Automatic transmission jumping out of gear?

My ‘19 V6 AT just started doing something weird.

On high RPM S-mode upshifts, it feels like it’s jumping out of gear for a moment before clunking (somewhat violently) into the next gear.

Happened 3 times yesterday, usually going from 3rd to 4th (maybe 4-5 too? Can’t recall exactly).

Almost feels like I’m hitting neutral, which doesn’t make sense. There’s no way to do that when the stick is to the left on S-mode. Or is there…?

In case it matters (overheating trans?), this was during a long, all-day high speed drive (had to get somewhere far in a short amount of time). Fair amount of flooring it to get around slow moving traffic and using the 3.5 for all it’s worth.

The issue didn’t occur when leaving it in D and still driving hard.

Truck has 75k miles. It’s tuned, which I know adjusts the trans shift points…

Any ideas? Does it need a trans flush? Is it ready to blow?

Thanks for any help.

 

Define, "High RPM" please.

 

A little below redline, probably 5500 or so. Wasn’t hitting fuel cut.

FWIW, the tune I have raises the redline to 6500 RPM, but I never push it that high. But I did spend a lot of time in the 4000-5000 range throughout the day.

Edit to add, I’m on 35s and 5.29 gears.

 

it was probably hitting the fuel cut. there is a slight delay when using s-mode to change gears and it doesn't shift instantly. if you wait too late to shift into the next gear this is what happens.

 

I would guess that what you felt was simply the transmission trying its best to cope with being shifted at a point where it should not have been shifted.

 

Trying to use S-mode as an autostick while redlining is a little bit out of the transmission's operating parameters. Do you hate your truck or something?

 

I had the same issue with the KDmax 6 tune, truck would violently shift and make a loud noise. once I upgraded to KDmax 7 that issue never happened again. I believe it’s a know issue with that version. PM paparee

 

This is happening because S mode is simply a top gear selector. Doesn't matter that you're shifting from 3-4, the truck will stay in 3rd gear until it decides to go to 4th on hard acceleration. If you just so happened to "shift" to 4th around the same time as the truck would have done it, it will give you the illusion you're shifting it. Try accelerating hard and shifting from 3-4-5-6 and you'll see it's not doing anything unless it gets close to redline on any of those gears.

While upshifting will mostly do nothing on the Tacoma, the downshifting will appear to work well if you're going downhill or driving at a higher RPM simply because you're forcing it to a gear limit.

 

Might not be related to your AT issue but at 75t mikes, it’s time for a fluid change

 

Ive learned to give it the “upshift” input well before I actually want it to shift. I’m not pushing the stick forward and expecting it to shift right away. Again, I have 75k miles of experience with this truck.

If I roll off the gas slightly after giving the upshift input, the trans will “get the hint” and upshift before redline.

Again, this is not the truck hitting fuel cut. I’ve done that once or twice and it’s a totally different thing.

 

This makes sense. I hope that’s all it is. But, it’s strange that it just started happening yesterday, as I operate the trans like an auto stick from time to time. Is that a big nono on these trucks?

 

I think others have already said it best; the S-mode isn't a paddleshifter - its intent is to be used as a top gear selection. My best guess is there's some sort of conflict with the truck wanting to shift, but being told not to, then being "given permission" to shift when its being driven a little outside of those "normal" operating parameters.

 

You may not be hurting anything necessarily, although it seems like you're making your truck work harder than it needs to at times. The important thing to understand is the s-mode is just a top gear limiter. Its intent is for towing, and keeping the trans out of the overdrive gears, to alleviate overheating, or to be used for engine braking.

 

Thanks for the input, I’ll adjust my driving technique. And get a trans flush.

I knew I should’ve gotten the manual…

 

The torque converter does partial-slip in 3rd, but to shift to 4th, it has go back to full slip. If the timing is off (possibly from poor condition or low level fluid), it will do a minor shift flare. From 4th to 5th, the torque converter also unlocks from full lock, but usually the fuel flow is cut in time to prevent the shift flare.

If you spend a lot of time at 5500 rpm in 2nd and 3rd gear, you're slipping the converter constantly and heating up the fluid. If the fluid heats up too much, it starts breaking down at an accelerated rate. It sucks, but these trucks weren't designed to be driven at high speeds in low gears for extended periods of time, even while towing. The degraded fluid will expose weak points in the transmission hardware, and for Toyota's 6 speed autos, the 3-4 shift solenoid is historically the weakest leak, and it's common for 07-09 V6 Camrys and Avalons as well as ES350s to experience shift flares from 3-4 when the fluid gets old and broken down.

If you're experiencing a minor shift flare, draining and refilling the fluid once or twice will probably help. Ensuring the fluid is at the correct level is also a must before taking any other action. As long as the shift flare is minor, the transmission isn't going to explode. Toyota's that start exhibiting the shift flare typically last several years after the symptom initially presents.

The fact that this only happens in S mode and not in D tells me this is unlikely to be a purely mechanical issue. You may want to bring this up with your tuner. Possibly revert to stock and see if the issue improves or worsens.

 

There are safeguards where you can't really do anything to hurt the thing. You can even move the lever to Reverse while cruising down the highway and all it will happen is the reverse cam will come on.

 

Phenomenal insight, thank you for this.

 

Ok, I’ve had this happen towing a trailer under heavy and load- I had my obd2 hooked up monitoring once. And it basically seems to be the torque converter having extreme indesicion on what the fuck it wants. No harm done so far. Seems to have stopped doing it after a retune.

 

It just did it again last night on my way home from work, but this time in D, as opposed to an auto-stick upshift in S mode. I’ve stopped using S mode altogether since this started happening the other day.

Happened on hard acceleration at highway speed, again in D. On the 3-4 upshift around 5k RPM (wasn’t looking at the tach so not exactly sure), it feels like it goes to neutral, revs to the moon for a split second then BANGS violently back into gear as it goes to 4th.

Feels like it’s going to snap a u joint or ring and pinion if this happens any more.

Im barely going to drive the truck at all until I can get this dealt with. I was going to get the trans fluid changed in the next few days but I fear this could be worse than just degraded fluid.

I looked up “shift flare” on YouTube and the videos are nowhere near as bad as this. Just a slight rise in RPM as they upshift. This is like hitting N then banging back into D.

I have a long trek through UT happening in 5 weeks…should I be looking at a new trans in the meantime…??

Thanks again for any expert insight.

 

Sounds like you're low on transmission fluid to me......

You do realize you're beating your truck to death driving at that rpm and shifting like that, right?