I’ve asked this every year but I’ll try again in case anyone has thought of anything.

I have no engine lights on. Last year I change the cats even.

Anyway whenever I load the car up over 4000rpm the cats start to stink a bit like sulphur, it really does stink but runs fine and there are no codes etc logged… any ideas? Current stable:
2006 BMW M6
2007 4.2 V8 S/C FF
Gone:
2002 4.4 V8 FF

I had the same sulfury stink on my 2012TDV8, had no clue...
then I checked my collant level and it was very low
I so happened that i had a leaking gasket at the oil filter cooler (the classic failure on the V and my engine oil was sucking coolant...
It has to be changed.
1300€ later I'm all good.

I love that car

Cheers
Sylvain "it needs some intelligence to undestand you may not have enough"