I had same problem, and I know its an old post, but I had the same problem. Maybe this helps some one but changing and properly gapping the plugs stop all the pinging for me.

 

Our pinging sound: We had a pinging in our 01 Ex V10. Bought it used and it wasn't doing that until a couple weeks later. We added an additive to the vehicle hoping it would quiet it down, but no change in sound. We figured we'd drive it until it blew up because we couldn't afford a new engine. Instead of blowing the engine we blew a spark plug which we are working on today -- our Cal Van kit arrived yesterday to fix the threads!

 

Welcome to the EX forum!

Ping or tapping preceded the blown plug? Many folks report hearing a tapping shortly before ejecting a plug, the noise is escaping cylinder pressure around the loose plug threads.
Along with your upcoming thread repair to that hole will you also be changing out all of the plugs, boots and springs? It's not very expensive or all that difficult to do and can improve the economy and performance if the current plugs/boots are high mileage.
What torque setting are you going to be using with the new plug(s)?

 

My Excursion has made this noise since I got it.

I don’t worry about it. Simply because so many people HERE say it’s a normal thing with the V-10’s

Got my 05 Ex with 90K miles on it and now I’m at 171K. Still making the noise but haven’t had any issues.

 

I have 3 excursions with V10s. From 240000 miles to 111000 miles. None of them ping. One is even supercharged. It can see 6 psi of boost while in closed loop at 2200 rpm and does not "ping".

The other 2 eat 85 octane fuel with no issues.....Note that is standard fuel at 7000 ft elevation.

If you have a V10 that is pinging something is not right. That' why the new OP posted his results. Which is really good info.