Whether in manual or automatic mode, in 2nd gear, light throttle, light acceleration, the engine drops about 200 rpm at about 2200 rpm, every time, for months now.

Some time ago I had this looked at by a Porsche independent shop amongst other things, they said they test drove it, they said the transmission shifts fine, I said "really?, ok" and let it go.

Is this a "thing", is it a torque converter lockup valve closing by design because of how the transmission is programmed to start in 2nd when warm... or is my car... "special" and an impending grenade?

 

Based on what you're stating in the first sentence, that is NOT normal. These cars do start in 2nd gear, but dropping to 200 rpm when it's accelerating at 2200 rpm is definitely not right.... that's like almost stalled out. Normal idle is around 750 rpm. Is the problem just the tach or do you actually feel the engine is about to stall out?

I'm surprised anyone that test drove it would say it's perfectly fine unless they couldn't reproduce the problem.

Take some video and repost.

 

I think the OP is saying it drops BY 200 rpm.
Apologies if I’ve got that wrong.
OP, the Tiptronic can be sensitive to gear oil going out of shear, although this usually results in slip/higher rpm. Have you change both the gearbox oil and it’s filter recently? If not, it may be worth considering.

 

No, I said "about" 200 rpm, it doesn't stall the engine.

I don't know why I put transmission in there though, I meant engine rpm.

 

Seems like the next step. This car drives completely normal except for this little "quirk".It never varies, always does it, which is why I'm wondering if it's a lockup valve or something.

The independent Porsche mech quoted me about $2k for a transmission flush ("we can do that if you want...") and water pump replacement about a year ago.

I've run this car to redline from 2nd to 3rd gear quite a bit in auto and manual and then into 4th (not redline :lol ), other than this quirk it operates completely normal, doesn't seem to "slip" anywhere to redline in any gear, been like this for the almost 5,000m I've put on it.