Auto transmission shifting hard/irregular

Hello everyone,
I have a 2007 Tacoma 4.0L V6. I was having issues shifting into reverse and other small irregularities with the transmission so I changed out the transmission fluid around 2 years ago and honestly didn't read enough into it to realize how huge of a task that was until I was already balls deep in it. So I did my best to read the temp properly and ensure the correct amount of fluid going in- that was a fucking nightmare. Ever since then it's still been a little wonky but kinda evened itself out again.
Well recently in the past couple of months it's been shifting weird again but it's getting progressively worse. I'll be driving down the road and it'll shift at odd times and kind of lurch and other times feels like it drops into gear. The RPMs don't shoot up so it's not falling out of gear completely but it's not transitioning smoothly.

Is this something that a sensor might be causing or a fluid/filter issue?
Any info or direction would be greatly appreciated so I can start researching the correct thing (and not tear into something I don't need to fuck with) and acquiring the materials needed to fix this by myself (hopefully)

 

Considering your experience with a transmission fluid change.

I would urge you to take the truck to a transmission shop or to Toyota. Don't guess at what is wrong, just describe the symptoms and the work you did 2 years ago.

 

Knute,
Yeah I was hoping to avoid that but that's probably the route I will take. Thanks for taking the time to read and respond!

 

Frankly OP, I suspect it may be low on fluid.

The process is fairly simple, although a bit ticky to engage. There is a detailed description on how to get the truck into Temp Check Mode. Be aware, there are 2 plugs on the bottom of the transmission pan. One is drain, the other is Check. I believe the Check plug has the word "CHECK" stamped on it. Best visible with a flashlight, may need a rag to clean it a bit.

My experience, its best to overfill the transmission by about a quart. Get into Temp Check Mode, wait for the dash light. Crawl under, remove Check plug, drain off the excess.

Follow the procedure.

 

Gotta start with fluid level and then see where you're at

 

Lurching and dropping into gear sounds like a fluid level check is needed.
Does it do it worse in turns, on hills, or under “hard” acceleration?
If so, defines check the level.

BTW, if you ever do another fluid change.
Do it on a cool engine, measure what comes out, and at a minimum put that back in it.
At least you know you are “close”. Obviously, you can’t so that now. Because you don’t know it the fluid level is correct.

And I agree, the check procedure is a joke.
No reason it should be that complicated.
Still don’t know why they felt there wasn’t a need for a dipstick?

 

Don’t skip on your transmission. If it’s acting up, have it checked out by someone that’s competent.

 

I completed the entire procedure with the whole temp check mode and waited for fluid to come out of the check plug. I did the entire thing multiple times because I was doubting myself and still wasn't getting fluid out of the check port. I thought I overfilled it but never got fluid coming out. I definitely put more in than I got out of it.

But yeah I do not understand why they had to make this so damn complicated. A dipstick would've been nice.

I'll be taking it in for a diagnostic so I can get a second opinion/confirmation from people that know way more than I do.
Thanks everyone

 

Ok.....you did the check method but no fluid came out of the CHECK plug.

This suggests the transmission is low on fluid.

FWIW, when I did a fluid/filter change on mine. I drained about 3 quarts. After all was said and done, I had added the 3 quarts plus 3.5 quarts more before fluid dribbled from the CHECK plug. My transmission was roughly 3.5 quarts low when I began. It did exhibit hard shifts. After the maintenance, the shifts are so smooth I need to watch the Tachometer to notice the shift points.

 

Just put some more fluid in it until it comes out the check hole in a healthy stream. Honestly it's not that hard

Don't worry about the check mode light. All you need is level ground at operating temp, engine running. Don't need to drain anything, just pull the little check plug and the big 24 mm fill plug up on the side. Get one of those plunger fluid transfer tools and a few qts of WS. Start feeding it until it runs out the check tube. Cycle it through the gears, watch it drip for a minute, add some more fluid just to see it drain out if you want. Leave the engine running the whole time, it won't hurt anything