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Coasting Or Decelerating


jig50
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I have notice this weird sensation when taking my foot of the gas pedal when coasting to a red light. Initially everything seems fine, then I feel a slight disconnect with tranny then it connects again then disconnects again and so forth until I come to a stop. In other words, coming to a stop is not one fluid, linear operation. It appears to be the tranny is downshifting thru the gears as the car is decelerating. I have never been aware of this with any other car I have owned and find the characteristic a little strange. Has anyone else noticed this? It is not a flare related issue. Yes the rpm's vary a little throughout the gear changes, but nothing drastic.

On another note, the occasional flare I experienced seems to be much less. I don't know if the tranny has "learned" my driving style or whether I have altered my driving style to accomodate the tranny. I am going with option 2.

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That's the way the ES350 and other recent Lexus models were designed. In fact this feature was patented.

Read this> http://www.freepatentsonline.com/5115896.html

Wierd that you know this. I noticed this myself and told the dealership. I thought it was the flare. The dealership told me the same thing. The foreman states that it's Lexus' way of keeping it in the same gear as long as possible so if a sudden acceleration is needed it would contain the most power by staying in the most proper gear. What I've noticed though is that there is actually a delay when you suddenly accelerate. So how can this be good? They convinced me it was better than anything out there so... Anyways, I'm glad I'm not the only one to notice it. It gives is kind of a sporty feel i guess.

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That behavior is one of the first things I noticed about the IS250. It's also the first 6-speed auto I've owned. The downshifting as you come to a stop is somewhat annoying to me because it makes a very "un-smooth" ride to a stop. The brakes feel like they clamp hard then let go, then clamp hard, then let go.

With the ECT switched OFF, this effect is reduced in our 2006 IS250. With the ECT switch off, it also feels like the compression is reduced and you coast more easily when decelerating. I don't know what effect it will have on the other models. I have the ECT swithed ON because I like the higher RPMs between shifts, and the feel of compression when off the throttle. Also, in my other cars and trucks with an PWR and NORMAL button, with the PWR on the gas mileage was better. That's just my worthless opinion.

Google for:

wwest DBW hesitation coastdown

or:

wwest NCF "gas pedal"

Latest Toyota/Lexus models have new, additional. "learning" firmware within the engine/transmission controlling ECU that tries to judge/determine your near- future intentions when you let up on the gas pedal.

QUICK/FULL "letup" = presumption of driver intention to coastdown to a lower speed, remain in current (low, lower..??) gear ratio.

S.L..O...W..../partial "letup" = presumption that driver wishes to enter cruise mode, upshift the transmission if appropreate.

This is, seemingly, Toyota/Lexus latest "FIX" for the design flaw incorporated back late in the last century via "abolition" of the ATF pressure accumulator to sustain fluid pressure during periods when the engine is, might be, at idle and a gear shift is required immediately following a previous gear change.

That's why DBW was adopted as an earlier fix. DBW could be, was used, is STILL used, to delay the onset of engine rising torque when you depress the gas pedal and there is no fluid pressure reserve to provide the required downshift since the transmission has just completed, or is in the process of completing an upshift due to your "just" previous gas pedal "lift".

I guess now with this NCF, New Car Feature, we need to "teach" our right foot how to best manage the gas pedal so as to not encounter a "double shift" instance and therefore a 1-2 second engine/transaxle-transmission downshift delay/hesitation.

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I guess now with this NCF, New Car Feature, we need to "teach" our right foot how to best manage the gas pedal so as to not encounter a "double shift" instance and therefore a 1-2 second engine/transaxle-transmission downshift delay/hesitation.

[/quot

This is the 2nd automatic trans. where I have had to "learn" to work around the quirks of the trans. The first vehicle was a 2005 Solara v-6. The 2008 ES-350 tranny seems improved over the Solara. I feel confident that by 2015, Toyota will have worked out the "kinks" in the drive-by-wire tranny and owners can settle back in to having a passive relationship with their automatic transmissions. Until then, consider yourselves back in school. Now get back in there and "learn" some new throttle management strategies. I love technospeak in new product brochures--gets me every time <_<

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I guess now with this NCF, New Car Feature, we need to "teach" our right foot how to best manage the gas pedal so as to not encounter a "double shift" instance and therefore a 1-2 second engine/transaxle-transmission downshift delay/hesitation.

[/quot

This is the 2nd automatic trans. where I have had to "learn" to work around the quirks of the trans. The first vehicle was a 2005 Solara v-6. The 2008 ES-350 tranny seems improved over the Solara. I feel confident that by 2015, Toyota will have worked out the "kinks" in the drive-by-wire tranny and owners can settle back in to having a passive relationship with their automatic transmissions. Until then, consider yourselves back in school. Now get back in there and "learn" some new throttle management strategies. I love technospeak in new product brochures--gets me every time <_<

Back in the 1950's when automatics were just beginning to be more common many them tended to hold the lower gear(s) a bit too long. Of course for many of those that arose out of the fact that only two gear ratios existed. So many of us learned that the transmission could be caused to upshift a bit sooner, softer and smoother shifting, than normal via a momentary "lift" of the gas pedal.

"Back" to the future...??

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Randy,

I'm afraid then that in the future you will be restricted to stick shift transmissions.

With a stick shift you can push in the clutch pedal, downshift, release the clutch pedal, and then apply pressure to the gas pedal for GO..!!

With an automatic the you only need to "learn" to apply pressure to the gas pedal.

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