Wonder if anyone can help me out on this ...
Lately, I've been experiencing engine pings ONLY under hard acceleration PAST 4,000 rpm. It doesn't happens below 4,000 rpm, whatever the load. Mechanic has checked ignition timing and its right on the dot. Tried retarding the ignition timing and the problem still persists. Checked CO as well and its within specs. Have not made any changes recently except for a change to a set of Bosch Platinum +4 plugs. Whats happening???