Last post on Jul 08, 2012 at 5:54 PM
You are in the Toyota Camry
What is this discussion about?
Toyota Camry, Sedan
#971 of 1078 Re: 2009 Camry LE V6 Question/Problem [210delray]
Feb 09, 2010 (12:53 pm)
What is your opinion of this drive by wire system? I have had Toyotas in 1995 and 1998 with no problems regarding computers affecting acceleration or smooth shifting as I guess they had none. Cars worked fine with good gas mileage. Computer stuff came and had to get my 07 re-calibrated. The cars of the 90's worked fine--why does Toyota have to change stuff that does not need changed? I see no better gas mileage or anything else from this drive by wire. Your thoughts?
#972 of 1078 Re: 2009 Camry LE V6 Question/Problem [exler]
Feb 09, 2010 (6:46 pm)
I don't think drive-by-wire is the villain it's made out to be. I have it in both of my Camrys, a 2004 and a 2005. No problems in over 114K miles of combined driving. I don't think there's a car built today that doesn't have drive-by-wire.
Drive-by-wire is a must for precise response of traction and stability control, where power to the engine must be cut very quickly. In theory, it should also permit better fuel economy, but I think for the average driver, the improvement wouldn't be measurable.
#973 of 1078 Leaving car for 45 days...
Feb 10, 2010 (8:13 am)
I have a 2009 Toyota Camry LE. I am going on a long vacation and i would need to leave the car for around 45 days at a airport parking. Is it ok to leave the car for such a long time. Will it have any effects on the tires, batteries, engine etc?
#974 of 1078 Re: Leaving car for 45 days... [santocs]
Feb 10, 2010 (8:18 am)
Should be fine, assuming nobody has taken it.
Given the price of parking at most airports I've been to however, I would think you'd be better off getting a ride/cab/limo to and from the airport.....rather than paying 45 days of parking.
#975 of 1078 Re: Leaving car for 45 days... [santocs]
Feb 10, 2010 (9:04 am)
Hi there, Santocs.
You asked this question last November and got 15 replies (including mine.)
Was there something we neglected to tell you?
How did it work out last time?
#976 of 1078 Re: 2009 Camry LE V6 Question/Problem [exler]
Feb 10, 2010 (10:50 am)
"...why does Toyota(/etc) have to change stuff that does not need change?.."
While there are some very definite advantages to DBW, some HIGHLY advantagous, Toyota/etc's base reason for adopting DBW fleet wide had its origins in a design flaw in the U140E/F ("F" = F/awd) transaxle developed initially for the RX300.
Since Toyota/etc wanted to adopt (~2002) the more fuel efficient U140E across the fleet something had to be done to "cover-up" the design flaw. So DBW was adopted to "protect the drive train", prevent premature failures of the U140E transaxle when a downshift could not be accomplished in the time allotted, driver expectation of downshift "time".
So DBW was used to "hold-off" rising engine torque in response to gas pedal position/depression for 1-2 seconds to allow the extended time needed for the transaxle to accomplish a downshift shortly following an upshift.
Here we are, 2010, and Toyota/etc is still struggling with this same issue. Whereas Ford, with the new Edge, simply adopted a variable displacement ATF oil pump, low volume for HIGH engine revs and incrementally higher, selective volume, for lower engine revs.
#977 of 1078 Re: 2009 Camry LE V6 Question/Problem [wwest]
Feb 10, 2010 (11:20 am)
Interesting theory you have there. (Wondering where it was published initially. Was it by Toyota, or a third party engineering journal?)
I'm sorry, but I don't understand exactly the meaning of your sentence, "prevent premature failures of the U140E transaxle when a downshift could not be accomplished in the time allotted, driver expectation of downshift "time". "
The part that confuses me, I guess, is the reference to the "timing" of a downshift. I wouldn't have thought that most drivers/owners gave a rat's butt about the timing of a downshift in their automatic tranny. If you could use a "real driving scenario" to explain what this means, I'd appreciate it.
Also, my question is (I'm an unlucky buyer of an 07 Camry, which I believe was its first year of application in that model).....what was wrong with the good old "planetary gear system" (or whatever the heck it was) OLD style Camry transmission? I never heard any horror stories about it. Were there lots that I missed? (since I was busy driving my 1997 manual transmission model?)
Thanks for additional insight, Willard.
#978 of 1078 Re: 2009 Camry LE V6 Question/Problem [wwest]
Feb 10, 2010 (11:23 am)
>Whereas Ford, with the new Edge, simply adopted a variable displacement ATF oil pump, low volume for HIGH engine revs and incrementally higher, selective volume, for lower engine revs.
That's much more effective from an engineering standpoint, but it probably costs more than covering up a shift lag by changing the engine control in the software. What I think you're saying is the complaints about a long shift lag when someone was slowing down on a ramp and floored the accelerator to merge into a coming available slot caused toyota to change their software. Now the engine doesn't produce much power for a period of time until the transmission has had time to effect the long downshift time and is ready for more engine torque. So the car just doesn't go anywhere but feels like the motor is accelerating but it's only at low power.
Is that it?
#979 of 1078 Re: 2009 Camry LE V6 Question/Problem [notmybmw]
Feb 10, 2010 (11:24 am)
I don't think planetary gear system automatics have been used since the demise of the GM 4-speed Hydramatic back around 1964, with the notable exception of hybrid-electric cars like the Toyota Prius.
Just a suggestion for Mr. West: Please avoid obscure abbreviations and all caps, and try to explain things in a way a non-engineer can understand.
#980 of 1078 Re: 2009 Camry LE V6 Question/Problem [notmybmw]
Feb 10, 2010 (12:24 pm)
Prior to developement of the U140E/F transaxle the ATF gear type oil pump was always pumping at full volume, the volume that was dictated by the engine RPM. Just downstream was a pressure holding accumulator and beyond that a pressure relief value so line ATF pressure never exceeded a specified level.
Much the same as the power stearing punp, HUGE energy loss due to pumping so much fluid up to pressure and then simply dumping it back into the sump if it was not needed.
With the U140E/F the spring loaded pressure relief valve was eliminated in favor of an ECU controlled solenoid that determined the ATF line pressure in "real-time". So while the ATF pump was still pumping VOLUMES of fluid most of the time it was no longer doing so under a HUGE back pressure.
So if ATF line pressure was to be controlled, varied, under real-time requirements, there was no reason to keep the pressure holding accumulator. So it too, was abolished.
Now, with the engine at idle, the condition it is likely to be in when you release the gas pedal for a short/brief coasting period, and with the upshift resulting from that same gas pedal release, there is, will be, NO reserve ATF pressure in preparation for that upcoming(??) downshift.