Transmission "jerky"? - Toyota Nation Forum : Toyota Car and Truck Forums

lets456 · 06-24-2010, 08:39 AM

Ok... I have a 2008 Highlander base that I bought used. I am about 400 miles off the comprehensive warranty then onto my 7 year/100,000 mile warranty. The HL drives nice, but I noticed (sometimes) when I am a at cruising speed then take my foot off the gas it is as if I hit a puddle of water. Meaning, it does not simply coast but seems to down shift or slow down a bit quicker (no foot on brake though). I was wondering if the transmission has that "main driver memory"? This was a rental vehicle.. If so, could I simply undo the battery for a few minutes and have it reset to factory defaults or does it need to be Re-flashed?

Like I say this only happens once in a while. Transmission shifts like it is supposed to, no slipping, delays or any sign of transmission failing. Just seems like a "bad" program or something.

typesix · 06-24-2010, 10:30 AM

Normal for recent Toyota vehicles, it will seem to drag till speed reaches 20-25 mph and then you will feel a release and the car will coast better. It's designed into the transmission.

***TrailDust*** · 06-24-2010, 10:54 AM

Still, that's a valid point about the HL being a rental vehicle. It wouldn't hurt to disconnect the battery and reset the computer so that it can relearn your driving patterns for mileage, shift points, etc.

caperforlife · 06-25-2010, 10:00 PM

Hi. Could somebody explain this driver memory further with respect to transmission shift points etc. I have not heard of this before. Thanks.

***RningOnFumes*** · 06-25-2010, 10:47 PM

Caper, if you're asking for an elaboration of TrailDust's posts:

Autos today have some inteligence in that they adapt to a driver. It's easiest if we use the broad extremes between a very agressive and a very cautious one. The tranny will adapt to the needs of the agressive driver by higher/longer, with the shift points at the upper end of the rpm power band. This allows for most power.

At the other end of the spectrum, you'll find the shift points sooner or more smooth as they may be based more on the speed the car is going since this driver just wants a smooth acceleration and is in no hurry.

Resetting the computer basically tells the car to relearn how to driver according to the driver's needs. It could relearn things on it's own, but it might take longer.

91TB78 · 06-26-2010, 11:33 AM

I've noticed the same thing,but mine is more part throttle to full throttle back to part throttle. The shifts can sometimes be a little jerky going from one gear to another. Not a big deal though.

Axxis8203 · 06-26-2010, 01:30 PM

i noticed this as well on my 08 camry and was told by the tech at the dealer that the newer toyotas also have fuel cutoffs designed to save gas when you have taken your foot off the gas and are coasting.

i understand what you mean though. my 08 camry is the only vehicle i have ever owned that decelerates when coasting down a 4-5% grade hill. you'll get used to it though...

caperforlife · 06-26-2010, 03:28 PM

Thanks Fumes for the tranny memory explanation. I bought mine used so I think I will try resetting the computer to learn my driving habits. Also, I felt the vehicle slowing down when coasting down steeper grades. This was my first 4wd vehicle so I thought it was slowing due to the extra mechanical drag of the drivetrain components but it sounds like it is part of the tranny programming. This must hurt the overall gas mileage though?

***TrailDust*** · 06-26-2010, 05:01 PM

Quote:

Originally Posted by caperforlife

Thanks Fumes for the tranny memory explanation. I bought mine used so I think I will try resetting the computer to learn my driving habits. Also, I felt the vehicle slowing down when coasting down steeper grades. This was my first 4wd vehicle so I thought it was slowing due to the extra mechanical drag of the drivetrain components but it sounds like it is part of the tranny programming. This must hurt the overall gas mileage though?

All depends on your driving style. If someone's going to be a leadfoot then the powertrain will be focused on high power output and high gas consumption, but if you take it mellow your mileage will benefit. As these guys know I am very mellow with my driving style--except off-road

--and I average 19/20 city and 27/28 highway.

91TB78 · 06-27-2010, 09:37 AM

Traildust, do you reset your ECU after every offroad romp? My wife and I drive mostly highway and get about 21/22 on hwy, but that's going 80+. Of course in town I enjoy the acceleration, so that may cause my shift points to be more aggressive.

***TrailDust*** · 06-27-2010, 01:59 PM

Quote:

Originally Posted by 91TB78

Traildust, do you reset your ECU after every offroad romp? My wife and I drive mostly highway and get about 21/22 on hwy, but that's going 80+. Of course in town I enjoy the acceleration, so that may cause my shift points to be more aggressive.

No, I don't. It's only ever reset when my battery has died, which has been twice now. Sounds like your highway mileage is close to what I get, which is about 28 MPG at 65, 26.5 MPG at 70, and 23 MPG at 80. For the most part off-road I tend to get what I get in the city.

lets456 · 06-29-2010, 10:22 AM

Undid my battery for 5 minutes and then redid and what a difference!! Much, much smoother on the down shift and up shift is better. I will report back over time and let you know if it stays "steady".