Preheat oven to 325F. Set racks in top and bottom third positions. Prep 3 9-inch cake pans by spraying liberally with nonstick baking spray.
In a large bowl, mix together, flour, baking powder, baking soda, and salt. Set aside.
In bowl of stand mixer, add oil, butter, sugar, and maple syrup and mix for 2 minutes on high speed until pale and fluffy. Add eggs one at a time and combine until well combined.
Reduce speed and add dry ingredients in two additions. Add sour cream, milk, vanilla and pecans and continue on low speed until just mixed. Do not overmix.
Bake until cakes start to pull away from the edges and are a very light brown on top, about 25 minutes. Rotate cakes from top to bottom racks halfway through baking.
Remove cakes from oven and cool in pans on wire rack for 10 minutes. Turn cakes out of pans and finish cooling on wire racks, about 25 minutes.