Recently bought a 1999 S80 2.4 which pinks (knocks) under light load. Plugs changed,engine temp normal (mid position on guage). I have changed the knock sensor,and checked the hot air flap below the air filter isn't sticking in the open position, doesn't appear to be sucking air. Fuel grade 97RON. Diagnostics indicate that there are no stored or pending codes. Air temp from MAF 10 degrees above outside air temp.

Problem doesn't occur during warmup from cold.

Would welcome any help or suggestions

 

I have seen a dirty throttle body cause this before.