95 454 Catalytic converter burn out

[arejones]

Hi all,
I have a California smogged burb with 454, 4wd. Nox emmissions are high. Techs say engine combustion is too hot causing pre ignition and incomplete combustion. I don't hear pre-ignition pinging. But the emmissions are four times higher than average for the same vehicle. Anyone run into 454's burning out cat converters? Thanks.

Richard

[xjoeharperx]

Sounds like a too lean fuel mixture, but also what kind of gas are you using..if the octane is way too low it can cause pre-ignition. A mixture that is too rich can cause the same problem..But if you have oil vapor going into the cat and burning you will see all kinds of emissions problems.. includidng burnout and clogging..