Here's what the Ford engineer told me today:
"The 4.6L's have switched the piston to a smaller, lighter, higher performance shorter skirt piston that is designed to perfectly fit a warm engine. There may be noise when the engine is cold for the first few minutes. This is normal, hence, there is no fix for cold engine knock planned or in place. The noise you hear causes absolutely no wear and tear."
Here's what I said...
"Yeah, but the noise I get is LOUD...like the engine is coming apart, I can't believe there's no wear, and is there from 2,700-4,000 until the temp guage is mid. arc, which usually takes at least 15 minutes of warm-up.
90% of my driving is 20 minutes hops at the beginning and end of 12 hour shifts, so 90% of the time I'm either short-shifting or letting the car warm up 15 minutes for a 20 minute drive."
"It could be that your car has the noise louder than most. We'll have to meet when your engine's warm so I can hear it in person."
Seems we keep going around in circles. I had left my car overnight at Ford in October so the mechanic and foreman-supervisor could hear the knock. Now we're back to this again. I'll keep you all posted.