Okay guys I am stumped, I had a mishap with my truck and managed to grenade (literally) an injector. The dealership is covering the repair under warranty despite the presence of a programmer. The injector was replaced and tests run but now it seems that the when compressed air is blown into the cynlinder, the air comes back out of the oil pickup tube.

Now my questions are how could this happen? And since it has happened how bad is the damage? Any thoughts would be greatly appreciated.