well, fueling issues, with system too rich error, was this:- Block 032 long term would show > -20% to 25% to trip the MIL light where its trying to wind back fueling caused by the fuel pressure regulator not being able to regulate cos its filter screen is clogged with shyte.. the debris on there is rotten, degraded rubber hose! Fuel hose! like A4's reportedly suffer from also.. Seen this once before hence checking it sooner rather than later. concidentally, also a 225 S3 which I first came across this problem. the only rubber pipe upstream is the small link piece in the engine bay to the fuel rail. the rest is plastic pipe from the tank. why oh why do vag choose such poor grade rubbers on their engines?!?!?! If its a running problem, 8/10 times its a rubber pipe related issue.. doh! Cleaned.. and fueling was ok... BUT, not for long.. 4 dyno runs later.. I notice block 001 lambda adjust is back -20% level.. FFS.. Remove it again, clogged again! FIX: replace the link pipe to the rail complete with new piece. thoroughly clean rail off car, see the rest of the debris fall out in stringy like strands. ewww..