Injecting air from an EGR makes the cats burn hotter - like blowing on hot embers - stoking the fire makes things burn hotter. After the engine reaches operating temp. - the cats go to work. I think light-off for cats is around 550-degrees. Late model converters flow very well because of the honeycomb internals. OEM converters are built much more HD than aftermarket ones - never chuck the OEM converters. they are built to last 8 years / 100,000 miles. Aftermarket cats are built to last 2 years/24,000.Originally posted by DL:
If you add the cats, do you have to run the air pump too? I think I heard something along the lines that you need the extra air to get the catalytic process to start.