Melted Cats - What do I need to know?

[draculr]

My VEII SS developed a nasty rattle on cold start. Upon taking it in to the tuners who had fitted the exhaust they diagnosed it as a melted right side cat.

We're arranging to have the cats replaced.

They're going to put the car back on the dyno once the new cats are fitted and try to figure out why it happened which may involve additional repairs.

I really do trust these guys but I'm wondering if anyone else has had experience with this?

My questions would be along the lines of:

Is this going to be something that will keep popping up with this exhaust system?
Is it a sign that something else is majorly wrong with the car?
Can these tunes go bad over time causing such issues?
Is there anything that can be done on my part to prevent this from happening?

Edit: I should note that the car backfires a fair bit when changing gears (which is really fun let's be honest). It also really stinks up the place if left to idle for a while. Is that a case of the car running too rich and excess fuel igniting in the cats causing them to melt over time?

[Micks]

There's plenty to read about faulty cats, do a quick search mate! What brand? How many K's?

[BLACKVE]

sounds like it could be tune related, shouldn't be stinking up the place

[whitels1ss]

Damaged ceramic cats will rattle & can stink the place out simply because they are not working.

We don't know the full story, we don't know if it has factory ceramic cats or what sort of aftermarket cats,
the car could be lowered, the cats could have been scraping & getting broken up by having the shit knocked out of them by speed humps etc.

[IJ.]

Popping on overrun suggests DFCO is disabled....

Good chance that's what killed the CATS if it isn't impact damage.

[draculr]

Hey guys,

I've got the following on my car:

http://www.hmheaders.com.au/shopexd.asp?id=149

They're metalic cats. The car isn't lowered but one time I did bottom out (at the peak of an incline in a car park). The car popped and was running rich from day 1 of the tune.

I've seen a lot of threads suggest that popping on overrun isn't dangerous. Is it something that I should suggest gets reduced when they get it back for another tune? I had actually asked them to try to keep some of the pop when my initial tune was set up.

[Thunder]

If it is backfiring, that is unburnt fuel exploding inside the exhaust, and a problem with the tune.
Some cats are better than others, but they are not indestructible, so if you don't fix the tune problem you will probably go through more cats.