Please do shine some light on this "pinging"

 

Sounds like someone shaking a can of marbles really fast, or like rapid fire popcorn popping coming from your engine. It happens when your timing is to far advanced for your fuel octane level, in the case of the tuner.

The old 3.9L V6, 5.2L V8, and 5.9L V8 had it far more commonly. They were infamous for blowing a "plenum gasket", technically called the lower intake manifold gasket, and allowing oil into the air plenum of the intake manifold. This oil would then get sucked into the cylinders with the air, and screw up the air/fuel ratio. Among other things, it resulted in pinging quite frequently.

In short, its predetonation in the cylinders, which means the air/fuel is exploding before it should. A little bit of this usually doesn't cause any issues, but it sounds terrible and means you aren't getting full detonation in the cylinder, robbing you of power and MPGs. Frequent pinging can mean damage to the cylinders.