than a 4-speed auto? That's going to be hard to accept for many, many people. M-B, BMW, Honda, Nissan, and Toyota all market these as an improvement to the "old" 4-speed. Most of them make it work, too. What is this extra complexity supposed to actually give us? Lower engine RPM's at cruise? Is that it? C'mon, all of our computers that we're reading and posting with, have all gotten much faster in the last 4-5 years. Why can't the trans handle a fourth shift as adroitly as the first three used to be? I drive a great 4-speed auto in my 2002 Highlander. My thinking is - don't add a 5th gear unless you add the brains to make it work efffectively.
Could this be the early 70's again - poor driveability due to under-tested systems? Then, it was smog controls - now it's VSC, TRAC, ABS w/Brake Assist, 5-speed autos, and Tire Pressure monitors - all fighting for the same bandwidth in the vehicle's ECM's and data streams. Me - I'm waiting for Gen 2...
Let 'em all pound on their keyboards with empty rhetoric - but don't let them draw you in. I'm watching this forum nearly every day, as if it was a modern Poirot episode. Or maybe it's Monk. Not sure - doesn't seem to give to be much programming between commercials. I can't wait to see what the fix is, and how loudly it's proclaimed. Maybe the 2006's will all be perfect, and we all trade up.
In any case, this Forum is an invaluable tool to those who actually have the problem, and/or have faith in the integrity of the postings of those who do. The rest - I ignore 'em.
"A sometimes-indecisive transmission is the one mechanical hiccup noticed during the test drives. In stop-and-go traffic or cruising at walking speed looking for an address or street sign, the transmission can't settle on a gear. Little jerks and shudders come through as the transmission hunts for the right ratio. Disappointing in such a well-done car. "
So what I was trying to say is this....IF you are experiences a hesitation on downshift WHEN you have put the car in 5th (OD) and you are say only turning 2000 or less rpms, then your hesitation is normal and you aren't driving the car correctly. This goes for any car made with a 5 or 6 speed manual or automatic. You don't use overdrive at low rpm---it doesn't work and actually can harm the transmission or engine if you do this habitually.
Now please, I put some IFS and WHENS in there for a reason! I am not trying to excuse Toyota, I'm only trying to weed out the cases which aren't valid criticisms, not the ones that are valid.
It is certainly true that OD mode is not for acceleration, pulling heavy loads, nor up a fairly steep incline. There is only one of these circumstances where the driver would be expected to interact and disable OD. That is when you're towing, or carrying, an unusually heavy load.
Under the circumstances being described wherein the hesitation symptom is encountered any reasonable automatic transmission design will immediately downshift, out of OD, during acceleration or climbing a steep incline.
As the Keebler "gofer" says "what part of "automatic transmission" (magic oven) do you not understand, Dude??"
I agree about the use of OD - when stuck in traffic, I turn my OD off on my '02 4-speed Highlander - it's just a button, after all. So we agree on that. But I'm guessing that you are also like me in that you like driving a manual trans. This is my first auto in 14 years, but it's one of the best auto's I've driven. In a manual trans, it is true you shouldn't lug the engine by shifting too high, too soon. But we're now talking about an automatic. It's supposed to prevent lugging by shifting and controlling OD - AUTOMATICALLY. Toyota's Owner's Manual, like most Owner's Manuals, don't really go as far as your statements. Essentially, they tell us to put it in top gear (or D) and drive - exceptions are noted for snow starts, and using the OD cancel as a way to shift to 3rd for descending long grades.
I agree with cancelling OD in your cited situations, and they do provide an easy way to do that. It's true that canceling OD will probably improve the hesitation issue. But the fact that this would need to be done speaks to the gap between what an automatic trans SHOULD be able to do, and what it really does. This hesitation may not a real "flaw" to some, but I hope Toyota doesn't stop working on this issue. Other companies seem to be able to do a better job with 5-speed automatics.
An automatic overdrive is not "designed" to downshift smoothly from 5 to 4 at very low rpms because it's not supposed to BE in overdrive at those rpms. That is a driving fault and you go to the penalty box for it
That's why the button is there...it's the "help, get me out of here" button for the transmission.
It's pretty clear to me that something is going on to improve fuel economy, and/or reduce engine compression braking, within our transaxles when we release the gas pedal. That "bumped from behind" feeling as I come to a stop, or the "slingshot effect" as I slow, coastdown, from a higher cruising speed, must be the result of the engine/drivetrain coupling being somehow "loosened".
The shop manuals clearly indicate that stepping on the brake pedal ALWAYS results in releasing the lockup clutch, for instance.
But on a completely separate subject, what about that lock-up clutch within the torque converter? The lock-up clutch first came into being in the mid to late seventies so automatic transmissions could have a "true" overdrive mode.
Nowadays the lockup clutch is serving lots of extra duty as it is being used in almost the same way one would use a manual clutch. Disengaged for shifting, acceleration, and to prevent lugging and/or stalling of the engine at low road speeds or when stopped.
If we disable OD does that also disable the lock-up clutch for all gear ranges??
If it does then I can see how disabling OD might help to prevent engine hesitation that results from gear shifting "indecisiveness" on the part of the engine & transaxle ECU.
Well that's a good point certainly and quite interesting. It should automatically fall out of OD when rpms are low enough....I'm sure it does at some point, but perhaps it's "hanging" way too long.
If that's the problem, then as an owner I wouldn't mind just shifting to #4 and keeping it there until I get to a freeway. That's what I do with every 5 speed auto I drive anyway.
But apparently that isn't the whole problem as people are experiencing this at freeway speeds...unless they are coasting way down on the rpms. If this strong hesitation happens at say 60 mph, that's totally unacceptable then. But at 25 mph in 5th gear, I could live with that and compensate for it.
Between me and youse guys, here's the title of the USA Today article where that selective quote is taken:
"New Avalon's Close To Perfect"
Sure paints a different picture than the quote, doesn't it?
Now, can youse guys tell me again how fanning the flames of discontent really helps anybody?
BTW, here's what the article starts out with:
*"It" being coming up with the best, big, Americanized four-door sedan ever to turn a wheel in service of everything from groceries to granny. The latest Avalon is a stunning piece of work; the kind of Yank-mobile that, had Detroit been building it all these years, would have denied the Japanese the significant foothold they now have in the mainstream American car market.*
My My, Quite a different picture from the message Scoti1 was suggesting.!!
funny how most other manufacturers with DBW technology just aren't having a problem with this, and yet, a common thread around the 5-speeds with DBW for a certain manufacturer is problematic.
hmmm.
also interesting - haven't 4-speeds had a OD button (on some models)? Gee - they don't need to be down-shifted to prevent lugging do they?
the van i drive is very smooth under all these scenarios, gets good gas mileage, and when i make a demand for power - that's what i get. just what i expect and want and need in the scenarios mentioned.
err - no - it doesn't have DBW throttle control though. no - it doesn't have an adaptive transmission / engine control design. no it doesn't have VSC.
i like it! if it were a manual, i'd like it better.
yes - hesitating at HW speeds when trying the change lanes or merge, or when slowing and re-applying the throttle like a light that just changes to green, or making a left-hand turn - we are talking about some vastly different scenarios aren't we?
where i definitely disagree with you, and i agree with another poster is the AT is supposed to be designed to shift at the proper points and eliminate the need to drop it to a lower gear manually. if it can't do that properly - it's flawed isn't it?
if there weren't enough human factors problems with the hesitation itself, you propose people actually get used to manually shifting their ATs under a number of scenarios. for those of us comming from manual trans, i tend to agree that it might help under certain scenarios (when you need power for passing, or going up a steep incline), but no - for the general public, i can't see that being workable. talk about the potential for more problems...
it's so easy to say - people - adapt to the automation. no no no. proper design dictates that you don't compensate for automation. automation facilitates and augments your abilities...now = should it be adaptive. hmmm - evidently - making one of these things truely "smart" is challenging.
maybe a manufacturer will bring us a lower-tech solution. a vote again for the manual transmission.
Is there anything in the owner's manual, in the auto trans department, that talks about how to shift or when to shift or ????
Pilot, if I were to sit down and write up all the good things I can say about my 2001 RX300 I would likely be busy for weeks and weeks. But most of what I would say has already been published by Lexus or some automotive magazine's "shill" writer, and is readily available for public consumption.
What we have here at Edmunds is a place where we can freely converse about stuff that the manufacturers, mostly, do not wish to have see the light of day. And it's perfectly okay for you to cast a disbelieving eye on those of us who sometimes raise matters that discredit the marque or marques.
But please keep in mind that absent that very "first" person being willing to speak up about a potential flaw or problem there would be no way to "filter" the true from the false in the long term. So think of this, Edmunds, as a gathering place, conference table, for folks to gather around and jointly and openly discuss seeming problems or design flaws. Out of these discussions, certainly some of the seeming problems will be found wanting, while others, the engine sludge case in point, will be determined to be well founded.
Do you really want to discourage that "first" person from coming forth and telling their tale by continually naysaying anything and everything adverse to teh marque?
I'm not into discouraging anyone from coming forth and telling their tale.
That's a matter of record.
I am, however, into using this forum for what it's intended--something along the lines of your analogy: "a gathering place, conference table, for folks to gather around and jointly and openly discuss seeming problems."
A few aren't here for that. I think you know it.
Those few don't seek a balanced approach to the issue.
Back on topic youse guys.
Mr. Shiftright's overdrive ideas aren't that far off, IMO.
Way back when (remember?) I was rudely invited to leave when I spoke of asking a friend who runs a highly regarded Tranny Repair Shop about the hesitation issue.
Never did get a chance to finish, because "the few" jumped in with the usual propaganda and I just backed off.
One of his unforgettable comments was that a five speed tranny is a different animal, and requires getting used to.
I distinctly remember him saying hesitation at low speeds and heavy accelleration is not unusual.
User777, please note he stated they all do it to a greater or lesser degree and if you look around you'll see that's correct!. Other makes do report the same characteristic.
Upshifts/downshifts, by their nature in those trannys just take longer.
Shifty, you'se closer than you think, I think.
You think?
what are the other makes reporting the same characteristic?
The reason I brought up the O/D issue is because I'm wondering if the engine isn't sometimes just bogging down in 5th gear. It has nothing to do with the gas or throttle--the engine just cannot pull 5th gear at that low speed.
This leads me to think that if there is a 'defect' it is in how the transmission senses that the engine can't pull the gear. I wonder how that trans gets the message to downshift? If I were Toyota that's where I'd look.
another interesting experiment would be to NEVER have the transmission in 5th for a week or two. If the hesitation goes away, then that's your area of study right there--the 5 to 4 downshift.
One gets used to it after a while!!
Re your question about other makes, try Volvo for starters, then if you're still convinced Toyota's the sole sufferer, I'll point you to a few more.
Also, read my "Highly regarded Tranny Shop" spiel again please.
Note my friend said "They all do it.....To a *greater or lesser* degree."
That might explain why some notice it and others don't.
It also points to the (already well known) fact that it tends to occur most noticeably when people stomp on the throttle at low speeds.
BTW, my friend's "Highly regarded Tranny Shop" must have something going for it. Every auto franchise in the county brings its tranny work to him, PLUS his shops (he has two) are the ONLY Rolls Royce certified repair depots in SW Ontario, Michigan, Ohio, and Indiana.
You'll never see more Rolls Royces in one place wherever you might be.
So it is, indeed, "highly regarded."
isn't that what we are primarily debating with respect to one particular manufacturer's products (realizing that this forum is for hesitation of any form, all makes - we were forced to this situation by another host remember)?
comment: you're covering ground wwest speculated on many moons ago. at least at that time, he was giving posters with the issue something to think about, research, and discuss with their dealer, when the dealer spoke the words of wisdom: "this is normal - they all do it".
we've had a report of a potential sienna purchaser (another forum) take out two new vehicles sitting side-by-side: one has hesitation which is detectible, and another doesn't.
*if* as some speculate there is a connection with the "learning algorithm" which is employed in the vehicle, then hmmm - maybe that is at root cause. maybe they are too smart for their own good.
i have indicated what i would do to research and attempt to capture objective, quantitative data in a vehicle with the hesitation. with a laptop and a couple of hundred dollars, it seems one of these ODB-II readers should be able to capture the phenomenon, and no arbitrator, dealer or manufacturer rep is going to be able to debate that.
geesh shifty - isn't there a few geeks on staff willing to foot the bill for a cheap reader and instrument one of these cars?
again - wwest has speculated on the attempt by manufacturers to achieve higher gas mileage with their approach to programming of the shift points in an adaptive manner.
others have argued for resetting the learning by removing power from the battery. that doesn't seem to have fixed matters.
as i mentioned before - this automation is complex, and doesn't provide a good mental model of what is going on to the user so we can understand what is supposed to happen or predict how it will behave.
pilot130: where was the sarcasm in the post? i can't follow how you conclude this. remember, you claimed (if i'm not mistaken) that your expert knew the root cause and how to take care of it. if that were true, if he knew something a certain manufacturer didn't then wouldn't you think their designers would consult the expert? remember i asked what was the special insight which he/she possessed? and you never posted it - you claimed you were being attacked by some poster... you are NOW providing some supporting credentials as to the observation and opinions of the individual (which is good), but you STILL haven't provided anything workable or that improves on what has been posted... your quote from this expert is "they all do it to a greater or lesser degree".
really - if you dish it, you have to be able to take it, so it's good to know you can handle it. look - were just trying to make some sense of this and help people aren't we?
question: does "lesser" include no hesitation? i would presume it does. i've got a non-DBW 5-speed minivan that doesn't hesitate. when i ask for power - i get it. it isn't confused at low speeds as to what gear it should be in, it doesn't lug the engine. there are others out there with vehicles from different manufacturers with DBW technology that aren't experiencing hesitation. let me clarify that - all we know is they aren't reporting the hesitation which we are debating.
so what is going on? fair question isn't it?
i apologize now for using all this bandwidth. i know there are people wanting to know what can be done to solve the problem.
http://www.wnep.com/global/story.asp?s=1830517&ClientType=Print
Unfortunately many of the engine hesitation complaints with Hyundai, Jeep Wrangler, Suburban, etc. are being reported in competing automotive forums, so I can't post them.
But it does seem that Toyota is not the only automaker having these problems. I have no idea how related they are to other carmaker's problems.
Let's see - down thru the years Toyota has had 3-speed automatics, then 4-speed automatics. Thru that period, I never heard about anything like this hesitation issue. Does anyone recall a major hesitation with Toyota transmissions until the 5-speed? I don't think so - and even then, not until DBW and VSC were grafted on top of it. Does anyone with a V-6, WITHOUT VSC or DBW, but WITH the 5-speed auto, have any issues or comments?
In my view, as an engineer, this is all the result of "pushed-to-market" technology. They'll get it right, (or at least much better) eventually. The "Next Generation" VSC will come out, hopefully soon, and this will all fade into history. Until then, we can all develop theories and suppose one thing or another, but the ball's in Toyota's court to address this issue. Nothing we do will make much difference, short of stopping buying these vehicles. That's the way capitalism works. Those that already have the problem, and continue to push the issues with Manufacturer and Dealer, have my eternal gratitude and sympathy. But for the grace of Edmunds and its posters, there go I.
It'll be interesting if anyone can get a Hesitater into Shifty's hands, and let him drive it.
I appreciate the heck out of my Toyota Highlander. It's a great ride, as I've stated many times. But if we all let the manufacturer off the hook, and just adapt ourselves to technology that doesn't work as intended, we're all going to end up servicing our vehicles every few weeks - think Windows XP SP2. (Or Windows Millennium Edition). I'd rather manufacturers simply test their products, and release them when they work. And then either fix them or buy them back if they don't. We're not there yet. But I'm sticking around.
My car (Porsche) is quite powerful but if I slam the gas in 5th gear at 1,800 rpm the car simply bucks and hesitates. Now I know better than to do this but maybe a 5-speed automatic doesn't know better for some reason.
If as people suggest it takes a beat or two to unlock the torque converter (I don't know I haven't investigated any of this), then sure I can see a big opportunity for the car to fall flat on its face at low rpm when attempting a downshift from 5th (overdrive).
Drive any auto trans car for awhile. When you are at, say, 35 mph in top gear, be it 3rd, 4th or 5th, depending on the transmission - then you punch it, it downshifts to the lowest gear it can without over-revving the engine. And then proceeds to up-shift at or close to red-line.
Shifty - you've gotta get out more. Or at least have an auto-trans car in your stable (and drive it!) to prepare yourself for this Forum. (Imagine a tongue-in-cheek Edmunds blue-car emoticon here).
Maybe the only difference we have is that I'm saying that IF you are in 5th OD at a low speed (driving an automatic) and IF it doesn't downshift right away, you're going to bog with that tall overdrive gear, and perhaps the bog itself drops engine vacuum and screws up the downshift signal to go to 4th, 3rd or whatever.
I wish I knew how exactly the Toyota 5th speed knows to downshift, that would help me speculate. Is it totally electronic or is engine vacuum involved I wonder.
You brought back memories of learning to drive in my brother's 50 Ford. I could start it in 3rd gear!!!
My 4-speed T65E has no problems with picking the right gearing whether it's turning the engine slowly in 3rd or 4th and I step on it. I wonder if the lag is a combination of engine control and the transmission having been over-engineered to maximize economy so it's not quick to handle getting to the correct gearing when called upon because it's in too high a gear...
2014 Malibu 2LT, 2015 Cruze 2LT,
Okay, first, how many, if any, RX330 owners have experienced the "bumped from behind" symptom just before coming to a full stop, or the "slingshot effect" during coastdown, throttle closed, from say 30-50MPH?
If the answer is none then just ignore the following.
My 2001 AWD RX300 exhibits both of the above symptoms. The seat of the pants "feeling" of both of these symptoms is as if the clutch were just disengaged with a manual transmission. I have two theories as to why this is happening and neither of them, or one, or even both, may be the actual case. Theory one is that the transmission is being upshifted to reduce engine braking, allowing the vehicle to coast farther and thereby increase fuel economy. Theory two is that the vehicle is being upshifted just before coming to a stop to prevent potential loss of control due to engine braking at the front wheels on a possibly icy roadbed.
Think about this. If you were driving a FWD vehicle with a clutch would you EVER downshift to use engine braking on an icy roadbed?
Yet don't we fully expect a FWD's automatic transaxle to downshift into first as we slow to a stop.
Personally I think the designers have made a wise choice here, they have no way of detecting the roadbed conditions as you come to a stop so the best action on their part is to write the firmware to provide an upshift ("disengage the clutch to prevent loss of directional control" ) when slowing to a final stop and only shift down into first once the vehicle is FULLY stopped.
As I have already said, if your RX330 doesn't have the above symptoms then it is needless to read farther.
But if the firmware in the RX330 engine and transaxle ECU is doing the same thing as my RX300 then I can see how that might lead to some serious indecisiveness on the part of the firmware.
The firmware initially detects a coastdown situation, brakes on or not, but the gas pedal fully released, so it begins the upshift sequence. Now you start "dithering" the gas pedal because you're being indecisive about whether or not you can accelerate quickly enough to safely merge into the opening in the adjacent freeway lane.
According to the firmware the transaxle hasn't yet completed the upshift sequence and now you're giving it mixed signals, dithering the gas pedal, about what it should do next.
According to the shop manual the transaxle servo system's feedback, the way it tells when and what gear ratio the transaxle is actually in, is via comparing the transaxle's input shaft speed with/against the output shaft speed. In other words it commands a certain gear ratio via electrically actuating the appropriate solenoids and only knows that if the commanded shift is complete when/if the computed input/output ratio indicates that it is.
And what if your own indecisiveness, your "dithering" of the gas pedal, is confusing the firmware with regards how far to downshift? Remember that once the ECU commands a downshift, say into 3rd, that "shift" must be verified to be completed via the input/output computation. So the shift into 3rd has just begun and you relax the pressure on the gas pedal ever so slightly.
Oops, the firmware now decides you should only downshift into 4th.
Oh, my RX300 only has three forward gears plus OD so there is not as much "opportunity" for the firmware to be indecisive!
it's funny - i keep hoping someone is going to tell us authoritatively how these things are actually designed to work and where the issue really resides.
we can't start a pool can we? how about a forum-specific survey? can the edmunds IT people pull off one of those?
specifically I'd like to know what causes the 5 speed automatic to shift from 5 to 4. Is it vacuum, completely digital or a combination of both?
Purely for this EPA Test reason, I think Toyota takes it one step farther - the don't shift to 5th, they put it in neutral. This would account for the "slingshot" effect, and the added indecision of the trans. It's one thing to go from 5th to 3rd (or to 2nd or even 1st) - it's another, more risky thing to downshift from neutral. Recall that, after starting the vehicle in Park (which is really Neutral plus parking pawl lock), you have to depress the brake in order to shift. Well, we can't do that while coasting, so the ECU has to check a few things out before putting it in any gear, that it wouldn't have to do if were still in gear.
This isn't "neutral" like a manual trans, which is where you want to be when rev-matching during heel-and-toe - there, the clutch is connected and you can speed up the gears. Here, all the clutches are not connected - you gotta check out real road speed so that you don't burn the clutch you decide to close. Maybe someday the rev-matching can be handled by the microprocessor as well. The twin-clutch systems that BMW and VW have do this.
This also fits with the concepts that others have posted, about Toyota first saying the 5-speed trans fluid needed no changing - then telling us that it DOES need to be changed, and quite frequently. Anybody recall that post? I don't have the details...
Just my 2 cents.
It's the way I've always hoped discussion on this hesitation issue would be, and it was great to see.
Keep it up.
For User777. Way back when I spoke of my friend with the Tranny Shop, I don't think I said he knew what the problem was, that is, something Toyota didn't know and he had discovered.
I believe I said he had a fix for the characteristic--a solution--and he was speaking at the time about the problem in a general context where it's typical of all auto 5 speed 4 by 4's.
Tell you what.
I'll be back in The Great White North around the end of the month and will make a point of revisiting the issue with my friend, and get back to you with his thoughts on a remedy.
In the meantime, what you guys are doing right now is a heck of a lot more helpful and productive than just waving the flag every day.
Congrats.
you write:
Every automatic American car I've ever driven upshifts while coasting.
did you mean to write "upshift" (move to a higher gear)?
now i'm confused.
i wrote what i wrote because it follows - if the transmission expert you know has a solution for the "characteristic", "behavior", "problem" - he knows what the problem is.
ok - this is not meant to be sarcastic: i don't know what the problem is - and i'm no expert - but obviously one way to solve it is to move to another vehicle (which some people have done). another "solution" is to replace the design with another design which doesn't have the behavior, but that isn't a realistic solution for a consumer.
only he knows if he was advocating moving to another vehicle, replacing the transmission / ecu, disconnecting something, replacing something, reprogramming something, etc.
sure, when you get back, if you could ask him what he'd do, it would be good to know.