I hear it sometimes and it gets on my nerves. If i put 89 or 91 octane in it, i cant hear the pinging. I figured it would go away if i change the spark plugs and well i didnt know when the previous owner changed them so i did it anyways. They use to be Bosch plugs and 1 & 3 were all rusted 2 & 4 had a lot of carbon deposits on them. I couldnt find any NGK plugs around here and the local nissan dealer is kinda expensive so i decided to put in some denso plugs. It smoothed out my idle and the pinging went away but within a week and a half it came back. What do i do now? Should I change my plug wires as well??