I just replaced my upper transmission mount on 08 TL-S 3 days ago and after driving it for 2 days noticed no issues, then today I noticed some vibrations while diving. The most noticeable vibration seemed to come around 40 mph while accelerating just before the transmission shifted, but I also noticed vibrations during acceleration when driving on the highway, these vibrations seemed to come at all different speeds. I did go with an aftermarket mount as I just cannot afford the OEM one at this moment. However on another note, I did not notice this vibrating issue until after I filled up with gas, and later upon trying to diagnose the issue while keeping the car in 3rd gear, I noticed that right around 3k rpms is when I felt the vibration the most and I swear I heard engine knock. I know its highly unlikely, but perhaps the gas was contaminated and the vibrations i was experiencing was from knocking, I did notice after driving the car later uphill that it seemed to be struggling some. I filled from pretty close to empty with 10 gals, burned off some on the highway then topped off with 5 gals of more 93 from a different gas station, but only drove a few miles home so I could not really tell if there was much improvement. It seemed that I was getting these vibes more so when accelerating gradually from a steady cruising speed. Would a new mount really cause driveline vibes at so many different speeds and RPM ranges? I would imagine it would be more noticeable at idle. Any thoughts on this would be greatly appreciated. Thanks!

 

well, double check your work.
then burn off the gas. and fill up with new gas.

by doing these two things, you can rule out one or the other.

as we have no way of telling on the internet, as we dont have the car in front of us.

 

Yeah its the mount... I guess with aftermarket you get what you pay for... and I'm paying for vibrations, but they do seem to be getting lighter as the mileage goes on.