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Sedans Toyota Camry Toyota Camry TSBs and Trouble Codes
47 messages, Last post on Oct 16, 2008 at 7:03 PM
You are in the Toyota Camry Forum. Your Hosts are pat & karens
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Replying to: bpsmicro (Jan 23, 2006 2:51 pm) Then find a new dealer, quickly. |
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Replying to: bpsmicro (Jan 23, 2006 2:51 pm)
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Replying to: 2k1trd (Jan 23, 2006 4:58 pm) 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. |
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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.
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Replying to: mert2 (Feb 26, 2006 3:14 pm) 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. And now..... 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?
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Replying to: mert2 (Feb 26, 2006 3:14 pm) Thanks for the update. |
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Replying to: wwest (Feb 26, 2006 10:38 pm) 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?
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Replying to: mert2 (Feb 27, 2006 7:52 am) 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. |
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Replying to: mert2 (Feb 27, 2006 7:52 am) 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.
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Replying to: wwest (Feb 27, 2006 11:04 am) 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.
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