Join Date: May 2013
Location: Left Coast, Canada
CC's will have problems if any engine fluids (oil, fuel, antifreeze) get into the exhaust system. Fuel from a too rich mixture will ignite when it hits the CC creating higher heat which can melt it. Excessive oil and antifreeze in the blow-by will plug the CC creating more back pressure than designed thus giving you poor performance.
The rotten egg smell is from the sulphur in gas. The refining process gets most out but not all. What remains is burnt up in the converter. If there is a stink either the converter is just not up to it's proper operating temperature yet or it's damaged.
By the way, there are still some arguments about how much benefit the CC's actually provide to the environment. If you are interested check out some info. Also, some of those CC's sitting idle on cars that have reached the end of their life can actually be worth quite a bit at the scrap metal dealer.
Not all those who wander are lost.