TRNW-2: Chevy Active Fuel Management Killing 6L80's?

[Tony's Autoworks]

Hello group,

Wanted to get an opinion of what I have seen over the last 3 months. I
have rebuilt six 6L80/6L90 and have had a few other vehicles come in
the door with similar problems that I will explain in a moment. Of the
6 I rebuilt, all had 4-5-6 clutch stacks completely burnt and 3 of the
6 had pumps that were not reusable. Of the 6, 2 of them were towed in
with no movement. Just finished the 2nd of the two yesterday and
completed a test drive for the new techem to adapt. But noticed both
towed in units having some issues but could not determine the cause
until now. After a certain amount of time test driving I'm noticing
rpm fluctuations and an intermittent shudder noise on the most recent
unit. Checking scan tool data the TCC is applying and no TCC RPM slip
is occurring when the shudder happens. I noticed the same issues on
the last unit but NO shudder until today the customer told me he
experienced it and I just test drove to confirm.

I also have a customer with a 2015 Suburban that had a transmission
installed a few weeks prior from a different city and started
experiencing the shudder issue. He thought maybe he had a defective
torque converter. I noticed the shudder in the Suburban sounded
different from the shudder in the silverados so I thought maybe the
converter was defective. The suburban customer took the vehicle to the
dealership and they diagnosed the Active Fuel Management causing the
shudder when the system is activated and recommended a new engine or
complete replacement of all AFM components.

I took my recent rebuild on another test drive and with the traction
control off (a friend from the chevy dealer advised this test) and now
there are no RPM fluctuations and no shudder. Same with the other unit
with similar issues.

So now I have 2 units that have been rebuilt that looks like the
Cylinder displacement may have been the cause of failure? My friend at
the Chevy dealer says they are seeing a lot of these units come in and
if they catch them in time they can save the transmissions. And most
are replacing the engine rather than components.

My question is this: Unless there are engine codes to know that the
Cylinder displacement is an issue, how do we sell the build?
Especially if the vehicle can not be test driven. I have 2 customers
that have spent money on rebuilt units but now are looking at twice as
much to fix the engine issues.

I'm sure this topic has come up before and I guess I missed the memo.
Just curious of your opinion and what have you done to diagnose this
issue before selling a build.

Thanks for reading,
Tony