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Engine Hesitation (All makes/models)
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Perhaps that notification should appear in a broad cross section of other makes and models which contain hesitation reports and discussions. There are many, ie, Volvo, Mazda, Subaru, Honda, Kia, Hyundai, Ford GM, Chrysler, Land Rover......
It certainly isn't unique to just Toyota Highlander and Lexus ES300.
Another good prospect is the "Transmission Trauma" forum. A number of reports in other makes appear there too.
Evidently it's not an uncommon issue, especially with 4 or All Wheel Drive vehicles.
Pilot-- I see what you're saying here but I don't think it's going to work. "Hesitation" is a very generalized term, much like the word "noise" or "clunking sound". One could probably apply some form of hesitation problem to every car made in some sense or another. The reason "Transmission Traumas" works as a forum is because, I think anyway, that the word "transmission" focuses it to one component that has a lot less gadgetry controlling it than an engine. And even there we get all kinds of problems that are not transmission related and have to be referred to other forums.
Shifty the Host
However, I did spend a whole bunch of time going through other forums in the past three or four days, searching for specific references to tranny hesitation.
I found quite a few mentions of, and discussions about, similar hesitation phenomena being talked about here.
I'm also sure that eventually, those concerned about the issue in any make or model will eventually find their way here with or without encouragement. Going around to other forums with "reminders" really isn't really necessary, nor does it serve much purpose.
I was actually trying to make a subtle point that the issue isn't confined to just one brand/model, and trying not to be branded as offensive while doing so.
and there's a need for a forum like this.
but...i thought, when we were moved from the Highlander Forum, that predominately we were talking about DBW-based (e-Throttle) systems.
don't all the Toyota models where people are relating their experience with hesitation (when approaching lights that change or merging), e-Throttle based?
anyway, how do we know if it's in the engine or transmission, neither, or both?
hmmm. maybe the forum should be titled even more generically: "Hesitation".
Also, thanks Shifty. That piece of advice about advanced searches will make Edmunds a lot more useful to me.
I don't really disagree...
But the hesitation descriptions(***) for the Toyota and Lexus FWD or front biased vehicles all seem to fit the same "template". So in this case I think these users symptoms are unique to this marque's FWD and front biased AWD vehicles.
***
1. Hesitation with quick (1/2?) throttle application just before coming to a full stop.
2. Hesitation with quick (1/2?) throttle application from coastdown condition.
3. Seemingly more serious hesitation in both above instances with serious direction inputs simultaneously.
I came across this one by doing a Google search.
Cars.com Road test and owner survey results:
2004 Porsche Cayenne Side-by-Side Comparison
Kelley Blue Book Retail: $40,400 – $54,700 Change Vehicle or See Similar Models
Snapshot
EPA Fuel Economy:
City: 13 – 15 Highway: 18 – 19
Available Engines:
247-hp, 3.2-liter V-6
340-hp, 4.5-liter V-8
450-hp, 4.5-liter V-8
Available Transmissions: 6-speed automatic w/OD and auto-manual
Notable Features Pros Cons
• Low-range AWD gearing
• Bi-turbo V-8
• Tiptronic transmission
• Offroad capability
• Seat-mounted and side-curtain airbags
+ Superlative handling
+ Abundant Turbo power
+ Comfortable, supportive seats
+ Porsche reputation for sport
+ Premium luxury fittings of Turbo
- Price, especially the Turbo
- Automatic-transmission hesitation
- Fuel economy
- Occasional rattles and squeaks
- Some wind noise
My Solara is 1 month old and I'm trying to "learn and adjust" to it without using the optional manual shifting.
It's not bad enough to warrant anything drastic on my part, but it's very disappointing for a "luxury" Toyota vehicle.
if i could replicate it, perhaps there is still something wrong with the car i drove in (and yes, the other car i replicated the issue on). i'd have the dealership document the fact that the behavior is not acceptable on either vehicle.
now i'd have it documented that i experienced it [and so did the tech that rode with me], and i've demonstrated my dissapointment with the "luxurious" vehicle's operation. i'd be keeping my options open, and if there is any fix comming, i'd be on a short list to get it first (hopefully).
throughout, i'd be very polite because i'm taking the time of others, and because that's my nature
personally, i would hope i would have detected it on a test drive... presumably there are others accepting it, others that don't notice it, and other's that don't experience it.
If they eliminate the hesitation then we'll be back to burning up transmission clutches and/or transmission fluid like the pre-04 RX vehicles without e-throttle, DBW.
Think about this, in all of the situations involving engine hesitation wouldn't you have just completed a downshift, be releasing the clutch pedal, engaging the driveline, just before, or just as, you're getting on the gas?
Has anyone encountering the hesitation symptom on a regular, predictable, basis yet tried manually downshifting just before applying the gas to see if that alleviates the symptom?
Other than a manual downshift, I can't think of any other way to "tell" the transmission ECU that now we've changed our mind about coastdown, or coming to a complete stop, and now wish to accelerate (quickly?).
For good reason, I've adopted an observer "wait and see" attitude. Probably a good thing.
Rather than cause controversy about whether or not this hesitation is a tempest in a teapot, I prefer to watch it evolve.
As an observer,I have learned through research that it's not exclusive nor unique to Toyota.
There are many other makes and models getting similar publicity about similar hesitation situations.
As an observer, I am only concerned that this issue not become a case of 'Myopic Zeal' and that it not become exclusively focussed on one automaker.
As an Arbitrator of sorts, I have an interest in observing factual evidence and tend to focus on proof of the elements of any contentions made about any issue. I have obviously irritated a few folks in the past by pressing for factual info and validated data in open ended discussions like this, hence the decision to observe rather than actively participate.
I will however, jump in if, as, and when appropriate.
These are clearly not vehicles to which the "boy-racers" are attracted.
In reading the complaints there seems to be a thread, a bare one granted, that the throttle application must be somewhat of an aggressive nature for the symptom to be obvious.
So even if the problem does eventually prove to be systemic, widespread, I'm not surprised at all at the relatively small number of complaints.
What is puzzling to me is that not everyone has the problem. As others have pointed out, it cannot be inherent of the design if everyone is not experiencing it. It seems to be a vehicle-specific defect.
Personally, I think everyone is probably experiencing it to some degree, but it is so slight in some vehicles that it is not noticeable. For some vehicles the lag is longer. This needs to be corrected before someone gets seriously injured or worse.
But absent having the experience myself (I haven't) on reading the many complaints I have assumed "aggressive" acceleration was a part of the equation.
<Think about this, in all of the situations involving engine hesitation wouldn't you have just completed a downshift, be releasing the clutch pedal, engaging the driveline, just before, or just as, you're getting on the gas?
<Has anyone encountering the hesitation symptom on a regular, predictable, basis yet tried manually downshifting just before applying the gas to see if that alleviates the symptom?
<Other than a manual downshift, I can't think of any other way to "tell" the transmission ECU that now we've changed our mind about coastdown, or coming to a complete stop, and now wish to accelerate (quickly?). >
This is exactly what occurs for me. I can eliminate my hesitation issue by d/shifting. I do so having come to HL in 2002 from 16 years in a 5-speed manual BMW. I still try to accelerate thru the curve (as I used to) and it's then that the hesitation occurs. D/shifting helps, but I no longer enjoy doing that. I just want acceleration and power when I "ask" for it with my auto-trans. <sigh>
It also indicates it is anywhere from less to not noticeable at all under less aggressive throttle application. Most reports indicate the latter situation is most prevailent.
It follows then, that those who are aware of it and are familiar with its effect under more aggressive throttle application, are the ones who have control over any safety concerns which might arise.
In other words, it's likely that a driver (of any make or model) to whom it has occurred would be aware of and no doubt make a conscious effort to avoid situations where safety might be compromised. (i.,e.,The "ounce of prevention" syndrome)
Anyone else used 590116's technique sucessfully?
I might add that my wife drives a 2004 Lexus ES330 and it drives wonderfully without any hesitation problems. So there you are two out of the three were okay but the one has major hesitation problems
The latter is a more normal complaint.
Are you by any chance trying to "help" the transmission upshift by lifting the throttle ever so slightly at about the time you think it's "ready" to upshift?
I know of people who have gotten into the habit of doing that and with ECU controls it sends the wrong message.
For what it's worth, I avoided an accident on I-85 while running about 65mph (a car spun 360, to avoid it a tractor-trailer locked brakes and slid into center retaining wall--I can still hear the crunch and smell the rubber) by applying WOT which rocketed me (so it seemed) through a gap and into the clear.
NO hesitation, no hiccup, just wonderful acceleration. Thank God.
I would suggest that the indications are more around "some period of closed throttle valve forward motion..."
My opinions follow:
First off, I have been a very satisfied owner of a Toyota vehicle with 185K miles which I sold only because I needed a Mini-Van. I think Toyota builds quality products. Period. I'm not picking on, nor singling out Toyota.
I am giving the Toyota designers the benefit of the doubt and trust that people reporting hesitation probably represent the vast minority of vehicle owners with DBW systems. I would find it, as an engineer myself, very hard to believe that the designers would design-in nor allow this behavior released into their products.
If they are working on a "fix", I come to the conclusion they are acknowleging a real issue, not merely adding functionality or value.
Further, I consider the reports from drivers with years of driving experience real (I would have no basis for doubting their observations).
So that's my framework.
Is it a safety concern? From my perspective, and in my opinion, yes. Others will disagree. I'm fine with people having different opinions.
Pilot130 provides some good advice on how to avoid or mitigate the issue to a more or lesser extent.
The problem with this, in my opinion - and I'm allowed to have an opinion (BTW I'm not egotistical enough to presume it will be impressed on others), is that fundamentally, the behavior of the system doesn't support the user's mental model which has been acquired from years of driving experience: you call for more gas, and the car responds by reving higher and speeding up.
The same would be true of any ECM/TCM automation (say for example Traction Control) which might de-rate the engine output when vehicle spin is sensed. If and when it occurs, it will be surprising as it isn't something which is anticipated, and the vehicle doesn't respond as one would have been trained up to expect. When that happens, a certain amount of mental effort will be expended trying to reconcile the observation.
Again, Pilot130 asserts that a driver recognize the behavior and anticipate it and use that knowlege of the system response to mitigate... which seems just fine under most circumstances.
But - what happens when you get into trouble with time-pressure? Do humans rely on a high-level cognitive understanding (and prescriptive set of actions to mitigate), or do they resort to something which is more low-level and reflexive?
I don't know the proper terminology, but that is at the essence of my argument. The system should support a natural user-model and operation.
Pilot130 suggests to avoid these situations...recognize they are potentially troublesome...avoid them.
One problem is, we can't anticipate all the scenarios where we may get into trouble.
An analogy (maybe not a great one): lets say you drive a car where the vehicle is showing evidence of problems with the master brake cylinder or perhaps air in the lines, such that when you apply the brakes, a consequence is that *sometimes* the pedal goes to the floor without typical forces applied via the calipers and pads to the rotors.
In other words, it requires you to pump once or twice to get the expected response and bring the vehicle to a stop.
Let's say you know, acknowlege, and anticipate the behavior. Let's say when you drive with the vehicle in this condition, you avoid situations that can get you into trouble. Fine: you're probably OK keeping your distance and periodically testing the brakes to prepare yourself, doubly applying the brake when you sense your not getting proper system response.
But lets say someone one day comes into your lane cutting you off, or someone locks up their brakes in front of you...
Surprised, do you resort to your high-level understanding of the response of the vehicle given it's current condition, or do you stomp on the brakes?
Most drivers would consider engine hesitation, regardless of root cause, to be an issue affecting product acceptance and satisfaction. For many this is also a safety concern, even if others suggest to them otherwise.
Let's just hope that Toyota really is working on a fix (ie, has truly acknowledged that it is a problem, whether it be for safety's sake or for general customer satisfaction), as stated in the Philadelphia Post Gazette article.
My point is that it is really hard to adapt one's thinking and/or actions for situations that occur so rarely that the average pilot (driver!) may never encounter them in a lifetime of flying.
And that may be a reasonably close parallel to what we have here.
(1)Frequency. Regarding this hesitation thing, we already have agreement that it's occurrence is quite low--almost negligible in terms of total units in service.
In terms of any accidents resulting from such a rare occurrence rate--none at all that we know of.
Low score for frequency, at least so far.
(2)Severity. When it occurs, reports range from "momentary" (where most reports are) to "up to two seconds". Majority of reports confirm it occurs at low speeds. Not much "severity", apparently.
(3)Odds of an accident as a result. Its characteristically low speed occurrence aside, the excellent analysis by User777 rules out all but the totally unexpected scenario where a driver has no time to react intellectually.
That puts risk of an accident happening as about the same odds as winning the state lottery.
My opinion? It may be seen as a safety hazard by some, but in the litmus test of objectivity, I don't agree.
I could agree there's an element of risk though.
But so is playing golf.
PS. Has anyone noticed how many posts have actually reported an occurrence, as opposed the number of posts by the same 4 individuals simply discussing its pros and cons?
Wwest--Flight simulators have their place in the scheme of things. Yes, they challenge you with situations that are rarely if ever going to occur.
Their real value is in focussing the user on safety aspects of flying, and keeping the awareness sharp and focussed on prevention/avoidance.
In my opinion, the right to have a driver's licence should include that same type of training, complete with recurrence qualification at intervals.
with full flaps and maybe a bit of slip in, ie in a crosswind situation.
But the 210 is placarded to avoid slips with full flaps! It's a no-no. So I avoid it and use flaps 20 instead of 30 most times anyway, then go to full flaps on roll out to save brakes. The Robertson STOL kit helps a lot in short fields.
I take it you don't agree with my analogy assessing the hesitation as a "risk" rather than a full fledged "safety hazard" (all our collective rhetoric aside, that's what it really is).
That's OK. I can handle your disagreement!
You're a pilot--ever do a Flight Safety Check Ride? If not, you should.
After much research here is my overall opinion on the issue.
Some of us have the hesitation and some do not. This can only mean that not all cars are the same. I think that someone who does not have the problem in their car can drive my car and would definitely notice the hesitation. In addition I think that driving habits of individuals play a part in the frequency and intensity of hesitations in a given day.
Most importantly I think that when cars with more of a problem than others are driven by drivers with perhaps a bit more aggressive driving style you have the worst case scenario (I’m not talking speed racer here just a bit more of a heavy foot). The hesitation can allow any driver to be put into potentially dangerous positions when they need fast acceleration in tight traffic only to have the car hesitate. It really does not matter if the hesitation is .01 seconds or 5 full seconds the result is the same. The driver does not feel confident that the car will perform as required from one acceleration to the next. I think this happens less with conservative drivers. This theory is supported by former posts who have said they felt no hesitation until they where in certain situations such as hard acceleration onto the freeway then felt it big-time. I can count 3 instances personally in 13000 miles where the hesitation in my car contributed to a somewhat close call (most of the time it’s just annoying). All 3 where in heavy slow moving highway traffic while attempting to change to a faster moving lane. The Camry has plenty of power to easily and safely make it in front of on coming traffic but now I’m really never sure when I’m going to get it. At least in my 99 blazer with 95,000 miles I have no doubt when I will get power. In fact now that I think about it I probably would not have tried it in the Blazer. But the Camry has the power to do it and that’s the reason a bought a V6 over a 4.
Some question why the problem is not detected on the test drive. My opinion is that everything is new. It takes time to get used to how everything feels on the road. In my Camry most things that initially felt odd or different went away quickly as I became comfortable with how the car operated leaving only this single problem. It took me about 200 miles to realize that this was something that was not going to go away. I let someone else drive and they noticed it immediately. Some days on my 30+ mile commute one way I will be cruzing along at 70 and start thinking I’m nuts because the car is such a dream at highway speeds. Then I slow down and take the left turn without quite stopping and it happens every time, absolutely ruining an otherwise enjoyable drive.
One of the things that have changed in resent months is that Toyota now admits "they have a problem and are working on a fix". These are Toyotas words not mine. I have heard this statement from the national headquarters and the regional Toyota rep. Both actually used the word “problem”.
The Future,
Toyota will fix the problem in future models. They cannot continue to sell a product with so many complaints about a single issue so they will figure out how to improve new models (possibly a new throttle system), however, I don’t think they will successfully retro fit the existing cars and eliminate the hesitation. Again I can’t live with my Toyota with this condition, dangerous or not.
i disagree with your points (2) and (3).
the previous post by dla2 supports my position.
I disagree that we have agreement on this. Such a statement cannot be made based on what is on this site or even the entire internet. For the sake of example, the sample of FWD 2004 Highlander owners who post on the internet is too small to draw any broad based conclusions. The only conclusions that can be safely drawn is that some experience a hesitation problem and some don't. If you are one of the people experiencing this problem, then you want it fixed whether there are 1,000 or 100,000 people experiencing it.
Based on the Philadephia Post Gazette report, it is certain that it is significant enough in the Lexus and Highlander alone that Toyota is looking into this, but how significant, none of us have enough information in hand. dia2 confirms this in his post.
Another FWD vehicle that has eliminated engine compression braking on the front, driven, wheels.
Obviously the FreeStyle CVT is otherwise being "upshifted" during closed throttle valve coastdown.
i did write that when the event happens (and i wasn't specific as to what the scenario was several posts back), it takes some additional mental effort to reconcile the observation - even if you were sort of prepared for it...
our brains are wired to take note the discrepant.
as a result, one may become distracted momentarily: comparing the event that just occured up to what they've experienced in the past, classifying it, rating severity, recording it...
this is our nature isn't it?
perhaps you assess causality incorrectly ("it might have happened because i did this, or because i didn't do that") and you form a poor or erroneous mental model. it might frighten you even when you were waiting for it. you might blame yourself for driving the car poorly ("surely i must be doing something wrong...it can't be the car or how it was designed"). it might anger you because it continues to occur and your sense is it that it shouldn't. perhaps your flat out dismissed when you report it.
any of these potentially have an impact on your confidence, satisfaction, and your subsequent performance.
posters have indicated there's probably different levels of severity to the event depending on the car and scenario.
we know there's different levels of capability with regard to the driving skills, reaction times, or other ability (visual for example) for the pool of drivers that will potentially have to deal with the issue.
and, we shouldn't forget, it's not just the person who drives the car and the people along for the ride that are potentially at risk by the hesitation. that vehicle is not the only vehicle on the road!
throughout this post, i didn't mention any specific manufacturer, nor did i mention any specific root cause of the hesitation (even though i might personally be more interested in hesitation connected to advanced control system design).
hesitation is bad, no matter who made the car or the root cause.
hesitation is a safety issue for drivers like me.
That was my experience and now for my question about the extent of this problem. Are there completed customer surveys that are available that clearly show the extent of this problem? It seems to me that what we might be seeing an inaccurate sampling of the Highlander owner population as a whole. Of the number of owners who have experienced this problem, what percent have access to computers and have reported their experiences to this or to similar Forums? Any idea of how we might get an accurate idea? My feeling is that this is probably under-reported in the public forums and that the only real sampling could be done via Toyota's collective service centers. Does anyone think that data is available?
For myself, I will consider this a learning experience and try not to place myself in the same situation again. I consider myself a safe and cautious driver (no lead foot) with 30+ years experience, but did not anticipate that the way with which I tried to navigate that turn would be problematic.
Waited to weigh in when I had 1,000 miles on my 2005 ES 330. Here are my impressions on the hesitation issue. I test drove a 2003 and immediately told the saleswoman and my hubby, who were in the car, something doesn't feel right. My Camry, which was totaled, felt smoother with over 125,000 miles.
It was later that I discovered the hesitating transmission problem through internet research.
Then I test drove a 2004 with 3500 miles. A bit better but still not smooth.
Then I test drove a 2005. Ah! Felt right.
My car had 10 miles on it when I test drove it. I didn't take it on the highway during test drives. Initially it felt weird, like mayo in the transmission, when I drove less than 10 mph. That quickly went away and I can honestly say it's getting smoother by the day. For the first 200 miles I didn't do any crazy stops. Essentially babyed it.
Once, while "house shopping" I heard a strange noise. It was my engine groaning as I applied the accelerator ever so slightly. It was almost like it was stalled. I guess the car didn't want to go 1mph. That was disturbing. The car has yet to repeat this, though.
Once in stop and go traffic at the mall the car lurched forward a bit. That was wild. But I am seldom in stop and go traffic. So the other day I deliberately took the long way with plenty of lights. No pausing or lurching, everything was smooth.
I do mostly highway driving. No problem passing or merging so far. The only change I'm making is from the Toyo summer tire to Michelin, cause the toyo is crap/noisy. I have the 17 inch tires.
Do I regret my purchase? Not at the moment. I pray my car doesn't develop the 1-2 second hesitation problem after the 1,000 mile mark.
Hope this helps.
Everything I read here, and in the various Lexus shop manual I have, seems to indicate that Toyota and Lexus are making a serious effort to alleviate the potential for loss of control of FWD vehicles due to engine compression braking on slippery roadbed surfaces.
I suspect, strongly, that during coastdown the transmission is being shifted into the gear range that will result in the least possible engine compression braking.
So, let's say that the transmssion ECU firmware has just entered the procedure, software/firmware "sub-routine", to upshift the transmission as a result of closed throttle valve coastdown.
Even if the programmer foresaw that this sub-routine should be interuptable, the mechanics of the transmission itself may have dictated that the shift sequence must be fully completed before another can begin.
So, you now just happen to apply slight throttle (or more??) at the very instant the upshift software sub-routine is entered. Not only does the transmission now have to fully complete the upshift, as soon as that is done it must now fully complete a downshift in order to be in the proper gear for acceleration.
In my experience it is not at all unusual for the fuel injectors or the ignition to be shut off (ever so briefly, 1/4 turn of the engine) during a transmssion shift, to prevent a shift "lurch". So I can completely understand a decision to delay engine power deverlopemnt with DBW or e-throttle.
Factual references from the 2001 RX300 Lexus shop manual:
The 2001 RX300 takes 1.2 seconds to shift into drive when the shifter is moved from neutral to "D".
Torque converter lock-up is disabled anytime the brake is applied.
When the throttle valve is fully closed and the transmission is in 3rd gear it is automatically shifted into 4th.
The diagnostic procedures direct that a check for the "feel" of engine compression braking be present with closed throttle operation with the shifter in 2nd, or 1st, but not in "D".
I have a 2004 RX 330, purchased in August. It is currently at the dealership for the second time for lagging/hesitation. I am at my wit's end. Now I can go in armed with the Post article at least to back up my case.
The dealer is saying the vehicle operates normally, and each time wants to reset the ECU. Before the RX, I had a Mitsubishi Evolution (bad clutch on every car - even when not dropped), so you can imagine the pain I'm going through with a hesitation/lack of immediate acceleration.
I don't really know what to do if the dealer won't help me. I called Lexus customer service who said my only option is NCDS dispute settlement. I've never been in court before, don't want to start now. Also, I do not like a dealer telling me my car is driving normally when I can prove it's not.
Anyway, keep up the good forum. Let's get our cars fixed. I could go on all day with details about my hesitation, but it seems similar to others' experience. And yes, I pay very close attention to my car, and yes, the hesitation is an extreme distraction.
Also, out of curiosity, does anyone have a film on the inside of their windshield causing them to run the defrost all the time? Cause I do, but the dealer says no, even though it's there and I can show them. Jeez. Running the defrost runs the a/c which further kills acceleration and ruins gas mileage. I'll tell ya, never again a Lexus.
But the most likely problem with your RX is an extremely flawed climate control system design.
I had the dealer set both c-best options such that the A/C doesn't run in either mode automatically, only if I turn it on manually myself.
I never run the A/C unless I need it for cooling.
The biggest problem with the entire Toyota/Lexus product line insofar as the automatic climate control is concerned is lack of enough outflow, fresh air incoming and stale air exhausting.
The simplist way to overcome the problem of the passenger cabin's relative humidity remaining too high is to dramatically increase the blower speed in order to force the humid air quickly out the exhauster port.
If your windshield continues to fog over then it will also help to run the system continuously in the combined footwell/windshield mode.
If the fogging condition should get out of hand the quickest way to clear it is to change the temperature setpoint to max heat (quick clockwise twist), lower a rear window slightly, and then activate defrost/defog/demist mode. If the blower is still in automatic mode it speed will rise with the setpoint.
Use of the A/C to dehumidify the incoming airflow, an unlikely possibility at best, will only result in another windshield fogging incident a few miles down the road.
I will tell the dealer about the c-best options. You are right at the end of your message, "another windshield fogging incident a few miles down the road," ... this is exactly what happens. We'll see what they do when I get the car in 3 days.
At the instant the A/C is turned off there will remain a significant level, thin film of mositure, coating the 10,000 square inches of evaporator cooling vane surface area.
The ONLY place this moisture can go as it now evaporates is into the passenger cabin and then, hopefully, out the exhauster port.
best
Shifty the Host
2001 RX300 Repair Manual, Volume 1, page DI-191, (Input Turbine Speed Sensor):
"CIRCUIT DESCRIPTION
This sensor detects the rotation speed of the input turbine. By comparing the input turbine speed signal NT) and the counter gear speed sensor signal (NC), the ECM detects the shift timing of the gears and appropriately CONTROLS THE ENGINE TORQUE and hydraulic pressure in response to various conditions, thus performing smooth gear shifting."
In other words the RX300 shifting sequence is completely an open loop servo system. Once the transmission ECU energizes the correct electrical solenoids for the new gear position the only feedback to verify new gear engagement completion is via the comparison of the transmission input shaft speed and the output shaft speed.
And I would imagine the engine torque output is controlled via the "throttling" of the fuel injectors since my 01 does not have DBW/e-throttle.
So, let's assume I'm at 21-24(19-23{AWD})MPH and fully close the throttle while waiting for a merge opening on the freeway. The system detects the coastdown circumstance and begins the upshift sequence (page SS-22, same volume) from 3rd to 4th just as I depress the gas pedal to mid-point to accelerate and merge.
Being open loop means that the upshift must complete and the upshift must be "verified" via the correct rotation ratio comparison between transmission input and output. And now once that shift completion is verified a new downshift command will be issued and verified.
In the meantime the engine torque is suppressed via fuel injector "throttling".
And this is for an 01 RX300
So, now the question becomes when did Toyota/Lexus discover that these transmissions were failing prematurely due to the "too quick" reapplication of engine torque. Remember that while the engine is being starved for fuel via closed injectors I may have the throttle control valve wide open resulting in an extremely LEAN mixture. The knock sensors will be complaining mightily!
Could they extend the dethrottling period for the fuel injectors without affecting the emissions requirements?
Could the engine, or engine related components, suffer premature failure due to short periods of extremely lean mixture spread over years of operation?
Certainly not if as of 04 Toyota/Lexus uses DBW/e-throttle and shuts down fuel and air flow during these double shift sequences.
Fuel but no spark would make dieseling, knocking, more pronounced, and if not that then a rich fuel/air mixture reaching the converters would do them serious damage over the log term.
As I stated in post #92, my RX 330 was at the dealership getting checked out. I picked it up today and here is what happened:
First, I want to note that I not only brought it in for the hesitation, but erratic transmission behavior. Even the loaner RX 330 had problems, such as getting hung up at 4k RPMs when accelerating from a cruising speed of 39mph. Additionally, my girlfriend, who's an engineer was with me on the ride.
My service paperwork states: "Customer states when driving at city, when downshifting, vehicle goes to lower gear and does not hold at that gear."
I went in and met with the Master Technician/Shop Foreman (as stated on his card). I first presented him with the Post newspaper article that discusses RX 330/Toyota 5 speed auto tranny hesitation (link available on this thread), and he scrutinized it. He had not seen it before. He then had a service writer photocopy it.
He said that Lexus is aware there's a problem, they've received many complaints, but they don't have a fix for the RX 330 or ES 300.
The foreman then went on a road test with me, where I drove the RX, and where I clearly demonstrated problems with the tranny.
First, while cruising between 20 and 35mph on city streets, I demonstrated how the car downshifted past 2 gears before settling on a gear. Secondly, we went on the freeway. I drove at 50mph, pressed on the gas, and the vehicle took nearly 2 seconds before any acceleration occurred. Lastly, we returned to city streets. There, cruising between 20 and 35mph I demonstrated the erratic transmission, which is part of hesitation. When depressing the gas pedal appx. 1.5 inches, the car would hesitate, then downshift, revving the rpms up to 4k. However, on several unpredictable occasions, it downshifted and hit 5,500 rpms, throwing all of us back in our seats, nearly causing the FWD to lose control until the trans. upshifted.
At the dealership, he acknowledged all of my concerns, and that there were problems with the vehicle. He had this typed on my service paperwork:
"Cust. duplicated condition during road test. No fix for cond."
Having read about unsuccessful attempts to arbitrate the car, I suggested several options. 1) For my dealership to buy the car. Their answer was to give my mid to high 20s, resulting in over 10k in losses for me. I did not do it. 2) That I could open a case with Lexus, go above the dealership, and have someone from corporate (a district manager) road test the car with me. The foreman agreed, said I could use his name when calling Lexus. He then offered to reset my ECU which I refused. They did it the first time I took the car in, and the vehicle was even less responsive than now.
Then my girlfriend and I discussed a serious issue with him. If Lexus is calling the hesitation "normal," they do not understand how distracting and dangerous it is. We reminded him that at one point, car companies had cars exploding, rolling over, and tires peeling off and it was normal. But it sure wasn't safe, and sadly, people died.
So I called Lexus customer service who tried desperately to discourage me from opening a new case, stating that I had already reported the hesitation and Lexus has taken their stance on it. They told me that Toyota was working hard to fix the problem, but there was nothing they could do. I said that I had a new concern, the erratic shifting and wanted a new case. Lexus said they would contact the foreman and get the whole story before opening a new case. But they said when it comes to the hesitation, I'd have to go through NCDS arbitration to get them to buy back the car. And I informed her of the safety issues, and that I don't know of anyone having success with NCDS on this issue.
As of Tuesday night, I have not heard back from Lexus on what they're going to do. But I'll say this... What is unfortunate, is that they're still selling vehicles with 5 speed automatic trans., even though they know there's a problem. It is unethical and sad. Unfortunately, I bought one of those cars.
Thanks for everyone's input.
HOST, sorry if this is off topic, but...
If there's any way to get rid of this car because of the hesitation without losing a bundle of money, I'd imagine lots of people on this thread would want to know. Ideally, I'd like to see Lexus/Toyota take this seriously and take action.
I'll let everyone know what develops.