...please read in it's detail >> i know i as talking about my 2007 grand prix 3.8L n/a. but your info should still help. notice begiining of oct COOL day when i loaded 4 winter tires 215/60/16 with 4 steel rims and aired up . 1 on each side of rear seat and 1 each bascially side by side in the trunk.
i had to drive around a bit that day before and after load , so car was warmed up alot . everytime i stepped on the gas from a stand still or MANY times when i drove slow but had to step on the gas to pass etc. i would hear very load but breif pinging. i never paid any attention to rpms ( sorry )as to when it happened. after this i added a measured amount of fuel injectors cleaner to gas tank hoping that would fix .
now at end of month bit cooler some frosty nights , this trip was at night and car was cold ,i had me and on passenger front seat and 5 in back seat plastic storage tubs , each filled with clothes . i would GUESS maybe 25 to 35 pounds each ??? and in trunk this time again guessing 50 to 70 pounds ?? i could hear on hard excellaration at various times and volumes the pinging still. not has often or as load as before with the rim/tire load.
i use regular gas most often ESSO , car has 46,500 klms bought this may with 31,500 .
these 2 loads times fresh ( less then 3000 klms on it ) regular oil ,not cheapy but not most expensive either , this time quaker state this time i believe ?? all other fluids are good.
now this has a load carry rate ( occupants and load of of 917 pounds / 416kg ). ..i was way under that with the tub load + just me + trunk load Total 475 lbs ???
and i am sure i was not even close to that with the tire/rim total guessing 635 lbs ?? . basically load no load no ping .
with me + wife + 2 kids and normal trunk load 50 to 85 lbs, about 570 pounds , day old oil , long hwy trip etc ,again no ping