: Catalyst melted. Why?



Andrew M. Franklin
06-14-05, 09:21 AM
What would cause the catalyst element to melt on my '94 N*? It was rattling and I tried securing it with sheet metal screws, but soon discovered that it was in pieces about the size of golfballs. All busted up. I noticed that some of the pieces are melted, too. This thing must have gotten REALLY hot (2000 degrees?) What should I check to make sure my new one doesn't go bad, too? No engine codes other than persistant EGR pintle out of range. Car runs good. Thanks. Sincerely, Andy.

Ranger
06-14-05, 10:35 AM
I think a rich condition will lead to a hot cat. See if someone agrees.

turbojimmy
06-14-05, 10:53 AM
Yes, a rich condition. Raw fuel ignites inside it and it gets REALLY hot. I had 'em glowing red hot on my Mustang when a plug wire went bad.

Jim

mcowden
06-14-05, 03:49 PM
Agreed 100% with Ranger. If it runs rich, extra unburned fuel gets through to the cat, which is hot enough to ignite it. The extra fuel getting burned up in the cat is burning up the element and causing the problems you describe. If your oxygen sensors are bad or some other emission-related system has not been functioning properly for a while, or if you have a leaky FPR or injector, that could cause it. Or as turbojimmy mentioned, a non-firing cylinder will dump fuel into the exhaust and do it as well. Whatever causes it to run rich will cause the problem you describe. Do you have any stored DTCs or a Service Engine light?

greggbruce
06-15-05, 08:31 PM
if your egr pintle position is out of whack, it can make the computer think the engine is too lean, thus adding fuel, thus overheating your cat......

get that egr fixed.