I was trying to troubleshoot a problem with my 5-series BMW when I stumbled across a thread on BimmerForums discussing the possibility that oiled air filters (like K&N) may possibly coat the Mass Air Flow sensor resulting in poor performance. My question is...has anyone ever heard this before? On my 540i, the MAF sensor is directly behind the air filter, so I can see how this may be true. How far upstream is the MAF on the Maser's 4.2L engine? Thoughts?