I have a 08 mini s turbo has a cat less manifold changed 02 sensors then took for a long drive the next day was running it pretty hard then started misfiring got it limped home. Next day found a super nasty plug changed out all the plugs and it got a little better so I changed coil will start fine then will start missing them set p0300 and p0303. I changed 02 sensors to brand name ones and still hasn’t helped. Do you guys have any suggestions? High pressure fuel pump? It does smells really rich.

 

When I had my R55s I had to chase misfires for a month. New coils and plugs didn’t do it, had hpfp on hand, ended up needing to walnut blast the intake valves. Once they were done, misfires gone.

 

What codes do you recover using a tool that reads BMW/MINI fault codes?

Did you replace the upstream O2 sensor? If so, that's also something to check.

 

I changed upper and lower o2 sensors and plugs