I think he's talking about a crank relearn. I think there's a lot of confusion over this procedure which is said to apply to 11+ Mustangs. My understanding is it's a Coyote thing. I can tell you I've had my transmission out of the car twice and my engine apart the same number of times, and I've never done, nor had to do, a crank relearn. Unless you see a P0315 code, I wouldn't go attempting it.