Hi! Hoping someone can help with this because I’ve exhausted my (limited) mechanical know how. My partners R56 Cooper 1.6 (n12b16?) has developed an unusual surging/juddering on acceleration. It has 277D stored but that could be unrelated. It happens on almost every journey and is most noticeable when flooring it with the revs low to mid range. Less noticeable at high revs. It feels like for a brief second or two someone is stamping on and off the gas pedal. I’ve changed the oil (which weirdly seemed to improve things for a day or two but that could be my imagination) and cleaned the vanos actuators (exhaust side is fairly new anyway). I’ve also cleaned and swapped round every spark plug and swapped round all the coils. Every plug for every sensor I could reach has had its contacts cleaned. Still no improvement... what are your thoughts? Has anyone experienced anything very similar? If I were a betting man, I’d lean towards: clutch, oxygen sensor or cat on its way out. We have noticed that on start up when it’s been garaged, it leaves a little spatter of black soot on the wall behind the exhaust.