R56 Cooper S, running on three!! Ideas Please

[atmotofoto1]

Hi Hi,

I bought my R56 Cooper S almost a year ago. It went to my local service garage, who went through everything, including a good service.

Very soon after it's MOT earlier this month, (Jan, and went through with no advisories), it's started running on three cylinders at low revs. At 2500, it runs on four and pulls strongly, all the way up to .. .. .. !!!

I replaced the plugs. And plugged in my OBD, Foxwell NT301, which shows no faults.

On checking some forums, there's seven possibles, all the way from a blocked breather hose, to a broken valve!! Hopefully, not a valve, as my thoughts are that the misfire would persist throughout the rev range.

Any thoughts, ideas, will be much appreciated!!

[ian_c_uk]

My first thought with those symptoms is the dreaded \ common high pressure fuel pump, as it sounds very similar (and no fault codes) to when I experienced it on my N18 Cooper S.

https://www.lohen.co.uk/mini-gen-2-mini-n14-n18-hi...

<other vendors available, just posting as it lists symptoms etc>

[E-bmw]

Equally likely to be in need of a decoke, these are very common issues on these engines.