Last post on Sep 30, 2010 at 1:44 PM
You are in the Toyota Camry
What is this discussion about?
Toyota Camry, Sedan
#19 of 48 Re: 2005 Toyota Camry jerkiness. [bpsmicro]
Jan 23, 2006 (4:58 pm)
I have a friend that works at the dealer who looked it up for me and actually printed it out for me to give the service writer.Look,a TSB is a TSB and any dealer should have no problem with taking care of it for you no matter what!...plus they get paid to do it.
#20 of 48 Re: 2005 Toyota Camry jerkiness. [2k1trd]
Jan 24, 2006 (7:10 am)
Yeah, you're right. I'm probably just paranoid.
But here's another question: up here in Canada I'd expect them to refer to the same TSBs. Anyone know if they'd look up the Canadian version (refers to kph instead of mph presumably) via the same number? I'd also be curious as to whether the Canadian equivalent of the "Federal Emissions Warranty" applies in this case.
Mind you, if they tried to screw me on the warranty coverage, it sounds like it'd be worth paying for anyway.
#21 of 48 Hesitation is Back
Feb 26, 2006 (3:14 pm)
I guess the TSB didn't 'take'. Hesitation is back and just as bad as ever. Wife says get rid of it. I'll start looking at subarus as soon as we send in our last house payment.
#22 of 48 Re: Hesitation is Back [mert2]
Feb 26, 2006 (10:38 pm)
Have your service manager replace the accelerator pedal assembly with one that has an VPA output voltage of less than 0.8 volts when at rest, fully released. Less than 0.6 volts would be even better.
The engine/transaxle ECU firmware is looking for a voltage of less than 0.8 volts as an indication of the accelerator pedal being fully released, at the idle position. The factory tolerance for an acceptable output at rest is 0.5 volts to 1.1 volts.
Looks like a design flaw.
Methinks there is a very BASIC misunderstanding going on about the engine/transaxle delay hesitation.
There is the STANDARD delay EVERYONE experiences at one time or another.
Toyota is very definitely, by their own admission, using the DBW, E-throttle system, to delay the onset of engine torque developement to "protect the drive train", give the transaxle downshift clutches time to fully and firmly seat. Not any different than any of us would do when downshifting a manual transmission, at least most of the time.
This "standard", normal delay, hesitation, is being noticed, noticeable, because prior to DBW our engines's torque began to rise the instant we depressed the accelerator. That's very likely also why the pre-04 RX series is enduring a serious number of premature transaxle failures. ASL= more frequent upshifts and downshifts, no DBW, NO delay = an inordinate level of clutch frictional surface wear.
Insofar as I can tell the new automatic transaxle shift logic recommended by Sierra Research in April of 1999 was adopted for the RX before my 2001 RX300 was built.
So, let's say that the "standard" delay is on the order of 200 to 500 milliseconds (2/10's to 1/2 a second). That's enough for everyone to take notice, especially those having previously, or still, driving older versions.
Now, lets assume that a very small number of accelerator pedal assemblies leave the factory with the "at rest", fully released, sensor output voltage on the high side of the acceptable tolerance, above 0.8 volts, as high as 1.1 volts.
First there is the fact that the factory manuals indicate that the low end of the accelerator pedal's "usable" range is with the sensor's output explicitly at 0.8 volts. It makes perfect sense that the designers would want some slack, tolerance, a "widow" (0.0xx to 0.8 volts) of voltage ranges that represent the idle, fully released, position.
But now we have some pedals in use by customers wherein the sensor never falls below 0.8005 volts.
Why would that matter?
Because the transaxle shift control design would not likely upshift if the pedal were fully released. Fully released would be assumed to mean "I wish to coastdown to a lower speed" and upshifting would not be conducsive to that.
On the other hand what if you just ease off the accelerator pedal slightly? The logic would be such that the system would assume "I want to just begin cruising along at about this speed", and an upshift would then be very appropriate.
What if a part of the engine/transaxle ECU firmware, due to those flawed tolerances, just simply couldn't detect the difference between a partial accelerator pedal release and a full release.
Definitely would have a much greater propensity for upshifting, right?
And what other aspects might result from the firmware being "confused" (why is the driver on the gas and brakes at the same time?) in this manner?
Maybe a "watch-dog" timer master firmware reset?
In effect a engine/transaxle ECU firmware "reboot".
How many seconds might that take?
#23 of 48 Re: Hesitation is Back [mert2]
Feb 27, 2006 (6:13 am)
mert2, Sorry to hear that the TSB fix did not last for you. I have forgotten the details of your problem -- can you describe your hesitation again? How long/how many miles did the TSB "correct" the problem? Was it a gradual return of the hesitation symptoms or did it happend suddenly?
Thanks for the update.
#24 of 48 Re: Hesitation is Back [wwest]
Feb 27, 2006 (7:52 am)
wwest -- I'm highly suspicious that the service dept. will have any idea what you're talking about.
these are the same guys that didn't know there was a tsb out, and when I got them to look it up they tried to charge me for it because they thought it was an enhancement, not a fix.
the other shop in town has played parts roulette with me (replace this part, see if that gets the light to go off).
do you have something from toyota that I can take to them?
#25 of 48 Re: Hesitation is Back [mert2]
Feb 27, 2006 (9:25 am)
There is a very well defined diagnostic procedure for in car reading/checking the accelerator pedal VPA sensor output voltage at WOT and at rest, fully released positions in the factory repair/shop manuals.
The manual indicates that the acceptable VPA output voltage range at rest must be between 0.5 volts and 1.1 volts. IMMHO the problem is that if it happens to be above the 0.8 volt level the engine/transaxle ECU will not be able to easily discern the difference between fully released and partial but just slight application.
#26 of 48 Re: Hesitation is Back [mert2]
Feb 27, 2006 (11:04 am)
Can you do me a favor..??
I have little doubt that Toyota gets it right.
By that I mean if you disconnect the battery and then reconnect it after being certain the accelerator pedal is FULLY released the engine/transaxle ECU will at that time RECORD the VPA (accelerator position sensor) voltage that indicates a fully released accelerator pedal.
That stored voltage parameter should not change over time and multiple drive cycles unless the ECU has "reason" to suspect the sensor voltages have drifted from the original ones recorded.
That might happen, for instance, if you often brake with your left foot, even ever so slightly, while also have a very light touch on the accelerator pedal. That might result in the ECU "thinking" that the accelerator pedal sensor outout voltages have drifted over time and the initially recorded IDLE voltage needs to be adjusted to fit the new accelerator "idle" position.
Or suppose you often get into the car and unconsciously apply a light pressure to the gas pedal just as you switch on the ignition?
So, here is my suggestion.
Disconnect and reconnect the battery being sure the accelerator pedal is fully released.
Now, each and every time you get into the driver's seat be sure the very first thing you do, consistently, is put your right foot flat onto the carpet. Now put the key in the ignition and start the car with your foot still flat on the carpet.
Before shifting into any gear use your right foot to apply the brake. Do not move your foot to the accelerator pedal until the transaxle is "settled" into the selected gear.
Try that procedure, consistently, for a week or more of drive cycles and see if the hesitations returns.
#27 of 48 Re: Hesitation is Back [wwest]
Feb 28, 2006 (11:10 am)
Already do that.
Years of driving a standard has me in the habit of stepping on the brake (right foot) when I start the car. No foot on the gas.
#28 of 48 Re: Starting your car, no foot on the gas.
Feb 28, 2006 (2:11 pm)
OK. I've driven mostly manuals since getting my license decades ago. Now I drive automatics (i cry). Anyway, aren't you supposed to put your left foot on the rest pad (if you have one) and never use it? I certainly don't.
Unless I'm in a panic stop. There have been a few times where I've gone for the phantom clutch and brake at the same time.
But seriously, does anyone use their brake and gas in their automatics at the same time? If so, they must have idling issues right? And, are many applying gas when starting? You're not supposed to...