Originally Posted by peeti
Sorry to resurrect this topic - but in my wife's 335i a rich condition led to the cat exploding. Basically over time unburnt exhaust chunkies went downpipe and settled in the honeycomb. It ignited at some point and sent cat material down system.
Is it possible - open mind everyone - that the cold start warmup is warming up the cats to also prevent rich exhaust from going into the cat and reducing cat life?
Food for thought, thanks for sharing. Also to note, BMW has had problems with the HPFP on the n54s Perhaps pump failure was to blame for the overly rich mixture - altough there should have been signs of the car misfiring. Anyways 335s don't have cold start.
I once had my cat puggled by a rich mixture and my car stalled (this is not a BMW).
In any case, has anyone stood behind the exhaust on the dyno? Close to redline, it feels like the exhaust is venting 30mph winds. So in theory, a trip to redline once in a while is good for the car