"direct and manifold injection so may not be as vulnerable to carbon build up on valve stems as earlier pure direct ones."
Yes this is quite possibly correct. However BMW techies say they still sometimes have to remove inlets on B58s and blast clean with ground walnut shells on high mileage examples or cars used mainly for short journeys. It is not an insignificant job.
When I removed the head of my 2014 Plus 4 GDI engine after 20 k Miles which had been on VTA (vent to atmosphere) from new the inlet tracts and inlet valves were almost like new. The GDTI (260 bhp Focus ST turbo engine) I replaced it with
has also beneffitted from VTA from new.
pip pip
