Wiring Harness for 4.6 with EFI - Factory Five Racing Jan 08, 2017MK4 Complete kit. Has anyone used a 4.6 DOHC with EFI? What did you do for the EFI wiring harness? FFR does not carry one. Did you use the donor car's complete wiring or marry the undere hood wiring to the kit harness? THX Ford 4.6/5.4 EFI wiring harness kit Telorvek design | Wire Dec 13, 2017This harness is for the engine and transmission wiring for a Ford 4. It will allow you to wire the engine and transmission when installing them into a earlier model vehicle like Cobra kit cars, Muscle cars, Street rods, Trucks and 4×4, etc. This is not a factory replacement wiring harness.