[BAFOMET]

Long time lurker here, and I am stumped on an issue with our '11 328i.

The car had the SULEV fuel pump issue, and would not start. Had the car towed to the local (and useless) BMW dealer who replaced the failed fuel pump under limited parts warranty and returned the car to us. Within 2 miles of leaving the dealer (after hours of course) the SES illuminated. The car presented with two codes, 29F4 and 29F5. A long story cut very short... we brought the car back to the same dealer to leave only with confirmation of the codes, but no true diagnosis, and essentially a good luck and a pat on the backside as the car had the secondary cats removed by the previous owner. (Yes, I know that this is irrelevant, however, when the dealer is inept they are willing to point to whatever they can to get you out the door... BMW NA has been made aware.)

To my current confusion... I clear the code and the car runs significantly better. Idle is smoother, pulls stronger, throttle response is improved and overall the car sounds less rich and seems to run "right." Between 40 and 60 miles of driving later, the codes will return and the car begins to degrade in performance and response. The car did not present with these codes prior to the fuel pump failure, but was cranked considerably on the road side trying to get it off the road and in a safe place. Car has 125k miles currently.

I can't believe that the cats are bad if performance changes so drastically, but cant confirm. I also do not want to shotgun the problem and replace 4 AFR sensors or both cats without confirmation. Any comments or suggestions are appreciated!! Thanks in advance!