Wiring & Plugs

Holley EFI LS main harnesses have a MAP sensor connecter designed for use with an LS1/2 style MAP sensor. The 558-416 is an adapter harness that can be used to adapt any LS harness that uses an LS1/2 MAP sensor connection to an LS3 MAP. Also great for...

Main Harness for 99-04 2 & 4 Valve Ford Modular (4.6 & 5.4L) Engines for use with Holley Smart Coils

An Injector Harness is required and Holley offers two. The harness with USCAR/Stock injector connectors will cover most applications that are using the factory injectors. The other harness is for the Bosch and Holley (or Jetronic/Minitimer) injector...

This Universal 4 Cylinder EV14 Injector Harness is designed to be plug and play with HP EFI & Dominator EFI Systems, utilizing our 205 LB/HR Injector Set - Part Number 522-205.

"Big Wire" Sub Harness- pre wired with 12ga power and grounds, for optimal performance!

Gen III HEMI Harness with TPS and Idle Air Control Connections.This wiring harness interfaces a Holley EFI ECU to a Gen III HEMI engine with an aftermarket cable actuated throttle body. It is meant to be used in conjunction with an injector harness, a...

Introducing 2x4 Terminator Stealth EFI upgrade components. The wait is over. These upgrade components allow you to use your current Terminator Stealth EFI throttle body, install a new main harness, and slave throttle body, and you are finished. This...

Introducing Coyote Twin Independent Variable Cam Timing Control from Holley EFI! Do you have a coyote crate engine going in your dream car? Is your weekend road race warrior powered by a coyote junkyard engine with locked cams? Unlock the full potential...

Drive-By-Wire harness for 2011-2017 Ford Coyote (5.0L) engines

Introducing the latest addition to the Holley EFI Product Lineup! Our EV6 unterminated injector harness is perfect for anyone wanting to add EV6 injectors to their engine bay.This harness kit comes with everything you need to build a custom cut to fit...

This is only used on applications using a CD Box, such as an MSD 6AL, while not using timing control.

Can Extension Harness (for Racepak and other external CAN drives)