I drive a 5AT 05 TL, and if i ever go into the sport mode(all the time) and have the gear in 2nd at about 20 mph and depress the pedal about half way there will be a really bad vibration in the whole car. This also happen in 3rd gear at 20mph, with VSA off or on the vibration is just as bad. This includes being in automatic and trying to make the same situation occur. Its kinda freaking me out cause its been happening i just never thought about it until now.

Could it be a clutch or tranny failure?

Thanks guys!

 

Replace the 3rd and 4th gear transmission pressure switch.

 

yeah, you should replace the tranny fluid and pressure switches. I use Redline D4 and have had great results with it.

 

weird! my post disappeared and turned into a "thank you" to dwb

Anyhow. The pressure switches will do nothing for a vibration. they are also for the 2-3 shift and 3-4 shift only. I dont know about your 2nd gear vibration, but 3rd gear at 20mph and trying to accelerate will lug the engine causing a vibration. You say this only happens in sport shift? could be the engine lugging as your trying to accelerate in a gear you should not be in. motor mounts or a CV joint.

 

Well i just had my tranny mounts and motor mounts replaced about 10K miles ago. But i will look into the CV joint as well as the others mentioned!
But this vibration even happens in auto, as long as the system doesnt automatically downshift.