Just registered to this forum and read this thread on com2255's question.
What I would like to find out is: did indeed the purge valve fixed those problems, like P0455 and the very diffucult starting after re-fueling?
I have an 98 A6 with identical symptoms (85K miles).
Just got the car back from the shop. They replaced the MAF and Carbon canister, plus a load of other non related parts, to clear the P1136 & P1138 codes (sofar seems to be fixed?). But last night I fueled up the car and the starting problem has remained. Plus when I got home I checked the codes with my VAG-Com to note that P0455 was back.
I already replaced the gas cap a few weeks ago. The CEL is not on (yet), but I'm sure it will be in the next few days, after the EVAP has failed twice. BTW is there a way to initiate the EVAP test (code 071) on the VAG-Com, so I can try to diagnose (or listen hopefully) the leak during the test. When going to "Basic settings" it will sometimes 'open' the reed valve and turn test "ON" but then nothing happens futher with the testing. Or is this test only performed during driving conditions? I also own the Benthley CD, but there it is suggested to test the system under a slight N2 pressure. Any other suggestions?

I realize this is a long drawn question, but then again I've been looking for a fix since months on different forums. )-;
Any help is much appreciated.
FixA6