One of the most intimidating aspects of this swap is wiring the fuel injection. We used a factory engine harness from the donor and got our hands on a factory service manual, then whittled down the harness to only what we needed to make the engine run. While tedious, it’s not particularly hard if you can read schematics and pay attention. The rat’s nest in the box is what we cut out of the donor harness. Though we retained the power distribution center from the donor harness, we used just three circuits and relays: the fuel pump relay, ASD relay, and starter solenoid relay. In the end, there are only three connections needed from the original harness to the EFI harness: constant power, starting power, and start/run power.