I just purchased a 2010 Acura TSX V6 and I've been noticing a strange lurching feeling from the transmission when decelerating at around 40 mph. I would be driving faster than 40 mph, I let my foot off the gas pedal and allow the car to slow down without braking, right around 40 mph it kind of brakes itself. Does anyone know what this is?

 

The car does some automatic compression (engine) braking when you let off the gas under certain conditions. If annoying, I hit the shift paddle to make it shift.

 

From the way you explain it sounds like your car is downshifting and engine braking as a result but at 40 mph my TSX just stays in 4th gear. Not sure why yours would downshift if you're only cruising at 40 mph.

 

I have an 2009 TSX Auto Base with 117,XXX miles on it. I recently started noticing the same issue as you chamberlain. I was due for an oil change and a transmission fluid flush/change which I did today and after doing so the problem still remains. When i do go past 40mph and i let off the gas it slows down which never used to do that. Im going to give it a couple days and see if the fluid change/flush does anything.

Cheers