Whenever I floor it and the rpm get around 4k, the car starts sputtering HARD and a lot. I had one of my friends drive behind me and he said it spits black smoke. The only things done to the car right now is an intake and catless downpipe but I've had them on for awhile and this just recently started happening. Any help would be very appreciated.

2013 Mini Cooper S

 

I've had the sputtering problem before, but for me it was because my spark plugs were done and was misfiring out of cylinder 2..

 

How many miles? Any codes?

 

This

 

None of my pistons are misfiring I checked.

 

45k miles and no codes that involve this issue. But I plugged an obd engine checker thing and when I looked at the two O2 sensors it said that O2 Sensor 1 was at 0.00v and O2 Sensor 2 was at 0.46v (this was with the car idling for about 5 minutes).