what would happen if you were to use your egr valve to supply
 

fresh air to the engine instead of exhaust? Just curious.

The engine would run lean and try increasing timing when it sees that the EGR is open then sense knock and reduce timing and/or close the EGR. It would be like having a vacuum leak in the engine and it would not be able to measure the total air coming in accurately, also the O2 sensor should see the extra air and add fuel to compensate.