I've been trying to track down why my car (2.8) pings some times and not others...I've adjusting the timing,tried higher octane gas but it still pings....what I've noticed is that it doesn't do it cold and not when the cars warmed up...seems to start as soon as the car goes into closed loop and will ping until the car reaches temp....
egr is good....thing is I'm not 100% sure it is pinging but it sure sounds like it....it's odd that it seems related to operating temp...I first thought maybe a water pump or alt bearing but you can count on it not being there cold and going away when the engine is hot...and only under load at about 3000 rpm no sign of it when I rev the engine out of gear.
My motorhome generator has a small exhaust leak (new part on back order). Its noisy cold with no load. It goes away when its hot, but occasionally still leaks depending on the load on it. Goes away when I take off the load. Not saying thats it in your case, but possible. Id check carefully to see. If its really pinging, the timeing or gas octane would stop it, and it would usually only do it under acceleration under high load like pulling up a hill in too high a gear.
