2021 OR transmission shudder/surging at speed

I have not experienced this. No hiccups at all with the tune.

Which specific tune do you have? Mine is LT 91/93

 

Mine is the slt regular tune. I had no surging/cut when it was stock. I was still 04B80 so the tsb update was applied at the same time. Now 04B81. I think I’m in the minority with this issue on kdmax.

 

For what it's worth, I notice the problem in ECT mode and also using S-mode. Just saw the S-mode suggestion, so want to drive it a lot more in S-mode, to quadruple check... but on first test, I didn't notice any change when using S-mode... still had the shudder.

 

It was confirmed that the shudder is there in Drive, ECT, and S-mode. It was said that it was a little less in ECT, but still very much there.

 

Was S3 used?

 

I asked @BlueTaco4x4 to get back in here.

 

Hey.

Thanks for the help. I was told that @BlueTaco4x4 traded for a Ram.

I was hoping for a fix or tune resolution here.

 

For what it’s worth, 93 didn’t have any effect on the issue for me. The shutter/stutter is still there, even with 93.

Also have noticed (as others have said) that it’s definitely more prevalent as it heats up. In the morning when it’s cool, on the first drive it’s much less noticeable. Then in the afternoon when it’s warmer and I’ve driven a while it’s much more pronounced.

I drove it a bit trying to really focus on the issue while trying some different things… It seems to always do it when just maintaining speed, and it’s subtle most of the time when you’re just maintaining speed… but then I noticed that I can get it to be more pronounced nearly every time if I first maintain speed then give it just the tiniest bit of gas (like not enough to even really register on the RPMs… literally just barely a little more pressure on the pedal), and it’ll right away start to stutter more pronounced. I paid really close attention to the rpms as well… previously I had never noticed the gauge bouncing or fluttering or anything… but this time I kept watching it closely and sometimes right after the stuttering, the gauge would indeed flutter up then down, just a tiny bit… subtle enough that you could easily miss it if you aren’t just staring at the gauge (which is hard to do when driving…).

Anyway, just some more info.

 

Still think its a converter issue for these transmissions. My buddies 2019 is really noticeable while some apparently are not. Once my 2020 truck began breaking in the slight shutter disappeared with more miles...now at 10k miles its completely gone, very smooth. Doesn't matter what grade fuel used, but 87 is by far best in this truck. Imo, if your still experiencing this problem after break in...no matter what you try, its always going to be there. I think its just a characteristic of these transmissions.

 

I took mine in for the fuel pump recall and mentioned this. Service adviser was very familiar with it. Said he had a 17, he ended up getting rid of it for a 2nd gen and couldn't be happier. Said they get lots of complaints.

There was an updated flash for the transmission for my truck, FWIW, and they flashed it. Can't complain about the ride home, we'll see. I did start putting premium in it so I'm not sure if it is fixed which it will be, but if it runs better now I may go back to regular 87 again to see if it returns. Hell you throw a new fuel pump into the mix and I have three variables.

It's a shame what Toyota did to these trucks, purely for the sake of the EPA testing. I can't bring myself to spend another 1k on a tune just to make it run right, but maybe I will if this doesn't fix it. I have 16k miles on a 19 purchased in May 2019.

 

Frankly, I don't believe the shit show is purely for the sake of EPA testing. I am getting better mpg and better performance tuned than stock. Toyota just half assed it when it came to tuning the transmission. The fact that we have people with no previous tuning experience taking vf Tuner and making better performing tunes without sacrificing mpg speaks volumes.

 

Latest update. Took my 2020 SR5 in again to try to get them to address the shudder. I wrote up a really detailed breakdown of what was happening, plus gave steps to replicate the shudder (I found that if you maintain speed — most noticeable at highway speeds — then give it just the slightest gas, it'll do the shudder nearly every time. Of course it also does it randomly when just maintaining speed, to varying degrees of harshness). This time around I specifically called out "torque converter shudder," made sure that was noted in the file, and even called out others who have had to take it all the way up to corporate, to ultimately have the torque converter replaced. When the called back later in the day, they said they started a case with Toyota, their quality control specialist and FTS came out and test drove the vehicle. They said they "couldn't duplicated the described shudder condition." They said to "note that subtle vibrations can be expected from the engine at certain RPMs and throttle input due to atkinson cycle operation," and that "it is working as designed."

Their answer confuses me a little... because either they couldn't duplicate the shudder (which they said), or the shudder is normal and it's working as designed (which they also said).

Not sure where to take it from here. There's most definitely a noticeable shudder, and if that's working as designed, that's pretty unfortunate.

 

Bet you got a nice smoke ring on your sphincter.

 

For shits and giggles, try high octane in one tank.

When I had my fuel pump recall done, and they re-flashed my ECU with a TSB designed to address this issue, I also filled up with a tank of premium. The thing drove better--but I'd made three changes.

I continued to put premium in it.

I just filled up with 87 octane no-ethanol fuel, and some of this shudder/jitteryness came back.

People around here swear you only need 87, and maybe that's true in some cases. But I'm going to fill up next time with 91/93 and see how it goes again.

 

I'll second that on the higher octane. There is no logical reasoning behind it but there is a noticeable difference when I switch. The more I drive it, the better it gets as well. I've learned to anticipate the shudder and go ahead and get my foot into it so it will downshift and, over time, that has trained the transmission to shift earlier. I gave up on expecting perfection because ultimately I love my truck and whenever I find someone in my area with the OVTune I'm jumping on it.

 

I did indeed try a full tank of high octane and unfortunately still had the shudder just as noticeable.

Mine hasn’t come up for the fuel pump recall, but I’m curious about that. I’m also checking with the dealership on any TSBs. I’ve heard mixed results, but Im willing to try pretty much anything. I love the truck. Just want something to work.

I’m not sure about being able to anticipate the shudder. On acceleration, I could see that. For me though, it does it the worst just randomly when maintaining speed — humming along smooth and then out of the blue it feels like it hiccups randomly.

 

There is newer TSB software for the 2020 and 2021 ATs. New ECU IDs 04B82 and 04C21. We have the CUWs, but not actual TSB yet. The only reported change so far was that Crawl Control was now working properly on a 2020.

 

i run the rear tires no higher than than 32...any higher and it turns into a pogo stick with nothing in the bed

 

almost sounds like an issue with the electronic throttle not giving smooth inputs.

 

That was one of my guesses, but the regional techs found nothing. I can only assume that @splitbolt had it right about the torque converter issues.