I posted a few weeks ago that I was hearing a valve taping coming from my '95 525 at idle. It would come and go. Almost like once it got loud enough, the anti-knock system would kick-in and reduce it. Then it would start getting louder again. Anyway, the tapping is pretty much quieted down now (I can still hear it a little, and more so with the stethoscope of course). However, now I'm getting some valve pinging when driving the car. I've got 93 octane in it and I still get some minor pinging. Also when I pull in the garage, I notice a "rotton egg" smell. Like maybe the car is running rich. Can anyone put all of these clue's together? I'll probably take it to the dealer next week I guess.