"Jeff Strickland" > wrote in message
...
>
> "R. Mark Clayton" > wrote in message
> ...
>> Whilst you were not firing one cylinder lots of unburnt fuel will have
>> got into the cat and 'polluted' it.
>>
>> Now that all six are firing again, my guess is that a couple of long runs
>> will warm the cat up, provide exhaust with low levels of hydrocarbon and
>> allow catalytic conversion of hydrocarbons in the cat' restoring it to
>> health.
>>
>>
>
> You think I can "clean" the CAT? That's a comforting thought. I'm all
> about saving money, and the wait-and-see method of repair seems logical
> given the cost of repair.
>
>

That depends on whether the catalyst has been inhibited (by the condensation
of hydrocarbons) or poisoned.

See http://en.wikipedia.org/wiki/Catalysis

I think the latter unlikely BMW's web site boasts "The system uses a special
set of parameters in the engine's warming-up phase in order to help the
catalytic converter reach its ideal operating temperature more quickly,
lowering emissions..." for double Vanos engines.

A good run will also help in removing oil and / or deposits in the
mis-firing cylinder.