See that black box to the right of the dipstick in post #6? That is an electrically actuated valve assembly that regulates airflow in the two halves of the intake manifold. If you look closely on top of the intake manifold about midway down the box, you will see a sort of raised area where the valve is located inside the manifold. When it is broken, the symptoms are of a vacuum leak. The car will idle rough, but run ok at speed. You will also notice it not accelerating as well on pushing the pedal to the floorboard. How do I know all this? I just had mine replaced because I had a rough idle and a SES light. Lots of codes about intake, misfire, etc. It now purrs like a kitten again.
Maybe your problem? Just an idea.
Also note that when this part fails, there is a pin that holds the valve itself in place that comes loose. If that pin were to fall out and get in the intake of a cylinder, its bye bye engine.
I got lucky and mine didnt fall out. Whew.
Oh this was in my E46 2004 330Ci BTW.
2011 328i Convertible
: Mineral White; Oyster/Black Dakota Leather; Premium, Sport, Value; Sport Wheel w/paddles; Heated Front Seats; Satellite radio; HK Sound
2012 528i Sedan
: Titanium Silver; Oyster/Black Dakota Leather; Anthracite Wood; Comfort Access; Side & Top View Cameras; Cold Weather, Premium; Technology;
: Titanium Silver; Gray Leather; Premium, Sport; Fold Down Rear Seats; Xenon Headlights; Navigation System; HK Sound
2001 X5, 2009 528i
Last edited by bmwrocks; 12-05-2012 at 11:26 AM.