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Engine Hesitation (All makes/models)
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2014 Malibu 2LT, 2015 Cruze 2LT,
I'd bet that the LAST thing this guy wants to do in his spare time is fix transmissions.
It's a slow day on this thread - can you tell?
i drive a honda v6 5spd AT. its not DBW. if I let my foot off the accelerator, you're telling me it is actually upshifting and when i re-apply the gas, it immediately downshifts into the proper gear to minimize the transient and smoothly apply power. this is when going on a flat.
so - when going downhill, might it actually downshift to perform engine breaking?
this AT stuff is making the manuals seem so simple.
Most transmissions don't automatically do into lower gear downhill. Sometimes, my 4-speed auto / 4-cylinder Highlander does. Yours might too. Just watch your tach, and you can tell what gear you're in.
Believe me, I'd rather have a Highlander with a manual trans. It's just that they don't make 'em.
"First, owners of other Toyota and Lexus models called to say their cars had the same problems. Then letters came in from owners of Mercedes Benz products. Then calls to Consumer Reports revealed that Audi A6 2.7T, Audi allroad, and the Mazda 6 equipped with a V-6 engine, as well as the Volkswagen Jetta 1.8 T suffered from the same malady.
Finally, checks into National Highway Traffic Safety Administration records revealed BMW’s 3 Series, Ford Explorers and Escapes, and the Dodge Durango 4 x 4, all 2004 models, also had problems with hesitation that caused harrowing experiences for their owners.
What’s going on here?
David Champion, senior director of Consumer Reports’ Auto Test Center in Connecticut said the problem involves the transmission gearbox electronic control unit and the engine management control unit in these cars.
“It’s the way in which the transmission gearbox electronic control unit talks to the engine management control unit. The integration of the two systems will allow the transmission to function in the right gear and the engine to provide the power instantaneously in a smooth fashion,” he said.
He added, “When you accelerate, the gearbox may change down a gear or find the right gear, and to make the transmission takeoff a smooth one, it retards the ignition to reduce engine power. Unfortunately, while the control unit works out what it is supposed to be doing, you’re putting your foot on the accelerator. It can lose its way and doesn't energize the engine and transmission quickly enough.”
Unfortunately, the problem apparently has stumped engineers for some car companies, which are feverishly trying to find solutions. At Lexus, according to a Toyota spokesman, a “fix” that they hoped would solve the problem does not do so, and they are now looking for other solutions."
NOT!
Well, maybe.
But only because for the past "many years" FWD vehicles have dominated the market.
Engine compression braking on a FWD, or front torque biased AWD, can be extremely hazardous under the right (wrong??) roadbed conditions. I would not hesitate to downshift a RWD and "feather" the clutch (assumption=stick) to slow on a slippery surface, but to do so in a FWD vehicle would be unduly risking one's life.
There are LOTS of RWD, and rear biased AWD/4WD, vehicles with automatics that remain in the same gear when you lift the gas pedal. Try either the BMW X3 or X5 for instance, lots of engine compression braking when you let off the gas and INSTANT response when you re-apply gas.
I am absolutely behind, all for, the designers writing the control firmware to reduce engine compression braking on FWD vehicles as a safety measure. But having it result in "engine hesitation" and the dangers therefrom, is another matter altogether.
In the Camry board, two days ago, you told the folks this "Engine Hesitation-all Makes" issue concerns only Toyota/Lexus.
You also highlighted those Pittsburg Post Gazette web addresses again--how many times now. 10, 12, 15?.
You stated in that thread this one was erroniously entitled "All Makes", and only applies to Toyota/Lexus.
Your post, Camry Thread, April 8, says quote: "There is a board here at Edmunds dedicated to Hesitation (inappropriately titled "Engine Hesitation") but site is almost 100% discussion of hesitation/lag upon acceleration in Toyota/Lexus line)"
Today, you post the rest of your earlier Hammond article here which talks about other makes having the same characteristic.
I wonder:
(1)Why didn't you quote the rest of the Hammond article about other makes, the first time around--and in all the other threads you post it in?
(2)Are you now saying you agree the characteristic is present in other makes too?
(3)Why do you tell others in another thread this thread is innappropriately titled?.
With mixed messages like that, it casts doubt what your motives really are in this issue.
It brings to mind the style of hyperbole used in the past by the infamous Charlene Blake, and I'm sure you don't want people to think that of you.
Bosch, Denso, who?
Don't shoot them yet - let 'em fix the ones they've already sold.
Sort of a form of multi-tasking, even while charged with an earlier task, it kept a lookout for new assignments, dropped the old task and assumed the new one.
The new electronic transmission's mechanical design just simply doesn't allow the firmware to be multi-tasking even though it, the firmware, clearly could be. The problem is that the shifting sequence, once initiated by the ECU's energization of the proper solenoids, runs in "open loop" mode. No possibility for multi-tasking since the ECU doesn't "know" where the transmission is in the commanded shifting process until it has fully completed the previously commanded sequence.
And we know that it takes something on the order of one second to shift from neutral to drive, probably 1st gear. So if the firmware commands the upshift sequence due to your closing the throttle and then you suddenly change your mind the ECU must wait for the upshift to be complete before it begins the downshift you just initiated.
There will be no fix unless the coastdown upshift sequences can be eliminated and that will not happen unless the EPA and CARB waive the regulations governing modifying the "installed" base.
Many millions of automatic transmission were made that had no electrical connections at all, save for the back-up light. Pure hydraulic. Mostly, they worked great, for many more miles than current transmissions do. The electronics were easy to do at first, as they played within themselves. But now...
And all this stuff about "they can't solve it" - it's not a question of if, it's a question of when. There's no inherent reason that the MicroP couldn't keep on computing the next gear, even while it's deciding the current shift. Just a matter of processing power (read=$) and the programming.
In the field I work in, my Company is currently the industry leader in processing speed and power, using 66mHz processors. That's more than enough for the product we make - but this goes to show that individual people, working in teams, design products to meet a market, and to a price point (that's what Marketing people do...), to achieve a planned market position. And sometimes, it doesn't work so well on the first go-around. Which, if you're making only 10 a week, is not a big deal. But if you make only 5,000 a week (that's less that the number of V-6 5-speed auto powertrains a week), there is a temptation to save $20 a vehicle. Because that's $100k a week in bottom-line dollars saved. Which is like another $1million a week in top-line (sales) dollars. The cost of these micro processors have come down a lot in recent years, as PC's reached for the stars to multi-gigabit processors, and pushed down the cost of lesser-spec'd devices. Sometimes, the engineer specs a processor to do the job they thought it should be, and the program code grows, and becomes more than the processor can handle in the real-world time frame. Which no one can test for, by release date.
So what's the point? Knowing this, it's clear - all Toyota needs to do to make their transmissions behave is to budget more money for their CPU's (hardware) and programmers' time (softare). That, plus time, will give us a product that does the job. It's not like they don't have money to invest...
The sooner Toyota realizes that they need to do something about this issue, the sooner that process will begin. The more they fear the impact on future sales, the more time, effort, and money they'll put into it. That's the beauty of this Forum. You can be heard.
Here is what I posted on the Camry board in response to posts by others regarding hesitation:
" ...There is a board here at Edmunds dedicated to hesitation (inappropriately titled "Engine Hesitation" but site is almost 100% discussion of hesitation/lag upon acceleration in Toyota/Lexus line), so if you wish to discuss with others, you can go to http://townhall-talk.edmunds.com/direct/view/.ef4cdbd/570 "
So, you see how my words were totally twisted around? We discussed earlier on this site that the word "Engine" in the title was not really applicable to this problem in Toyota's.
This Hesitation site HAS been nearly 100% discussion of the hesitation/lag in the Toyota/Lexus line, but as you said, wwest, this site grew out of a discussion in the Highlander forum that was moved here, so this would be expected.
Regarding your post #590 dealing with Audi's and drive by wire:
http://www.audiusa.com/lexicon/0,3864,categoryId-2_,00.html#120
"From the Audi Lexicon:
Drive-by-wire throttle
Like modern aircraft, the accelerator on some Audi models works on the "drive-by-wire" principle. Drive-by-wire throttle interprets pedal input from the driver and automatically adjusts the throttle, turbo boost and ignition timing to deliver..."
--------------
Also, referencing your post #590 and regarding two new vehicles on dealer's lot, one having problem, the other not. Yes, it does stand to reason that one that has been test driven more frequently may have had the opportunity to learn driving habits. I have read several reports of people getting a temporary correction of the problem by disconnecting then reconnecting the battery. Something to think about... if a new vehicle is experiencing hesitation, couldn't the dealership do the battery disconnect/reconnect to temporarily erase the problem so that it is not apparent on test drives?
Anyone here with the problem tried the disconnecting battery trick? How did it work?
#7562 of 7645 Hesitation flaw revisited by coastdriver Mar 08, 2005 (3:56 pm)
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I tried the "battery disconnect solution." Unhooked both the positive and negative battery cables, and let the car sit for 2 hours.
Seems pretty stupid, but what the heck.
Well, my new Camry is a stubborn girl! She just laughed at me, and continues on her merry way of hesitating, jerking, pausing, and going into limbo while trying to decide what gear to use.
And to think, I even splurged and gave her a nice healthy swig of Premium fuel for her tummy! She just hicupped, belched, farted, and smiled at me and thanked me for the shot of whiskey.
Last seen staggering down the 405 freeway, southbound.....
I give up. Just live with it. In my next life, I'll buy an Infinity, a BMW, or a Mercedes... or an old '65 Chevy pickup.
#2948 of 3193 Hesitation- A fix? by autoguy1 Feb 27, 2005 (9:36 pm)
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I'm copying & pasting something I posted over at Sienna's forum.
Something happened to me I'd like to share. A member of the "other" forum said this could help and I'm backing him up.
Recently, I killed the battery in my Sienna (my fault) and everything was drained. In doing so, I think the Car's ECU was completely erased. The car was jump started and everything was fine.
Now, beginning, my throttle was mush. You press the first area of the pedal = nothing. Now, after the battery was drained and everything reset, I can now tap the pedal ever so slightly and the engine responds immediately. I don't need to press it down more for it to start but now just tapping it makes it move.
This happened out of an accident and the hesitation was not much of a problem but now the throttle feel is fantastic. I feel like I can manage it now.
The other member didn't drain the battery but disconnected it via negative terminal and let it like that for about 5 mins (I was stuck with no battery for about an hour). He then reconnected it and started the car but strongly noted that you don't touch the throttle at all. DO NOT TOUCH IT WHILE YOU START THE CAR.
Go for a regular drive. See if everything is better. Curiously enough, like I mentioned, my throttle is very responsive and not dead like before.
And I'd like to note that the tranny itself is perfectly fine. It's the poorly done throttle causing a problem.
I think I might have you beat...
My company BUILDS processors that run at a maximum of 36Mhz, but mostly our customers run them at 9Mhz (PDP-11/93-94 equivalent), or even lower in the case of the HP-2115.
But my desertation wasn't about processing power or even the ability for the software to be multi-tasking. The problem, first, is a mechanical one, second, a lack of intermediate feedback, and lastly, the CAFE and CARB regulations.
Once the ECU energizes the correct solenoids for an upshift (ANY shift) it has no way to determine, other than maybe a time delay, the state(s) of the transmission shifting sequence until the input/output rotational ratio indicates the shift has completed and "settled".
So if even if you suddenly FLOOR the gas pedal just as a shift begins, or during a shift sequence, the ECU cannot command a new shift sequence until the previous one has "run" to completion.
Issuing a new shift command before confirming the previous one has completed might very well result in the transmission being temporarily in TWO gears, possibly for only a few milliseconds, but enough to prematurely destroy, wear out, the clutches involved.
I strongly suspect that's why the pre-04 RX300 transmissions are incurring an unusually high low mileage failure rate. That's likely also why Lexus is now recommending the transaxle fluid be flushed and replenished every 15,000 miles. The debris from the clutch wear is contaminating the fluid to such a high level that it is not fully functional.
For the 04 and later RX330 they went to DBW so the onset of engine torque could be delayed in the circumstance wherein the ECU had to wait for the previous shift to complete before even beginning the downshift you NEED.
That said, personally, the hesitation is a deal killer for me. But I must admit, while I don't know how pervasive the problem is, it does seem that many people are not noticing it. I am not sure if that means that it is not present, it is present but the delay is not significant enough to be noticed, or it is present and noticeable but people just don't care (writing it off as an anamoly of the car). I do feel that when present with a 1 - 2 second delay, it is a safety hazard, so that is why it is a deal killer for me. For me, I am taking a wait and see position -- wait to see what Lexus/Toyota comes up with for a fix. Right now, they have said they are looking into it and the NHTSA is determining whether to open an investigation - I want to see what comes out of it.
Until a FINAL solution is announced, which may come in the form of a redesigned transmission in the 06 models.
Nothing really explains this, though - why did/does the 4-speed auto not have this issue? And, why does Honda's 5-speed auto (also DBW) not have this issue? There's a lot yet to be known about this problem. I'm still waiting for the VSC to be implicated by Toyota. This is an important safety feature, but it's also completely dependent on the processor's ability to get thru lots of lines of code, quickly. If it's like the things I work on, the "safety" parts of the program have priority, and have low activation thresholds. This translates to a hardware requirement for more memory, faster processing, and better programming (all of these things increase cost - important when you consider how many of hundreds of thousands of these Toyota makes every years). Multiple processors, operating in parallel, make this even more of a challenge.
In any case, I'll bet that the people that USE processors are more familiar with software than the people that MAKE processors.
I'm taking wwest's approach - wait until the '06's come out, and re-test. Right now, my '02 is running strong enough to get me thru the next six months at least.
2014 Malibu 2LT, 2015 Cruze 2LT,
It's more likely the valve body hydraulic sequencing along with the actual time it takes to release the clutches from the previous gear ratio, give them time to actually fully release, hydraulic pressure to bleed off, and then "order" the proper set of clutches for the new gear ratio to be engaged, pressurized, and the wait for them to be fully engaged.
Think of the time it takes with a stick shift, assuming you want your manual clutch to have a long life.
Get off the gas, and disengage the clutch (unlock the torque converter) take the shifter out of the previous gear (release the hydraulic pressure on the clutches for the previous gear and wait for the "return" springs to force them open.), slide the stick into the new gear (pressurize the clutches for the new gear ratio, and wait for them to engage), release the clutch pedal and apply appropriate pressure to the gas pedal (heavy gas pedal pressure, or closed throttle, leave the torque converter unlocked. Gas pedal positioned for cruising, lockup the torque converter).
"-Why did/does the 4-speed auto not have this issue..."
I have argued that it actually does.
But in a different "form".
I have no doubts whatsoever that the transaxle in my RX upshifts if the throttle is fully closed during highway coastdown and just before coming to a full stop. When it does and I re-apply pressure to the gas pedal it must now downshift.
The transaxles in the previous model, the RX300, seem to be failing prematurely at an unusually high rate. I have reported that the transaxle fluid in my RX was burnt and dirty looking at 38k miles and apparently Lexus has revised the recommended maintenance schedule from NONE to every 15,000 miles to address some here-to-fore unknown flawed operational aspect of these transaxles.
My RX has a mechanical throttle connection so the throttle valve cannot be closed during a transaxle shift sequence. Can Lexus temporarily "detorque" the engine some during the shift sequence?
Stop the ignition ? = RAW gas & air mixture into the exhaust stack and catalytic converter.
Disable the fuel injector power? = PURE oxygen to the exhaust stack and catalytic converter.
Considering the EPA's and CARB constantly changing, updated, emission standards are either of the above choices viable. What are their long term effects on the oxygen sensor and/or the catalytic converter.
Suppose the firmware in my RX series, with an engine that cannot be dethrottled for 1 to 2 seconds, doesn't have an embedded wait delay to be sure the previous gear ratio clutches are fully released before engaging the next "set". That would result in BURNT clutch frictional surfaces, burnt and "dirty" looking fluid, and eventual failure of those clutches.
What's the most economical fix to prevent premature transaxle failures in the newer models?
DBW.
Wrong!!!!!!!
thanks!
My 2004 Sienna does this. Its EPA ratings are 27/19 hwy/city.I understand that the problem has been reduced or eliminated in the 2005's. And guess what - their EPA ratings are 26/19. The transmission in the 2005's has a different part number, but same ratios, mounting points, and everything else. Engine is unchanged.
So the reason Toyota won't be coming up with a fix for the 2004's, is because they can't do it and still remain in their EPA estimates of 27/19. There are no mechanical reasons why the tranny can't downshift quickly. It's just being told not to by the computer. And that's not going to change, until someone figures out an aftermarket way to reprogram them. Toyota is forbidden by law from modifying their cars in such a way that will lower the EPA fuel economy rating.
Totally WRONG.
There are a few who desperately want us all to believe that, but it is just flat not true!
Sorry, but that's the end of the story.
And I don't think it has anything to do with any "reluctance" to have the system downshift. I think what it really is is that the transaxle is caught in the upshifting sequence when you ask for downshift and it cannot begin the downshift sequence until the upshift has completed.
And those "upshifts" are what really impact the fuel economy and the emissions standards. Remember what OD is all about?
The slower the engine turns the lower the frictional losses, just as long as it still produces enough torque to maintain a constant speed on level terrain. So the ECU is programmed to upshift the transaxle at each and every opportunity.
And I still suspect that it is the drivers who "dither" the throttle, indecisiveness about "can I merge successfully or not", that most often encounter the hesitation symptom.
When I was speaking of the 4-speed auto, I was referring to the behavior of mine. No hesitation at all - a really great design. And I haven't read a posting in this forum about a hesitating 4-speed auto. Now I suppose the smart thing to do is to change the fluid in it soon, and try not to worry about it all the while I have it.
Me, I'd like more choices of vehicles with manual transmissions, please!
Of course I am still following the discussion and throwing in my opinion. I think all v6 5speed autos have the problem. I think it varies a bit from car to car but they all do it. during my arbitration I argued with the Toyota tech rep. that some cars must be alot worse than others. He said that they all do it and I would not find a different Camry that would be any better. I am really thinking that driving style or habits have more to do with the severity of the problems for different individuals.
I think if I drove a car who's owner was not complaining I would still feel it. i know this sound odd and some of you will disagree but it just bothers some people alot more than others. If enough people don't like it it's a problem.
How do you feel you are any better off? I really wonder if you are telling the whole story just as it happened. I suspect there a couple of posters who seem to only be interested in reminding everyone of bad news about Toyota. Is your reason the same?
Enjoying the ride is what a couple of million drivers are doing, and it serves no good purpose to keep trying to convince them they should not be.
You have twisted the facts to suit your purpose. There is no wide spread deficiency.
I have a 2003 Highlander V6 2wd, 25,000 miles and have loved it. Started thinking about adding a new Highlander to the family, as my wife also liked driving the Highlander, rather than her 2003 Camry SE 4cyl 4 spd automatic (DBW, by the way). She liked the Camry just fine, but prefered the higher seating and visibility of the Highlander.
After reading MUCH on the internet about this ...uhmmm....hmmm...issue, I drove MANY examples of the Toyota/Lexus V6 5psd automatic DBW vehicles. Probably 20-25 different examples, both used and new. I tried to simulate the conditions that apparently create this hesitation...to no avail, so my conclusion was that it is not a problem for me. Repeat, for me.
Fast forward to today....I now have a new 2005 Highlander Limited V6 5spd automatic DBW in my garage for 3 weeks and about 1,500 miles. It does shift differently than our 2003 Highlander, (it IS a different transmission, after all) but is it deficient? Is it defective? I don't believe it is in my mind...or my seat of the pants.
Perhaps it is my driving style, or my expectations. I can feel something that others have called "slingshot" as I approach a stop, but it just feels to me like the trany is downshifting (perhaps its the unlocking of the torque converter that is felt?)... At any rate, this is not an annoyance for me, as my new Highlander gets consistantly 10% or more better gas mileage than my 2003, and has more power. This is my experience, not based on EPA numbers.
BTW, Our 2003 Camry SE is now being driven by our daughter. It had a comment in the owners manual regarding the trans... I don't have it in front of me now to quote exactly, but something relating to the trans downshifting while braking going down hill to aid in the slowong of the vehicle. I noticed it while driving the Camry, but my wife didn't even notice it. Same vehicle. I notice that same thing happening in pour 2005 Highlander, but not in the 2003 Highlander. To my knowlegde, no one her has mentioned that. It is not noted in the owners manual for the 2005 Highlander.
thank you for this wonderful forum!
respectfully, Jeff
As for my Acura purchase. I was actually looking at alot of different cars new and low mileage used. I happened to run across this one owner TL local car with complete service history and 100,000 mile acura extended transmission warranty for a price that makes it a fairly low risk (the car has 65,000miles and I paid $11,000). This is not the answer for everybody but I feel good about it.
Same thing with a five speed automatic. If you try hard enough you can duplicate it in a manual.
That is what is happening to the people who are complaining. Hesitation with those conditions is a normal reaction. It is not a problem unless you want it to be.
kraft...you just said in one sentence what I took 10 minutes to write! Nice.
This sounds like another poster here who says the same thing when he posts carefuly chosen snippets of bad news every day--"I am trying to help people".
The only *benefit* I can see is this is a way of trying to scare people to not buy a Toyota. It's like telling people they have 1 chance in 5 of getting terminal cancer. It is *helpful* if you want to look at it that way. Kind of dumb if you ask me. The only person getting any benefit is the person telling the bad news.