[V8] Clogged Cats? - '90 V8q

[Buchholz, Steven]

... sure can!  My ur-Audi (the '78 Audi Fox GTI which Tom Nas is now restoring) exhibited this on more than one occurrence ... the car would start and run well when cold, and then gradually lose power as the engine warmed up.  The funny thing was that when things got really plugged up you could hear the pressurized exhaust hissing from whatever orifices it could find!  Test pipe proved it was the cat.  I assumed that the holes in the honeycomb were getting clogged up with something, but could never see inside when the cat was plugged ... 

My V8 BTDT is that via some mechanism the active material in the cat disintegrates ... there was no sign of anything inside the cans ... 

Steve B
San José, CA (USA)
> 
> I'm no expert, but I don't think a clogged cat would get more clogged
> when heated. Yes, there is some expansion of the material, but the
> degradation of the honey-comb is (or should be) what is causing the
> assumed clog.