[s-cars] S6 Mileage

[Steve Marinello]

I'm really puzzled by the mileage figures you guys are quoting.  Prior
to the still ongoing 'disaster' with the concurrent cat/exhaust
replacement (Magnaflow cats adn mufflers), then new O2 sensor and
newer tech injectors from 034, my S6 avant ran much better mileage
regularly.  The car came to me initially with and RS2 injectors, turbo
and exhaust manifold and an Abt rear muffler section. This was while
in Louisiana; car sourced from Chicagoland. Do not know the software
for sure, but believe it to be MTM.  The car regularly got 25-27 mpg
running from LA to TX.  On one trip from AL to LA, it got 28+ mpg, but
got 26 mpg on the way out.  The town mileage, however, was less than I
was hoping for, at 16-17 mpg.  I pulled the RS2 injectors and went
back to stock to see if city mileage would improve (since I wasn't
pushing the car), and it seemed to slightly, but the highway mileage
dropped a bit, such that I was seeing mostly 25 mpg, not 27.  Since
the messed up mods of three years ago, which I have never gotten
straightened out, it's more like 15 and 22, which doesn't sound too
far off the stated results.  And the car is running noticeably rich.
I'm getting the RS2 injectors rebuilt, if they say it is possible,
putting on another O2 sensor and going to a more quiet and
non-resonating exhaust (I hope) from Paul Fernandes.  My target is
something akin to what I had before, which seems a longshot after all
these data points.  I've been wondering if something screwed up the
ECU code, as well, or if the too-free-flowing exhaust just doesn't
help things.

But I really am surprised by the low numbers.  The original setup was
estimated to have been putting out about 340 hp, but I never had it
dynoed. Ran like stink.  Runs like shit now with slow climbing boost,
but no leaks apparent.  Oh...I did put on a Stratmosphere valve
somewhere in there. It seemed to be working, but I think it will be
replaced in the next round if things don't improve.  One other weird
point I may have mentioned before...034 sent me a mismatched set of
injectors and never responded with a replacement..4+1, although the
specs are virtually the same.

Anyway, I'm not sure I would have kept and kept dumping $$$ into, the
car if I had  seen only 21 mpg highway all the time I've had it...

Just my experience...

Steve