2021 OR transmission shudder/surging at speed

Maybe; maybe not...
Could be: the SLU solenoid(tcc pressure), SLT solenoid(main pressure), associated valve body fluid circuits...
https://gearsmagazine.com/magazine/...ft-quality-issues-in-toyotas-six-speed-units/

 

If the regional tech ran those diagnostics, the issue should have been found. As is, they just sent @BlueTaco4x4 on his way.

I like the leak idea in the first article better.

In either case, it sounds like there might not be a why to tune this out?

 

Are you experiencing and logging this using D?
Ever experiment with S-mode?

How'd you get 10hz?

 

Yes. We did not try ECT or S-mode. Nothing from @BlueTaco4x4 since the post suggesting ECT. I will text him.


It is an estimated 10hz. Low frequency and constant at different speeds.

 

@splitbolt

It was confirmed that there is shuddering in S-mode. ECT will get confirmed later today.


Also, from my newbie view, there is no Slip Lock in 6th gear. Just Unlocked and Locked. We were definitely in 6th and getting vibes.

 

It could be how these trucks with the automatic are driven from the get-go. Mine has been only driven by myself the entire time owned so far. I do agree theres way too much tech now in these trucks that wouldn't break my heart if it was no longer there.

 

Seen this?
https://www.scribd.com/document/468095057/DESCRIPTION-TRANSMISSION-TRANSAXLE-AWR6B45

 

Sorry, but I need more of a clue there. It looks helpful, but then I don't know what for.


Just a note that the OP's Taco is a 2021 DCLB with about 3k on the ODO.

 

Technical paper on the AC60.
It has the full lock schedule and slip-control strategy.

 

S3 or lower should confirm or eliminate the torque converter.

 

Ah! I can see that info in the tuning software.

The big issues in my mind are:

-- Is there a clear way of determining the issue?
-- Am I capable enough to do it and do it quickly as the OP is at the other end of the Seattle region?
-- Is the issue tuneable or is it hardware?

I am noticing a lot of 2021s coming up with this issue.​

 

I sort of agree because those gears don't lock. It is certainly felt at 4th and up, but when the Fusion app is reporting SLU and Lock.


The only problem there, for the OP, is if we confirm a TC HW issue, he needs to hammer that home.

 

That's what one of those articles I linked to alluded to... You don't necessarily have to have complete hardware failure; a hardware performance failure can affect things, but remain undetectable by the software.

 

What value(s) are you reading for SLU?
It sounds like "ON" and "OFF", but SLU should be a pwm controlled solenoid...
No duty cycles?

 

The TC lock PIDs were from a copied OBD Fusion dashboard that were 1 or 0.

Like I said, I messed up and didn't try AT logging in TS. I don't even know the options there yet as I do not have an AT to mess with.

 

Yes. I saw that, but I guess I'm looking for the idiot's guide (MT drive) diagnostic course, or is it just telling the OP to live at the dealer until they throw a TC at it.

 

First thing I'd do, is confirm fluid level.

I've noticed an uptick in converter replacements lately. Not enough to be a thing, but noticeable. So, they are getting replaced...

 

Thanks!

I will pass that on. @BlueTaco4x4 should be able to do that.

Interesting. Maybe some batch issues with that input shaft clearance? I know that it popped up on the 2019s and @OVTune was able to fix some with a special tune.

The Camry TSB that was posted earlier in this thread was great. Getting the dealer over the ledge will be the key?

 

KDMAX tune solved this issue for me. I'm running the 91/93 octane pack. Truck runs and drives as it should. Would highly recommend.

 

Interesting read. I had my truck updated and kdmax put on and now it seems as if it’s a fuel cut issue. Almost reminds me of running too much boost and having my sti hitting fuel cut and coming back. Only does it under light throttle loaded scenarios. Completely clears up after 3500 and the truck makes good power. Any chance it’s this garbage Atkinson cycle under load?