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 Jul 22 - Jul 27

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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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Osman
Battle Creek, US
★★★★★ 5
Good
Style: Dress, Color: Gold Tone Stainless Steel
the nicest watch I've used recently
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Reviewed in the United States on April 5, 2026
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D. Jeffrey Eells
San Leandro, US
★★★★★ 4
As described..handsome watch
Style: Dress, Color: Two-Tone Gold/ Blue Dial
Christmas gifts my sons will remember..beautiful watch. Easy to adjust the bracelet if you buy the kit..
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Reviewed in the United States on February 9, 2025
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Christopher A. Smith
Omaha, US
★★★★★ 5
Great affords
Style: Dress, Color: Two-Tone Gold/ Blue Dial
Absolute great watch. It’s perfect for an every day and situation from work to date night. I had to take out 4 links and now it fits perfectly!
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Reviewed in the United States on July 5, 2025
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Brian
Houston, US
★★★★★ 5
SOLID unit and woth the price!
I can't speak for anyone but me, but this is my opinion of this product. I travel a lot. I recently went on a trip to the Mediterranean, (Italy, Spain, France), and needed a new adapter. I'm a computer engineer so I needed something that could handle a MacBook Pro, A windows gaming laptop, Bluetooth headphones, an iPad and 2 phones, (all at the same time). This handled all that with no issues. This would have earned it 4 stars because it's supposed to handle multiple items. The extra star is the fact that it is heavy enough to stay where you place it, has a good cord length, and a nice plug selection. Mine was the 2 prong (Mediterranean)base prong with a U.S 2 prong and a 3 prong version for England, Ireland ETC. The U.S and Brit version fit together like Legos and both fit snugly on the Med prongs. I have used the Med version for 14 constant days with no issues or heating problems. I'm on day 4 in the states and no issues. I can't speak on the Brit adapter yet, but I see no reason this would change. It also has a USB-C slot, in addition to 4 USB slots and the 3 pronged slots for laptops ETC. Please keep in mind, that this is JUST an adapter, it does NOT convert voltages. It's not supposed to.
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Reviewed in the United States on July 2, 2022
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S knight
Charlottesville, US
★★★★★ 5
Brilliant for travelers. Makes life so easy
As travelers know, most hotels in Europe tend to be older (bonus for 100+ years) and may have a single outlet in the room. I looked for something like this IN Europe to no avail. My husband argued that I didn't need such a thing, but we travel with 2-3 laptops and 2-3 cellphones between us if work is involved. This adapter is AWESOME! I can't tell you how much I love it. It gives you extra space for the one wide charger we all are stuck with, without crowding out the middle plug. It put the USB ports above the outlets, not below, so your plugs don't block access. It is lightweight, compact, and has a long enough cord to reach where you need it to go. My husband has now absconded with it and I'm buying a second one. It is worth every penny and every inch of space it takes; both of which are minimal. Fantastic product. NOT paid for review, just LOVE LOVE this thing.
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Reviewed in the United States on June 19, 2023

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