The cause of pinking ie timing, but just incase the noise is wrongly diagnosed, ie could be detonation, so to cover yourself, check timing
air fuel ratio,(to lean) spark plugs wrong grade etc, to much boost
fuel pressure etc, just check the basic setup ignition timing 12deg, btdc.
at idle speed approx 850-+50 rpm. souds like it just needs a check up.

DAVE R.