Preheat the oven to 325°F (160°C).
Microwave 2/3 cup of the chocolate chips and the butter in a bowl, stirring every 30 seconds or so, until melted, 60 to 90 seconds total.
Whisk in the oil and cocoa until smooth.
In a separate bowl, whisk the sugar, eggs, vanilla, and salt until smooth and thick.
Whisk the chocolate mixture into the sugar mixture just until incorporated.
Stir in the flour and remaining 1/3 cup of chocolate chips until just combined.
Scatter the pecans over the pie crust.
Pour the chocolate fudge batter over the top, using a spatula to smooth the top. Bake the pie until a toothpick inserted in the center comes out with a thin coating of batter attached, 30 to 35 minutes.
Let the pie cool on wire rack until barely warm, about 1 1/2 hours. Slice and serve. (The pie is best warm from the oven but it can be reheated, uncovered, in a 300°F (150°C) oven until warm throughout, 10 to 15 minutes.)