ajg617

Can anyone explain the technical reasons why the CATS fail so frequently and more quickly on the 3.0L engine compared to the 2.8 or 2.7T? I know that the coding is very restrictive and a flash has been offered for both the 2.8 and 2.7T - not for the 3.0, but the 3.0 still seems to be the worst (this according to Audi and my indy from experience). Just curious.
Thanks,
AJG

ECS Tuning-Audi

Not exactly sure what you mean by "coding" but it may just be a manufacture defect.

Cats usually are the last to fail as it takes many many heat cycles to burn them out.

Or boosted engines the possibility of unburnt fuel to ignite in the cats is much more common than in NA motors. This can lead to premature failure or over heating as well.

Jason

ajg617

Referring to this thread.

https://www.audiworld.com/forums/sho....php?t=2776642

I've seen the TSB for the 2.7T, not the 2.8. I have a 3.0. Been through this with GM on disc brake rotors. Recalled every model except mine - not enough sold to warrant a recall or TSB. My front rotor separated at the hub to braking surface joint at the composite weld. Every other 1500 model before and after was affected.

Prospeeder

3.0 engines have the hideous red ignition coils that fail regularly, all it takes is a super hot cat, a missfire, and raw fuel hitting the cat to destroy it.

ajg617

Well, I did have some coil problems earlier. Had to replace two, one on each bank. Then Audi recalled the vehicle and replaced them all. But that was after the Cats were throwing codes and at over 120K.