with the plate removed it is thinking more air is flowing than what it was calibrated. It gives it a little more fuel than normal on load because on cruise the o2 sensor with lean it back out. The richer mixture wil reduse detonation. I would double check the EGR flow and I'm not sure without research but if that engine uses a knock sensor and if it does if it is working. Fuel pressure gauge while pinging is a big one