P&G and cat temperature cycling?
 

I was logging some data this morning, and saw that in many P&G cycles, my catalytic converter temperature goes from ~500 degrees C to ~850 C and back. Even in more typical ones, there's still a ~250 degree C spread. Could all this heat cycling cause early failure?

Could the spread be much larger today because of wet weather, and on a dry day with no splashed water cooling the cat it wouldn't vary as much?

I'm not too concerned on my VW because it will be covered under warranty long after I return the car from its lease, but it may be bad for my truck and it may mean more to others here...

I've only heard of damaging a cat through rich/oil burn (clog), melt (lean), or mechanical (hit it) damage. it's meant to take sub-zero to 900+ degree temperature cycling day in day out, I doubt 500-850 (which is 350 difference btw, not to be nit-pickey or anything :-p) is gonna bother it.

My concern was the quantity of heat cycles. In general usage, it heats up and fluctuates much less during use than with P&G.

The 250 number was for "more typical" P&G cycles than the ones that resulted in the 350 difference.

There's really only one way to be sure.

"I say we take off and nuke the entire site from orbit." -Ellen Ripley

My point was that 900*+ sweeps do no appreciable damage over 20 years in a healthy engine. zero times fifty is still zero

Well, I'll let you know in 40,000 miles when I turn in my lease. :)