A common issue with direct fuel injection systems is carbon build up in the intake passages and intake valves. This buildup can cause rough running, lack of power and the check engine light to come on.
To correct this problem, the intake manifold needs to be removed and then an adaptor is attached to each intake port through which a walnut shell media is blasted and at the same time is vacuumed out.
The pictures show the work performed on a BMW Z4 with a six cylinder twin turbo engine.
The pictures show the engine with the intake manifold removed, walnut shell media blasted into the intake and then a comparison from before and after the procedure.
This process brings the intake system to a like new condition as seen on the pictures.