sounds like the car is hunting for gears on that slowdown. If you accelerate from a stop, you will notice that your car shifts 4 times into 5th gear, then after a few more seconds, your RPM's will drop a little more, as if it was shifting into a 6th gear. This is the transmission locking up the gear.

 

It does that on tiptronic porsches too.

 

That is an interesting question. My cousin's 5AT sedan drops little over a 1000 rpm when going about 70 mph. But my 6th gear is over 2000 when i go about the same speed? Is there a cruising gear or somethiing like that on 5ATs for gas saving puposes????

 

i didn't notice it until i got a high flow cat, whenever it does that i get this exhaust tone like a pop sound, like engine is dying in middle of acceleration, i thought there was a leak or something, but later realized my other auto car do that too, only no noise.

 

It sort of feels like it is shifting, like a variable speed "gear", i have no idea what causes it.

 

To me, it feels similar to a manual transmission car downshifting - like you push in the clutch, downshift, and then rev-match and release, only much slower than you would complete the process if you were actually rowing a manual.

I think it's a normal function associated with the rev-matching capability built into this tranny. It's an interesting sensation, but it's so consisitent that I have written it off as a non-issue. It's never caused a hiccup or delay in my ability to accelerate, nor have I experienced any jerkiness when getting back into the gas from a coast.

If it's any consolation, the M35 did exactly the same thing, as did the DEMO G35 I drove prior to my purchase.

I use the manu-matic more and more these days. I'm really getting used to the shift-points and I like the controllability it gives me. There is almost no delay in this tranny - I really like it.

 

Maybe this will shed some light? It talks about the basics of automatics, as well as the torque converter and the torque converter lockup process.