This cake is so moist that it doesn't need a frosting or glaze.
Preheat oven to 350°.
Beat sugar and margarine at medium speed of a mixer until well-blended (about 5 minutes). Gradually add egg substitute, beating well. Add 2 1/2 cups sweet potatoes (about 1 1/2 cans); beat well. Reserve remaining sweet potatoes for another use.
Combine flour and next 5 ingredients (flour through salt); stir well. Gradually add flour mixture to sweet potato mixture, beating well after each addition. Stir in vanilla.
Pour batter into a 10-inch tube pan coated with cooking spray. Sprinkle coconut and pecans over batter. Bake at 350° for 1 hour and 25 minutes or until a wooden pick inserted in center comes out clean. Let cool in pan 10 minutes; remove from pan. Let cool completely on a wire rack.
Note: Substitute 6 egg whites (about 3/4 cup) for egg substitute, if desired.