coolcow

I don't know how many of you ever experience any abrupt shift around 35mph. It happens when I step off gas and break, and let my car slow down from 40mph or so. Then try to accelerate again around 35mph and, suddenly, the shock comes. I believe this happens at the point between 3rd and 4th gear and the computer is confused about which gear to use.

I also tried a few loaner cars. At least one car has the same issue while others shift just fine.

weinrdog

I have/had that happen too, but it went away after my 10K service. Don't know what they did to get rid of it, but am glad they did - of course it could come back, but hasn't for the last 2K miles. It's really annoying in slow and go traffic.

I also got about a 1.5K RPM jump too before it engaged, but wouldn't notice it until the shift shock/lurch hit.
I thought it was more gears 4 - 5, but didn't count. A heavier foot seemed to help the tranny decide quicker which gear it should pick & then re-shift if necessary within a few seconds.

ESDragon

Shift shock?? Do you mean a flare? Thats when your RPM goes straight up between 2k - 4k rpms? If so, that's a common issue with the ES.

coolcow

This one is different. It seems to happen when you try to accelerate right at the gear shift point. The tranny is just confused what to do. As weinrdog, it becomes annoying in stop and go traffic.

Pheonix

It's not the cars fault.
What happens is the control logic changes the fluid pressure in the valve body, and swaps shift solenoids to change the gear. When you floor the pedal, you're telling the ECU that you want alot of torque output.
The ECU is programmed to apply more fluid pressure inside the valve body. The end-result of that the movements inside the transmission happens faster. What you are experiancing is that the higher fluid pressure holds the clutches together with much more force - keeping them from slipping. It's a good thing...
Doesn't matter if it's an Automatic transmission from 1950, or 2007. You can re-create your problem on every A/T ever manufactured to some degree regardless of throttle pedal, vacuum, A hybrid of both, or fully electronic transmission logic.


Not helping you is that when applying more throttle during the shift, the ECU had already set a valve body pressure and the valve body & gear change is in progress. Now that you've added more load to the programming, the now raised pressure takes what was previously happening & speeds it up part-way through the previous process.








In this case, unlike the flare issue. The problem here is how you're driving the vehicle. Adjust your driving to suite. You found the point where electronic throttle, and transmission logic are not quite so hot. So avoid it.

NoiseFree

What's with this flooring the gas pedal that I see here from time to time?
I've never floored my gas pedal in over 30 years of driving.
Is it something I should try out?

weinrdog

Phoenix - It's MUCH worse of an rev-up & impact when driving with a soft foot. I drove manuals for 23 of the last 26 years & am used to follow traffic using just the gas pedal with a soft foot to keep distance in traffic.

In the ES, driving with a soft foot seems to delay the engagement enough for the engine to spool up to 3.5K - 4K RPM (from 1.5K), then the tranny will engage with a lurch. The engine is quiet enough that you don't realize it's happening until you get 'kicked in the rear' by the tranny engaging.

By being just a little heavier on the gas when I want to go, the tranny seemed to engage a little quicker & I wouldn't get the large kick.

The common denominator for this is slowing gently (off the gas only) in the 35 - 40 MPH range and then wanting to accelerate just slightly.

As I said, the dealer did something during the 10K service that has stopped the issue for me, but there was nothing special/extra listed on the service invoice.

coolcow

weinrdog - Your description exactly matches my experience. Did you mention this to your dealer at the 10K service so that they might do something to fix that?

Phoenix - if this is what you described, I haven't experienced this kind of lurch for all the other cars I drove...

ES350Bob

Similar in the LS as well.

https://www.clublexus.com/forums/sho...d.php?t=278429

MD350

This has happened to me less than 5 times in 12K miles. I guess it is another standard feature that comes with the ES.

weinrdog

Near the end of my 10K service, I mentioned 3 things that I wanted to schedule a follow-up appointment to address. They may have done something to address it, but it wasn't listed on the service repair receipt. (They have fixed the other (minor) issues too).

cip

If the dealer 'did something" but there was nothing listed on the invoice is it possible the something was as simple as removing battery power to your car during this time? If so that usually resets the 'learning' transmission back to default so now it's relearning your driving style.

On my car it's as simple as removing the ECU fuse for 10 seconds. After putting it back in, I beat the spank out of the car for a couple minutes. The trans responds quicker & holds shifts a bit longer.... of course it learns that I don't always drive like that so I have to do that every few months or so.

I know we're talking different cars here but any 'learning' ECU will respond similarly