2016 ATS Rumbling at low throttle

[coolnesss]

2016 ATS Coupe V6 Automatic had what felt like a driveline rumble when doing about 50mph up, and when I gave it a little throttle to speed up a little bit - not enough to provoke a gear change.  It almost felt like the transmission was searching for a new gear - but that's just conjecture.

Then I took a road trip for 200 miles, mostly at fairly high speeds most of the way - 70-120 - and it seems like the rumble went away.

There's a TSB on the condition attached.

Is it possible that the high-speed driving cleared this up?  The dealer, of course, wanted to sell me new tires.

 

 

[BodybyFisher]

I was thinking tires also.

You checked pressure, and stagger is ok?

Maybe a long trip ran them harder?

See any roughness in the tread area?

[coolnesss]

Mike, thanks for your note - but it's a mechanical rumble/vibration.  It reacts to a slight throttle application at speed - at various speeds from 40 or so all the way up to about 70 or so.  A good push on the accelerator at the same speeds doesn't produce the rumble.  It's a slight application of more throttle.   And it fits the description in the TSB perfectly.

The tires are fine, pressures are all at spec.  

[BodybyFisher]

4 hours ago, coolnesss said:

Mike, thanks for your note - but it's a mechanical rumble/vibration.  It reacts to a slight throttle application at speed - at various speeds from 40 or so all the way up to about 70 or so.  A good push on the accelerator at the same speeds doesn't produce the rumble.  It's a slight application of more throttle.   And it fits the description in the TSB perfectly.

The tires are fine, pressures are all at spec.  

Very interesting that a tranny fluid change would make such a difference.  Please report back your experience with the fluid change.  Could the factory fill have an inferior fluid?