Mini Cooper diesel new maf issues?

[benlg81]

Hi

I have had a constant flat spot on the diesel cooper so far I have replaced

Thermostat and temp sensor
Air filter
Turbo seal
Charge pipe
Dpf delete + remap
Today -maf

Right with the old maf unplugged the car drives lovely no flats spots no smoke just a joy to drive

With the new and the old maf connected there is a flat spot mainly in second gear along with a lot of black smoke

I have re checked everything is air tight and also unplugged battery for 30 mins and then went into the secret menu on the software to do a ecu reset

I have only driven 10 miles but still got the second gear flat spot


Any ideas on what might be the issue

Any ideas ow long the mini ecu takes to re learn and stop over fuelling ?

[ch427]

could you expand on what you mean by having the old and new maf connected?
Was the new maf a genuine bmw part?