My car is a 2006 E55 with 82,000 miles on it. It's in great shape.

Every time I lean hard on the car, I'd guess 3/4 throttle or better, the car hesitates on the 1-2 shift. That's the only time it does it, never on any other gear change, and never without the 1-2 shift. It runs flawlessly at all other times. I can only call it a hesitation, I don;t know how else to describe it. Essentially, it hiccups, your back stops being relentlessly pressed into the seatback for a moment, then it "catches" and your off like a freight train again. It's not a full out "fall on your face" moment, but it definitely hesitates or hiccups.

It's done it since the day I got it a few months ago, and the car has been on a STAR machine with an extremely experienced operator of the machine, and nothing flagged on it.

Any ideas, anyone?

Read here...https://mbworld.org/forums/w211-amg/...eleration.html

That doesn't sound like my issue. Mine happens only in the 1-2 shift, and it happens at WOT as well.

Doug- Start by replacing the electrical connector to the trans. You will surely find the o-rings leaking fluid into the harness. May not fix your problem but I've seen it fix similar, and more than likely you need a new one anyway.

Try resetting the transmission adaption settings and go from there. Mine will do this one moderate throttle (40-60%) 1-2nd shifts. It feels like the torque reduction/management system over does it a little. It doesn't bother me since my car does the "DSG Fart" sound and it's pretty cool sounding

Disconnect battery for about 10 mins and see if it helps.

I have this on stock and tuned tcu was this ever resolved?

Both my E55 without a TCU tune and my SL55 with TCU tune hesitate on the 1-2 shift at light throttle. It seems to improve as the car warms up. Both have a delay after a 2-3 full throttle shift before the acceleration resumes. I would love to try disconnecting the mechanical link to the throttle plate and replacing with a linkage/cable but leaving all the electronics in place. The ECU will still think it is controlling things but maybe bring control back to the right foot.