Pecan pie is finnicky. Sometimes when you cooking at the right temperature long enough to set the filling, the crust burns.
Fortunately, the fix is simple. It's called a pie crust shield.
Cut a square of aluminum foil around three or four inches wider than your pie. Fold it in half, and then in half again, so it is one-quarter the size of the original. About three or four inches from the point (the corner with folds, no edges), cut out a quarter-circle with scissors. Unfold. You should have a 6-8" circle in the center of your aluminum foil square. Place this over the pie and fold down around the edges. This will protect your crust while the pie bakes. Remove it for about the last fifteen minutes of baking.
From The Secret to Perfect Pecan Pie Updated on August 25, 2017