Last post on Jul 31, 2013 at 8:42 PM
You are in the Toyota Avalon
What is this discussion about?
Toyota Avalon, Transmission, Sedan
#117 of 379 Re: Avalon Owners [captain2]
Jun 05, 2006 (6:52 pm)
The problem is NOT due to the use of DBW.
I can assure you that the DBW system in my 2001 Porsche C4 works perfectly well, as I suspect all DBW systems coupled with manual transmissions wherein the driver is reponsible for current, or next gear slection, and appropreate application, use of, the clutch pedal.
The problem arises when the engine/transaxle firmware must take on the responsibility of "guessing" what you, as the driver, will next do.
Do you intend, will you, come to a full stop, or will you begin to accelerate before coming to a full stop. Regretably Toyota?lexus' firmware assumes you will come to a full stop.
Put the clutch pedal back in, non-operative, and the firmware will get it right every time.
Think about it, with the clutch pedal in you can be in any gear you wish in preparation....
#118 of 379 Re: Avalon Owners [wwest]
Jun 05, 2006 (8:56 pm)
This of course, is now of only forensic interest to me, but I think the transmission is only partly the issue. In my ex-Avalon, when the accelerator was depressed even with the transmission in Park or Neutral, there was a delay in engine response. In some circumstances. this combined with the transmission hesitation could cause close to a 2 second delay between throttle input and vehicle response. I experimented with the throttle position, but the DBW system seemed to "relearn" the gas pedal "home" position, compensate and reintroduce the lag. I had attributed this to the DBW system.
I have found the Honda and Nissan systems to be much "tighter" in their responses and they don't feel any different than a conventional system. I am extremely curious as to why Toyota would continue to propagate this, even if it affects, as they claim, only a small percentage of vehicles.
Perhaps the complex "adaptive" and anticipatory multi-map logic employed by Toyota is just not the right solution. It seems that a fast-responding reactive system is better in real life situations, and this is easily achievable with the speed of modern processes.
One more thing, did a NOVA really get Apollo 11 to the moon?
#119 of 379 Re: Avalon Owners [captain2]
Jun 06, 2006 (4:15 am)
I think we have found through pretty exhaustive discussion on this topic that the problem can range from a minor nuisance (what you are describing) to a downright safety issue (chodie's description). Not every vehicle seems to have the hesitation to the same degree.
#120 of 379 Re: Avalon Owners [scoti1]
Jun 06, 2006 (5:07 am)
scoti1 - would suggest to you, as I posted earlier, that 90% of us Av owners out there do not find it terribly bothersome and that, of those that do, the inability of the system to adapt to an all-on/all-off driving style is likely the culprit. The Avalon simply does not respond correctly to sudden throttle changes from lower speeds, make it a firm (but gradual) application of throttle and the problem 'disappears'. Wwest is correct, there are certainly livable DBW systems out there and there are also many that, in one form or another, are even worse. But, either way, it would make no sense that one Avalon would be different from another - until it has had a chance to 'learn' something that it can't cope with.
From my point of view, the jury is certainly still out on all this electronic control crappola being put into all cars these days. It will get worse before it gets better and is certainly something we all will have to live with.
#121 of 379 Re: Avalon Owners [alan_s]
Jun 06, 2006 (9:13 am)
There could, of course, be a quite reasonable explanation for engine response to the accelerator pedal while in park or neutral. Were I writing the control firmware in this case I might delay the onset so as to be sure of the driver's intent.
Application of pressure to the acceleration pedal while in park or neutral would in most cases be an anomaly, Ooops, bumped the pedal and only sustained application "should" be responded too.
And no, I never heard that Nova story/rumor but there is the one about a clone of Ken Olsen's 16-bit off-spring rescuing the pioneer 10 program as the probe exited the solar system.
#122 of 379 Re: Percentage of Avalons with hesitation, bad engine [lzc]
Jun 05, 2006 (5:28 am)
IMO, of course, but wouldn't worry too much about tranny issues - it has nothing to do with the trans itself but rather the way it is programmed to select gears - an FE thing that seems to put the trans in the highest gear possible. This creates a 'hesitation' on heavy reapplication of throttle from lower speeds. Since the software that does this must be shared with all Toyotas so equipped, the DBW hesitation should exist with not only Avs. but also Siennas, RAVs etc. and possibly even the 6 speed Camry and the 07 Av. From personal experience, do not find it objectionable, have 'adjusted' my driving style to compensate for the transmission behavior so it very rarely happens - and I would rather 'put up' with this condition than give a few mpgs back.
The 3.5 2GR engine has not had any documented issues from a reliability standpoint and is actually the best part of the whole car. It is, by nature, slightly noisier than the old belt driven OHC 3.0 and 3.3 engines it replaced. The clicking noise you hear at idle is actually the direct feul injection. In slightly modified forms this engine is now in not only Avs, Camrys and RAVs but now about every Lexus model.
The Camry transmission problems are in fact a manufacturing defect (snap ring) and apparently effected just a few hundred that had Japan assembled trannies. Haven't heard anything about any transmission programming issues though, so the behavior may be better in the 07 Av.
Whether these 'problems' effect sales remains to be seen -things like this sure didn't hurt Honda very much a couple of years ago after a bout of tranny failures (overheating) in Accord V6s and TLs.
Have had my Av for well over a year now (28k) and think it is the best car I've ever owned - but maybe that's just me?
Jun 06, 2006 (5:51 am)
Don't want to sound silly but if there is some time/mileage
point where the trans stops learning and doesn't learn any
more,than maybe we need to get trainers for these transmissions,have someone whose trans is perfect train
your car for you.I wonder if we had all the posters with
problem transmissions switch there cars with the non-problem ones and let those drivers train their cars what
would actually occur.
#124 of 379 Re: DBW [oilcan2]
Jun 07, 2006 (5:02 am)
If you follow wwest's posts on this and other boards, you will see that the hesitation does not appear to be a transmission learning issue. Wwest has looked into this and found that the learning resets itself everytime you start the car and makes judgements on your driving style within the first few minutes of driving. I am completely non-technically trained so I am sure wwest can explain this better. but if this weren't the case, how could you ever have multiple drivers on one car, especially rental cars?
Jun 07, 2006 (6:22 am)
Guess I'm trying to establish what the difference is from
one avalon fron another,assuming no mechanical problem,it
would be interesting to get a driver who has a so called
perfect av trans(even if it's in his mind)to drive a problem one and see if he has any luck with the trans.
Jun 07, 2006 (6:57 am)
This difference may be among drivers; not cars. Numerous Avalon drivers who had "hesitation" problems were able to improve their car's response by changing the position of the foot on the gas pedal.
Changing their foot position seems to have worked also for readers who drive other car brand with similar problems. See
#11794 How do YOU step on the gas pedal? Initial Poll Results
and many following posts.