Lexus GX470, 2003. My passenger side coil #4 and spark plug blew, melted, broke to pieces. It was hard work getting it out but I succeeded. My threads to hold the spark plug were gone so I made new threads with Save a Thread. I did a lot of research and I bought a borescope camera to make sure my new threads were flush where spark plug sits and make sure no dubree was stuck in the piston, cylinder walls or valves. Air gun and some brakleen was used to clean and remove everything. Permatex red thread lock high temperature was used to install new threads and I gently tapped it. I let it curate for 24 hours. Then installed new spark plug and coil. I started the engine I got the same sound as I was before with a bad spark plug. I removed new coil and spark plug and inserted my borescope to check everything is good and everything looks and feels good. I installed everything back and still have the same noise. Tip of spark plug looks good no signs of piston hitting it. If I fixed it why do I have the same noise? Please advise. Thanks