just this past saturday, my check engine light starts flashing when i'm cruising at 60 at 1.5k rpm. so i pull over check nothing under the hood loose from cables to the headers and spark plugs. two my amazement when i had it towed to my local mechanic, who 6 months earlier did a full 150k tune up says that my cylinder 8 has metal scraps metaled all over the piston and the plug is oily, while my cylinder 3 is starting to go now too. I'm thinking in my head what is going on here. I don't drive my truck like its a 10 second car, and i'm wondering what went wrong. I know guys i use motorcraft spark plugs cause i ain't an idiot to use 3 party brands from autozone or advance auto parts...

 

So did the mechanic use a borescope or something to see the pistons? And why was he looking this deep into the engine for a misfire? Is the metal aluminum? Are the threads in the spark plug bore damaged?

 

as for the details on what screen captures he got for me to see, they were just melted and tiny pieces like your finger nail tips. the spark plugs were in tact, just #8 had oily goo on it which he had replaced, and #3 was spotless, but showing signs of weak compression. I'm assuming from what other people have gone through with p0308, this could have been blown parts of a valve that are causing the lost in compression. hopefully i can get it a friend who owns a shop, if not get a second helping hand and get the job done in a whole day of inspecting and installing all the new parts. will post pics when i take the heads, cause if it ain't the valve that cracks i'm assuming its the heads that are going...

 

you could put a vacuum guage on it to see if it flutters (indicating a leaky int. valve). You can also use the hose from a compression guage, with shrader valve removed, to pressurize cylinder. At TDC on compession you'll be able to hear your compression loss. I always try to determine what happened before tearing things apart.