Problem with naturally carbing a keg...

I made up 10 gallons of Dunkelwiezen. The plan was to keg 5 and bottle 5. all went well and I had most of the bottles filled when SWMBO informed me that I was out of caps!! SO I had already added 4 oz. of priming sugar to the bottling bucket. I poured the remaining bottles back in the bucket, and dumped the bucket to a free keg. No harm I thought.

Now this is where I'm convinced all my bad batches have been ruined by my BAC while brewing.

I put it in the keggerator, gassed it up to about 15psi and let is sit for about two weeks, until last night I tried it, and it's horrible, the other keg though was great! SO I think I screwed up by chilling it, it probably should have sat out for a few weeks so the yeast could eat the sugar? Such a waste of beer about 3 gal too!!

Did you dump the bottles? Maybe oxidation. What flavors are you tasting?

If it is just sweet from the priming sugar, pull the keg out and let it warm back up for a week or two. The yeast should wake back up and get back to work.

Assuming it is not oxidation that you are tasting, that is.

No, not any sweeter than a dunkel already is. I was almost thinking it was oxidized by the flavour. it's also strongly noticed in the aroma. I don't know what oxidation smells/tastes like though?

From the Wiki:

Oxidation in Beer
Cardboard-like oxidation flavors and aromas are not considered appropriate in any style

This actually might be it, I really tried to pour the beer back slowly, but who knows? also with only 3 gal in a 5 gal keg, maybe I didn't get the head space purged fully?

If you didn't purge the space, and poured them pretty aggressively, it could be oxidization, but I can't see it creeping in that soon unless you were really careless.

I'd sit it out at room temp for 2-3weeks, and see what happens. Put it on the gas and pour out the first half glass atleast. See how it is then. Nothing to lose but the time that you invest in putting it in and out of the kegerator.

I didn't pour into the keg, rather into the bottling bucket, then racked the bucket to the keg . I'm sipping it now, and the flavour comes and goes, buy lingers on the tounge as a bit of a after taste. It is kind of cardboardy. Not that I'm a cardboard aficionado, LOL. But the correct beer flavour can be detected thrkough it, and what the hell I'm out of beer otherwise, I'll keep sipping.

You drink half the keg and bet you won't notice any off flavor or any flavor for that matter. ;-)

It definitely sounds like oxidation, unfortunately. If you can stomach it, drink it sooner rather than later as it will get worse.