I purchased my 2007 TL 3.2 about a year ago. It quickly began to experience rough shifting from 1st > 2nd, 2nd > 3rd, etc. It it violently jerks the most in the shift from 1st > 2nd gear with decreasing intensity as the gears go up. Sometimes it will downshift rough into 1st gear when slowing down.
I have done quite a bit of reading and repairing over the past year since I bought it in an attempt to fix this problem. I have already:

Replaced all 3 clutch pressure switches (2x 28600-RKE-004, 1x 28610-RKE-004)
3x3 drain and refill using HONDA ATF-DW1
Replaced all motor and transmission mounts, which were destroyed, with OEM mounts

After doing each of these I have noticed no change in the shifting of the transmission for better or worse. As I've said it's been ongoing for about a year with no improvement or worsening. There are no codes detected by OBD scanner. I am at a loss here.
I have been told that this part could also be the culprit to this problem:

28250-RDK-014

Does anyone have any idea if this solenoid could indeed be the causes of the rough shifting? I want to know before I spend $300+ to replace it to no avail. Or will this problem just require a complete rebuild or new transmission?

Thanks.

 

Try reseting the trans computer super simple and could really make a difference, the video below should explain how to do this I know it works on my 2004 tl im sure it would on an 07 as well

 

I've tried this at least 3 times in the past with no change, I neglected to include that in the OP. I should also add that the shifts aren't as hard if I accelerate quickly. It shifts the hardest when the rpms are slowly creeping up. If I give it a lot of gas from a stop, the shift into 2nd is much smoother, but still noticeably rough.

 

Did you torque all the mounts to spec? I replaced one and did not went back and re torqued it and noticed it was a lot more smooth while shifting and putting the car into gear.

 

there is a DIY on how to clean the dual linear solenoids (part number in your post) that might help

 

The mounts were replaced by a mechanic shop, I don't know if they were torqued to spec, but the shifting was equally rough when they were the original broken mounts.

I'll look into cleaning it, thanks. I noticed that this solenoid is also dirtier than the single linear solenoid on top, do you think fluid could be leaking out of it causing rough shifts?