[zataka]

My friends M135i 2013 with a N55 engine has all sorts of idle problems. Car may shut down on its own, has misfires and rough idle.

Help needed on what to do first, ventilation system on the valve cover is faulty i think,it has been DIY repaired by previous owner, spark plugs might need a change,ignition coils could be at fault too? how about vanos solenoids?

Also the car has a map on it but no idea how to tell what kind of map it has, how to identify it? Friend has xhp diagnostic tool if it helps. So many things that could have effect on the idle but no idea where to start.

[chassis]

Take the map off, change spark plugs and coils and report back.