Mark, help me understand how this system works, on an FI ENGINE, as we have no PCV Valve. My understanding is that the "breather" we are discussing in the pic below is actually a misnomer for an FI engine, as there is no actual separate fresh air source intake for the crankcase. The system (that steve8462 plugged) on an FI engine, just allows built up pressure from blow-by to be vented back to the intake. As in the non FI engines, plugging it would allow pressure from blow-by to build up, with bad consequences.
And filling the crankcase too high with oil allows too much oil mist to enter the system and fouls the FI intake. I have seen this firsthand. I tend to use a little extra oil in my car (4-1\2 to 4-3\4 qts), as it seems to like it, but if I go up to 5 qts, a very small amount of oil slowly makes its way up to the intake Manifold and coats it with a slight film.
Have I got this right
