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Holley Performance 550-604 HP EFI ECU And Harness Kit

4785403 - 550-604

Universal V8 Multi-Point Fuel Injection - Incl. ECU/Harness - Incl. Bosch Oxygen Sensor

550-604 HP EFI ECU And Harness Kit Holley Performance

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Holley Performance - HP EFI ECU And Harness Kit - Part#: 550-604 Features:

  • Simple Installation - Plug And Play
  • Self-Tuning Fuel Table Strategy Greatly Simplifies Tuning Process
  • 5.7 in. Color Touchscreen For On-The-Fly Tune/DataLog/Gauge Panel
  • Advance Idle/Closed Loop/Enrichment Strategy For Stable Operation
  • ECU Fully Potted/Can Mount In The Engine Compartment Or Interior
  • Individual Cylinder Fuel/Spark Control To Unlock Engine Potential
  • Can Be Configured Wet Or Dry With Closed Loop Feedback
  • Full Timing Retard/Contr

View the Full List of Automotive Applications »

Below is an abbreviated list of applications for the HP EFI ECU And Harness Kit.


Holley has been the undisputed leader in fuel systems for over 100 years. Holley carburetors have powered every NASCAR Sprint Cup team and nearly every NHRA Pro–Stock champion for four decades. Now, Holley EFI is dominating the performance world as well as our products for GM's LS engine. Holley's products also include performance fuel pumps, intake manifolds & engine dress–up products for street performance, race and marine applications. As a single solution, or partnered with products from other Holley companies - Hooker Headers, Flowtech Exhaust, NOS Nitrous, Weiand, Earl's Performance Plumbing, or Diablosport - Holley products can give you the edge you need over the competition.

Shipping Information

  • Item Requires Shipping
  • 9.0 lbs.
  • W11.0000” x H7.5000” x L12.2500”

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