2007 Ford Expedition Engine popping loud, please help?

[1955moose]

Besides messing up delicate cats on these vehicles. Breaking up carbon can be a risky proposition. General motors used to make a great additive that you poured down a carburetor when running. It would smoke like hell, but burned off carbon like nothing I'd ever seen. Problem is sometimes hunks of carbon would lodge in valve. I used to do oil change right afterward. In the old days a yellow porcelain was lead fouling from gasoline. Only 1 cylinder plug turning yellow/orange indicates a fuel mixture issue, along with carbon transfer to plug. You say your Suv runs/ idles as it should, but I read you had a dtc code, actually a few. What are you comparing running condition to. I'm going to throw out there along with the codes for cat, and weird spark plug reading, I'm thinking valve, or worn cam lobe/ rocker arm. If your getting the popping, that can be indicative of a valve not opening or sealing proper. When all else is tried you might want to pull valve covers, check cams, rockers, and do an old fashioned 8 cylinder compression test.

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[rjdelp7]

While agree that excessive carbon can foul up a cat...Seafoam is 100% petroleum based. I have used it for years on everything from the 3V 5.4 in my 05 expedition to my 2 cycle leaf blower. If you follow the directions it really works wonders.

Seafoam is 40% Naptha, 40% straw yellow/pale oil 10-20% Isopropyl. Soapy water in small amounts will decarbonize a engine. My Fathers favorite way, when were kids, was to go on the highway and 'blow it out'. The old cars, you actually see black soot, come out of the tailpipe.

 

[Boose]

I tried desperately to find an MSDS on the stuff