2.7t producing just under 12 v

[Mark R]

1998 2.7T?  That's an expensive route for S4 power!

Find what caused the smoking smell.  Likely, it's a short and presuming the
gauge is correct, the short may be enough to draw down the amperage
available to the gauge, therefore correctly indicating a voltage drop.

It goes without saying, this is a dangerous situation.  How much wiring was
touched when the engine conversion was done.  Also, low voltage has the
potential of damaging control modules

And why aren't you up playing at winter driving school in Dalton, NH with
North Atlantic Audi?   =)

Mark Rosenkrantz