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Blowing through cats every 8-10k mi?

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This happened to the previous owner twice. When I purchased the truck (right after the second engine blew) i replaced the engine. I inspected the catalytic converters and realized that they were hollowed out. I then put the cheapest cats money could buy on the truck. They blew out within a week and left me on the side of the road. I then paid up and got some good AP cats. Just recently I started getting my 420s & 430s again. I get a whistle that comes from the exhaust and i assume its just because there isn't a clear passageway. My pressure also builds up on high acceleration. Does anyone have an answer to why my truck burns through these things like nothing? cant be the engine because this is the 3rd engine that has blown them out.

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14 hours ago, CamGTP said:

Anything that isn't from GM or those high dollar Magnaflow cats just don't last.

Thats what I figured, but AP is a high dollar cat. I mean we are talking about $1500 for the part alone. Doesn’t make sense that it would just blow out after 4-5 months

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10 hours ago, richard wysong said:

Cats don't die on their own, they are murdered by the way the engine runs. 

Also something I had a general idea of, but I can’t comprehend how 3 different engines have all blown out cats. Am I being too hard on the truck? I mean for the most part I don’t even get over 3k rpm. It just doesn’t make sense 

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It is not the engine itself but the sensors that control the fuel mixture. Are you swapping complete engines or just long blocks and using the original manifolds, sensors and accessories? Sounds like you may be running too rich causing the substrate to melt down

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