All of engine connections for the fuel injection come together at the relay box. Below it is the controller for the wide-band oxygen sensor. The small black cable with the large connector leads off to the ECU, located inside the car. The fuel injection wiring is contained in a secondary harness that parallels the original wiring. Wrapped with identical harness tape and with a Lucas decal, it looks right at home. The factory Malibu fuel system used a remote fuel pressure regulator that was part of the fuel plumbing on the car, not part of the engine assembly. The 3.5 engine also requires 50 psi fuel pressure, which led to the use of an adjustable, external regulator.