SKU: 5270546285

Holley HP EFI ECU and Harness Kits 550-604

Sale price$1237.47 Regular price$1374.97
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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]
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SKU: 5270546285

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Melissa Williams
Belleville, US
★★★★★ 4
4.25 stars
Format: Kindle
Vale is an 8 month pregnant omega working as a waitress at a strip club and a cam girl. She starts to get very creepy vibes from a regular at the club, and her baby daddy ghosted her. She has had an online relationship with a man named Bishop through her cam girl status. One night, bishop was paying to watch her sleep and ansthe creepy regular Andrew break in and watch her sleep he tells vale to come to him at his business now. She flees and finds herself at a large security company with some.hot of alphas who are there to help her. This imegaverse is a little different than I have read, but I am thoroughly enjoying it. Vale is not a traditional omega she was raised by a single beta mom, and the alphas are not normal alphas they have never really loved pack life. But they are ruthless mercenaries. They need her, and she needs them. I love the aspect of the stalker and now the plot twists at the end, so so good. Sometimes, it seemed a little slow and stale mated, but since this a duet, I think It was just her starting to have Vale get to know her alpha suitors. Cliffhanger for sure with this one.
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Reviewed in the United States on September 9, 2024
A
Verified Purchase
Austin & Cambria
Belleville, US
★★★★★ 5
That ending 😫
Format: Kindle
I fell into a false sense of security and really thought this was gearing towards a happy ending. Then I realized there’s no work they don’t punish Andrew. I really liked Vale’s character. I don’t normally read books with pregnancy but going into this knowing she was pregnant made it more enjoyable for me. I loved Bishops devotion to her and her happiness. I also loved that Holt and Mercy couldn’t fight their attraction to her. I love scent matches so very much. I’m so curious to see how this duet will end up. And I need to pay more attention and notice that a book I’m starting is a duet to begin with lol
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Reviewed in the United States on February 21, 2025
S
Verified Purchase
Sarah A
Waukegan, US
★★★★★ 5
oh wow
Format: Kindle
I just knew there was something about Cooper! I’m wondering if he’s about to be included but damn I’m glad he’s at least not a rapist and creepy guy, he just got called on assignment and had to go! This should be interesting! She’s gonna run and then what’s his face is gonna grab her. I’m worried! Wow that was a great book and cliffhanger! Loving this!
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Reviewed in the United States on December 27, 2025
A
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Ashley Morgan
Cuba, US
★★★★★ 5
ABSOLUTELY A MUST for Omegaverse Girls!!!
I ABSOLUTELY LOVE Jillian West and her books!!! I’m so happy I already bought book two and now I have to buy the others for the Assurance Security series!! Not gonna lie Val kind of annoyed me at the beginning but she grew on me!! Her men are chef’s kisses!!! Holt annoys me some but I can let it slide. I already bought part two so I’m going to be reading that in between work phone calls!!!! DON’T TELL MY BOSS 😂😂😂😂
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Reviewed in the United States on September 30, 2025
C
Verified Purchase
Carmen Alicea
Port Orchard, US
★★★★★ 4
Baby bumps and bodyguards
Format: Kindle
Dark, emotional, and unexpectedly tender, Not Ready is an omegaverse romance that delivers found family feels, fierce protectiveness, and a very pregnant heroine who refuses to break. Vale’s on the run from a stalker, but lands in the arms of three private security alphas, cue the swoony tension, fake marriage twist, and slow-burn heat. It’s a little gritty, a little soft, and a whole lot addictive. If you love protective alphas, high stakes, and heroines with quiet strength, this one’s a must-read.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on December 18, 2025

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