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- USA
- CAN
Ships within 48 hours · Estimated delivery Jul 28 - Aug 2
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
4.7 ★★★★★
Based on 30 reviews
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Product Reviews
★★★★★ 5
High quality sheepskin!!
Color: Natural (Yellow-white Ivory), Size: 2' x 3' (Natural), Color: Natural (Yellow-white Ivory), Size: 2' x 3' (Natural)
This sheepskin was purchased as a "chair cover" for my pets. It arrived with very nice packaging, along with detailed care instructions. The sheepskin was advertised as being"not white" online, and the company made very sure to state that the fur has an "off white/yellow" color. That was a little concerning for me, and I wasn't really sure whether it would have an off color, but it arrived exactly as described. There were no obvious discolorations, spots, or blemishes. In fact, it arrived as a soft "off white" color that is very beautiful and exquisite. The fur has a plush, even look, and there is no matting or fuzzy, "neglected teddy bear look" at all!
I actually purchased another brand to see if I could distinguish the difference between the two. This particular sheepskin is by far the better of the two purchases.
FYI: When the package was opened, there was no distinct odor. That's a huge plus!
I will admit that the size was slightly smaller than expected. It really doesn't matter much in the space I'm using it for though. My miniature Dachshund loves it!
If you're trying to find a high quality sheepskin, and you don't need to cover a very large space, this is definitely the one to buy!
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on January 12, 2024
★★★★★ 5
The Quality of the sheepskin is awesome.
Color: Wolf Tip, Size: 2' x 3' (Natural)
This rug is a beautiful specimen of New Zealand sheep. The rug is very very soft, the rug is thick, and the brown tips are fabulous looking. All in all I'm very pleased with this purchase. The size is perfect as it measures 2' x 3'. I would buy again from this seller.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on July 23, 2025
★★★★★ 5
The softness and color
Color: Umber, Size: 2' x 3' (Natural)
Perfect decor for living room and bedroom
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on February 21, 2026
★★★★★ 5
Plush rug that’s super soft. WOW!
Color: Natural (Yellow-white Ivory), Size: 6' x 7' (Natural)
Beautiful and super plush! I use it as an outer blanket when cold weather camping. Like a modern day cave man. One of my favorite purchases. I avoid kneeling on it while it’s on my mattress fearing it might split the hide, or damage the stitching. It fits my queen size camper bed. Cant say enough!
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on December 25, 2025
★★★★★ 5
Big Investment for a Lifetime of Quality
Color: Natural (Yellow-white Ivory), Size: 2' x 3' (Natural)
Several reviews mentioned a smell lingering with the sheepskin even after being unpacked a few days. I did notice the smell when I unpacked it, but I would expect a slight odor from such an item. It was not overpowering and is completely gone after one month of having it laid out on a chest in our bedroom. It is very functional, can be sat on, knelt on, etc, but is easily brushed off and looks great! The quality is very good…someone in my family is on it every night, and we have experienced no shedding whatsoever.
Although the price is a big investment initially, I believe the quality is worthy. We plan to enjoy this beautiful sheepskin for a lifetime!
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on January 31, 2025
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