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Ships within 48 hours · Estimated delivery Jul 31 - Aug 5
For Your Every Summer RSVP, with Code: SUMMER15
Description
Holley HP EFI ECU and Harness Kits 550-604NHP ECU AND HARNESS, MPFI, NTK 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
HP ECU AND HARNESS, MPFI, NTK
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 | 550-604N |
Shipping Notes
- Free Standard Shipping on $100+ Orders to the USA.
- Except Preorder products are shipped in 48 hours.
- Delivery to the USA:
- 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
4.8 ★★★★★
Based on 15 reviews
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Product Reviews
★★★★★ 5
Happy pups, happy mama!!!
Flavor Name: Chicken Chips, Size: 1 Pound (Pack of 1)
My pups love these! Great for little dogs!
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on April 15, 2026
★★★★★ 1
Dnt buy!!
Flavor Name: Chicken Chips, Size: 1 Pound (Pack of 1)
These Suck! I have 3 Shih Tzus the one that ate it had a hard time chewing it and the other 2 couldn’t even I had to stick my finger down their mouth cuz they were choking and were trying to spit it out these are not chips they’re more like hard jello the texture is terrible even the color was weird the quality of this product sucks
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on December 3, 2025
★★★★★ 5
My picky dog loves them.
Size: 3.5 Ounce (Pack of 2), Style: Chicken Chips, Size: 3.5 Ounce (Pack of 2), Style: Chicken Chips
I try to give my dog, whom I love so much, the healthies food and treats that i can. She is so very picky and it's difficult to find things she likes. She loves these treats and expectes one every morning. She litterally waites by the pantry door for one. The are healthy Human grate chicken chips. Makes me feel better about giving her a treat. I would Highly recommend.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on May 13, 2026
★★★★★ 5
Treats
Size: 3.5 Ounce (Pack of 1), Style: Chicken Chips
Puppy likes them
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on April 21, 2026
★★★★★ 5
my dog is obsessed with these
Size: 3.5 Ounce (Pack of 1), Style: Chicken Chips
my senior lhasa apso loves these. he smells them and takes it with happiness and excitement! he loves these, can't get enough.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on April 4, 2026
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