SKU: 5270546285

Holley HP EFI ECU and Harness Kits 550-604

Sale price$1237.47 Regular price$1374.97
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  • USA
  • CAN

Ships within 48 hours · Estimated delivery Aug 7 - Aug 12

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Description

Holley HP EFI ECU and Harness Kits 550-604MPFI HP ECU AND HARNESS KIT Looking for a plug and play alternative for your stock or built late model factory EFI engine? How about a replacement ECU for your older Holley C950? Holley has you covered. HP EFI ECU and harness kits are designed to be used with popular factory EFI engines as an alternative to the factory ECU and harness or as a replacement for your C950 ECU. The HP allows you to accurately control the fuel and ignition of your engine

MPFI HP ECU AND HARNESS KIT

Looking for a plug and play alternative for your stock or built late model factory EFI engine? How about a replacement ECU for your older Holley C950? Holley has you covered. HP EFI ECU and harness kits are designed to be used with popular factory EFI engines as an alternative to the factory ECU and harness or as a replacement for your C950 ECU. The HP allows you to accurately control the fuel and ignition of your engine along with additional controls for nitrous, boost or water meth.

Features:

  • Optional 5.7” full-color touchscreen LCD allows easy on-the-fly tuning, data-logging or can be used as an easy to see graphical gauge panel
  • Eight sequentially driven 8:2 peak and hold injector drivers, capable of driving up to 16 low or high impedance injectors as a standard feature. Multiple staged injector strategies
  • Eight channel Distributorless Ignition (DIS)outputs capable of directly driving “Smart” ignition coils or Holley DIS coils. Will drive 2 wire coils with the addition of PN 554-112 high current coil driver module
  • Integrated single channel wide band oxygen sensor control. Works with NTK or Bosch sensors
  • Internal data-logging standard with a huge 2GB of memory
  • 4 Stage progressive nitrous control
  • Turbo boost control
  • Integrated water/methanol injection control
  • Self-tuning fuel table strategy greatly simplifies tuning process
  • Individual cylinder fuel and spark control allows you to unlock your engine’s potential
  • Works with 4, 6, 8 cylinder engines
  • Unique lb/hr based fueling strategy greatly simplifies and commonizes tuning
  • Advanced idle, closed loop, and enrichment strategies allow for very stable operation
  • ECU is fully potted and can be mounted in the engine compartment or interior
  • Sealed automotive and marine grade connectors
  • Allows for use of common OEM sensors as well as customer sensor calibration input
  • Ignition Plug and Play with GM HEI, Ford TFI, magnetic and hall effect trigger, and other ignition systems. New Plug and Play applications in process. Custom settings can be configured to allow many other applications
  • 1-5 Bar MAP sensor capability
  • Two channel knock control sensor Inputs for both one or two wire knock sensors
  • Dedicated fuel and oil pressure inputs
  • Controls both stepper and PWM Idle Air Control (IAC) motors
  • Speed density, Alpha-N, or combination fueling strategies
  • 4 Programmable high or low Pulse Width Modulated (PWM) outputs and 4 fully configurable inputs can be configured for use
  • 4 Stage nitrous oxide control
  • Fully featured nitrous control eliminates the need for a separate nitrous controller device
  • Can be configured “Wet” or “Dry” with closed loop feedback
  • Progressive control based on time, RPM, or boost, requires part # 554-111
  • Lean or rich safety cutoff
  • Full timing retard/control configurability per stage based on RPM or time
  • Integrated Water/Methanol injection control
  • Uses Holley Water/Meth solenoids specially designed and calibrated for use with this EFI system to allow the user to enter Water/Meth flow as a percentage of fuel injector flow for Water/Meth tuning precision unmatched in the industry

Application

  • Universal

Specs

Brand Holley EFI
Emission Code 3
Ignition Type Coil - (No Timing Control)
Ford TFI
GM HEI Small Cap
Holley Dual Sync Distributor
Injector Connector Jetronic / Minitimer (Bosch)
Product Type HP EFI Kit
Part Number 550-604
Shipping Notes
  • Free Standard Shipping on $100+ Orders to the USA.
  • Except Preorder products are shipped in 48 hours.
  • Delivery to the USA:
  1. Standard Shipping : 3-10 business days
  • If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
  • We offer a 30-day return/exchange service after receiving.
  • Final sale items are not eligible for returns or exchanges.
  • To process your return/exchange, please contact us at [email protected]
  • Please click here for more details>>> Return & Exchange Policy
SKU: 5270546285

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LAX MOM
Omaha, US
★★★★★ 5
nice
Size: 24 Inch, Color: White, Number of Items: 1
Easy to install and stron enough to hold several work binders and books
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Reviewed in the United States on May 2, 2026
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Wendy
Draper, US
★★★★★ 5
Nice sturdy shelves
Size: 36 Inch, Color: White, Number of Items: 2
These nice deep floating shelves look perfect in our guest bedroom! Very sturdy and they are able to hold large items.
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Reviewed in the United States on December 20, 2025
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Pam Mitchell
Port Orchard, US
★★★★★ 1
Poor quality product, hardware not appropriate
Size: 24 Inch, Color: Black, Number of Items: 1, Size: 24 Inch, Color: Black, Number of Items: 1
Do not waste your money on these, not as described, very cheap, hardware does not work. Going to have to repair my wall before I can do anything else. Completely unacceptable product. Very frustrating and was not properly represented in the marketing advertising. Do not buy. Would like to return, but waited 3 days to long. If I had opened them immediately I would have seen the poor quality.
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Reviewed in the United States on May 2, 2026
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Jeffrey Balog
Birmingham, US
★★★★★ 5
All in one end table
Color: Cherry, Number of Items: 1
Very well made and solid. All the parts fit together perfectly. Very convenient you can plug in a lamp and charge your phone with the usb ports. Great value for the money.
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Reviewed in the United States on January 12, 2026
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Fit Instructor
Draper, US
★★★★★ 5
Perfect
Color: White, Number of Items: 2
These are the perfect size. A little long cumbersome putting them together. They look very nice for a small nightstand
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Reviewed in the United States on April 19, 2026

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