I think this thread is dead as fuck but whatever, still gonna reply. If this is all redundant and is all common knowledge that I'm repeating, my apologies.
So, I found this: http://forums.vwvortex.com/showthread.php?6881579-Why-you-should-keep-the-N249&p=84617263&viewfull=1#post84617263
It's the original post for all my gathered information outside the FR.
I also condensed it into a pdf spread so if the pics ever die, it's on hand if anyone ever wants it. I understand how it operates and how it can be applied to an eDV (eSUV) for the most part. I'm still messing around with it so I don't quite fully know what all the parameters are capable of yet. I will find out though.
Ok, here we go:
I outfitted the TFSI DV to my 1.8t, which to my knowledge can be done also to the 2.7t (a pair of DV's and n249s -->2 eDV's) which means this mod can be for the s4 guys too. (aside from the difference in software) It just makes a hell of a lot of sense to me because you can now monitor exactly and precisely when your DV opens and closes instead of relying on a partial electric signal and a partial pneumatic signal, where you cannot record the pneumatic signal in a log.
So as most of you know, in ME7.5 B_ldsua (DV actuation) is set true by either B_ldsuas or B_ldsuad. B_ldsua WILL follow B_ldsuas over B_ldsuad if both are set true or false at separate, conflicting times. I found that out through experimentation. I used this to my advantage as B_ldsuas is much more of a safe option. It's conditions set to true the majority of times and resets the flip-flop only under certain conditions. This way, your turbo is always bypassed unless you're under WOT (under the tt225 SVDLDUVS values, all over 1). This gave me a chance to truly play around with the main operating condition- B_ldsuad whilst B_ldsuas remained my safety net.
The n249's main operation is B_ldsuad, this is considered MAIN because under most files, B_ldsuas is always false and does not come into play. It is also considered MAIN because its conditions set the DV to closed most of the time and open under certain conditions, the opposite of B_ldsuas.
On a 1.8t or 2.7t, if you are removing your n249('s) and pneumatic DV and replacing it with an eDV from a TFSI, it will not operate as it should! The eDV will not open and close at the exact times that the pneumatic DV does. This is a problem as every time you shift and the throttle plate slaps closed due to deceleration, the DV needs to relieve back pressure from the turbo. If it does not, the turbo will "surge."
B_ldsuad's threshold needs to be lowered in order for operation to mimic what the pneumatic DV does; opens under every shift.
After some experimentation (and attempted calculation which didn't really go as well as I'd hoped) I found that lowering the entire table from mostly 200 hpa to 50 hpa accross the board did the trick for the most part. As you can see from the 2nd log PNG, B_ldsuad is set to true for every shift excluding 1. I'm still messing around with it to actuate for EVERY shift completely.
B_ldsuad is actuated if ALL of it's conditions are set true. In short, pedal gradient needs to be less than GWPLDU (in deceleration, negative value) and a boost error equation is greater than KFSDLDSUA. The third condition is always true. As a general rule, GWPLDU sets the sensitivity of B_ldsuad upon deceleration. KFSDLDSUA determines when B_ldsuad is set to true. This needs to be the focus for proper DV operation (if B_ldsuas is not to be used as the primary function)
I believe that you can tune SVDLDUVS, HSLDSUA, HSSLDSUA and LDUVRS together to utilize B_ldsuas in tandem with B_ldsuad so it actuates only under consistent cruise conditions and B_ldsuad operates for the majority of around town driving. I think this way, superior gas mileage can be achieved without sacrifice to part throttle power (via allowing the turbo to build boost).
The PDF attached has been pivotal to understand how the n249 (and subsequently, the DV if an eDV is used) is controlled. My synopsis is that the n249's purpose is to support DV opening function under certain conditions and not all conditions, thus for adaptation to an eDV parameters need to be modified.
B_ldsuad measuring: B_ldsuad (B_ldsua subsequently) missing shifts
B_ldsuad measuring-6: B_ldsuad (B_ldsua subsequently) operating for all (99%) of shifts
Once again, if all of this is common knowledge and I'm just spouting redundancies, please, let me know and I apologize.
Hopefully this will help someone out who is attempting this mod.