3219 - boss 302 engine rattle or rapping type sound.
some 2012 boss 302 mustangs might exhibit a rattle or rapping type sound during cold engine temperature operation at light loads and speeds from 1000 - 3500 rpm. This sound is caused by the piston moving from one side of the bore to the other at tdc. This is an inherent characteristic of the forged aluminum pistons and the combustion dynamics caused by the high flow cnc intake ports. Once the engine reaches operating temperature the sound will no longer be audible. There are no durability concerns with this sound.