Help diagnose this thing, please?!?!

Let me start off by saying that I've read and participated in enough transmission complaint threads that I have NO desire to start another one. PLEASE, PLEASE do not turn this into yet another one.

I want to figure out what my transmission is doing so, MAYBE, I can have a better conversation with my service manager.

So, here's the deal: It jerks. It bucks. It surges. It shudders. It "clunks". It hesitates. Whatever you want to call it. I'll elaborate with this example, going 30-35 mph, S4 mode, trans in 4th gear, 1500 RPM, no change in pedal, flat road, you feel a random "jerk". It's subtle. Feels like you hit a small bump in the road. Sometimes passenger can feel it (wife comments on it), sometimes not. Almost feels like the truck "misses" or has a mis-fire. No change in RPM. I've watched the tach numerous times. No real rhyme or reason for it to happen and no consistency with which it happens. Sometimes it happens on a flat road. Sometimes, a slight rise will do it. Occasionally, it will do it while accelerating. Most of the time, it's just when you're at a constant speed. Doesn't seem to do it over 60 mph BUT I'm getting more used to it and I probably just miss it.

Dealership has checked fluid level manually and added "1/4 to 1/2 qt".

What makes this happen? Is it the torque converter unlocking/locking? Seems like it does it worse in 4th gear than any other BUT I've noticed it in 3 thru 6.

It's completely and totally random and the last time I took it to the dealer they couldn't reproduce it. I get it. It's so random that it's hard to predict and you'd have to spend an hour driving to really notice it.

So, what is it?

 

Sounds like a hard shift, which in a new truck/transmission would make me think that the fluid is low, meaning they either didn't fill it enough or lied about filling it. Either one wouldn't surprise me from a stealership. I'd get the fluid level checked at another dealership if you can and verify that the level is correct, seeing as how it's such a common issue on these trucks.

There was a TSB for the 2016's and the auto trans but I'm not sure if that extends to the 2017s.

 

https://www.tacomaworld.com/threads...ng-style-and-is-break-in-a-real-thing.409696/

This is my understanding of the auto transmission. I read somewhere that the new computer in these truck learn your driving habits. Which make the case as to why no one else can reproduce these shakes and shimmies of the tranny. They drive your truck different than you do.

 

This is a great point. Everyone should be doing the driving and have the tech take the passenger seat. Then you will know it happens with the tech there.

 

My Jeep was doing this, but the RPM would drop and then snap right back up. Turned out to be the crankshaft position sensor. Easy fix.

 

Low tranny fluid..!! Have it checked properly..! Do it yourself if you are able... Dealers are shitheads..!

 

Sounds like a good suspect to me. Don't know what RPM the converter locks/unlocks, but that would be interesting to find out.

That also makes sense, if you are just cruising. ANY fuel application at that RPM (if that's the unlock cusp) would activate it to avoid lugging the engine. The converter has to be unlocked to up or downshift.

 

Does it do it in "D"?

 

Yes.

 

In S4 does it do it with the ect button pushed? My guess is its the converter locking and unlocking.

 

To be really honest, I don't use ect much so I'm not 100% certain. I was lugging around some back roads near the lake a couple weeks ago and I think I had ect on and it did it several times in a row.

 

This definitely sounds like the TC is in lockup and is trying to come out. I bet if you bump the gas it'll downshift.

Anyway, this sounds like a side effect of them changing the programming so it holds gears better.

Mine does this too and I didn't notice until after the TSBs were applied. This is far less annoying than it shifting at the slightest load.

 

Manual trans trucks will produce a very similar symptom under load at relatively low RPM. In my case, using E0 91 Octane helps.

See this thread:

https://www.tacomaworld.com/threads/slight-miss.448072/

 

Mine does same thing can't stand it . Mine been going down hill after 1800 miles first TSB about 6000 miles second one.

 

I’ve seen faulty or failing CPS sensors give off those same symptoms, true story. Unfortunately, they have a habit of not turning on the MIL light and maybe hard to pinpoint until total failure.
But your issue could be anything and I seriously doubt the ATF lvl had/has anything to do with your issue.
For now at least, I would say your dealer(s) (try different ones) is best qualified to nail it, just write down as much as you can on when and how it goes down.

Best of luck
Cheers!

 

So, here's the deal: It jerks. It bucks. It surges. It shudders. It "clunks". It hesitates. Whatever you want to call it. I'll elaborate with this example, going 30-35 mph, S4 mode, trans in 4th gear, 1500 RPM, no change in pedal, flat road, you feel a random "jerk". It's subtle. Feels like you hit a small bump in the road. Sometimes passenger can feel it (wife comments on it), sometimes not. Almost feels like the truck "misses" or has a mis-fire. No change in RPM. I've watched the tach numerous times. No real rhyme or reason for it to happen and no consistency with which it happens. Sometimes it happens on a flat road. Sometimes, a slight rise will do it. Occasionally, it will do it while accelerating. Most of the time, it's just when you're at a constant speed. Doesn't seem to do it over 60 mph BUT I'm getting more used to it and I probably just miss it.

So I'm experiencing something very similar to neilbedwell except to say that it has only happened the last two days and seems like it is happening at approx. 60 mph and while pulling a hill. It is a "shudder" or brief "shimmy" with my kids likening it to when their bikes are out of adjustment and the chain is trying to decide which gear it actually wants to go into. I was thinking transmission slipping or something similar and will go check ATF level at this point from what others on this thread are saying. What else should i check and/or consider? Thanks to all who reply!