No, it is not normal to hear pinging. Is it rapid engine pinging when you accelerate? or do you mean something else (like metal expansion and contraction sounds)?If engine pinging:
1. You may have some bad gas in there. Might be worth trying some ISOHEET to remove water (that is a SWAG) ... make sure it is ISOHEET, not plain HEET.
2. Or carbon build-up. Some WOT's may clear it out, or you may need to use a can of BG-44K in the fuel tank and see if that helps.
3. If that does not help, then a power injector rail flush may work
These are guesses ... good luck and let us know if you figure out what it is.
Z
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