HOLLEY 558-104 Mpfi Harness 090127666746

( Brand: Holley ), ( Type: Engine Wiring Harnesses ), ( Item Height: 4.000 ), ( Item Length: 11.00 ), ( Item Width: 10.500 ), ( Universal Fitment: Yes ), ( California Prop 65 Warning: False ), ( UPC: 090127666746 ), ( Manufacturer Part Number: 558-104 )

Review HOLLEY Universal Mpfi Main Harness

The Holley 558-104 MPFI (Multi-Point Fuel Injection) Harness is a crucial component for any engine setup that utilizes Holley's Electronic Fuel Injection system. This harness is specifically designed to work with Holley's 550-1101, 550-1103, or 550-1106 MPFI distributors.

Measuring approximately 54 inches long, this harness provides ample length to accommodate various engine installations. Constructed of high-quality, flexible insulated wire, this harness ensures reliable power and ground connections to the distributor, coil packs, and fuel injectors.

The 558-104 harness features a multi-pin connector that attaches to the distributor, providing power and ground circuits for the distributor cap and rotor. Additionally, it includes eight individual wires for the fuel injectors, each terminated with a DTM-style connector for easy attachment to the corresponding injector.

Each wire in the harness is color-coded and clearly labeled for easy identification and installation. The power and ground wires are red and black, respectively, while the fuel injector wires are numbered and color-coded according to their corresponding injector location.

The Holley 558-104 MPFI harness is a direct-fit replacement for original equipment distributor harnesses and is compatible with most domestic and import vehicles. It is also designed to work with both 12-volt and 24-volt systems, making it a versatile choice for a wide range of applications.

Installation of the harness is straightforward and can be completed in a relatively short amount of time. Holley provides detailed instructions and diagrams to guide users through the installation process. Overall, the Holley 558-104 MPFI harness is an essential accessory for any engine builder or tuner seeking a reliable, high-performance fuel injection system.

The Holley 558-104 MPFI (Multi-Point Fuel Injection) harness is a popular choice among car enthusiasts and mechanics for its ability to provide reliable fuel delivery in high-performance applications. However, like any automotive part, it comes with its pros and cons.

1. Compatibility: The Holley 558-104 MPFI harness is designed to work with various Holley EFI systems, making it a versatile option for different types of vehicles.

2. Reliability: Holley is a well-known brand in the automotive industry, and this harness is no exception. It is built to withstand the rigors of high-performance racing and daily driving.

3. Easy Installation: The harness comes pre-terminated, making the installation process simpler and more straightforward compared to other fuel injection systems.

4. Flexibility: The harness can be configured to work with different fuel pressure regulators and fuel pumps, allowing users to choose the ones that best fit their specific application.

1. Cost: The Holley 558-104 MPFI harness is more expensive than some aftermarket alternatives, which may deter some buyers.

2. Complexity: While the pre-terminated harness simplifies the installation process, it can also make troubleshooting more difficult if a problem arises.

3. Limited Customization: Although the harness is flexible in terms of fuel pressure regulators and fuel pumps, it may not offer as much customization as other, more advanced EFI systems.

The Holley 558-104 MPFI harness is a reliable and versatile option for those looking to upgrade their vehicle's fuel delivery system. Its compatibility with various Holley EFI systems, ease of installation, and robust construction make it a popular choice among car enthusiasts and mechanics. However, its higher cost compared to some alternatives and limited customization options may deter some buyers. Ultimately, the decision to purchase the Holley 558-104 MPFI harness depends on the specific needs and budget of the user.

If you're looking for a reliable and easy-to-install fuel injection harness for your high-performance vehicle, the Holley 558-104 MPFI harness is a solid choice. Its compatibility with various Holley EFI systems and robust construction make it a worthwhile investment for those who prioritize reliability and ease of use. However, if you're on a tight budget or require more customization options, you may want to explore other aftermarket alternatives.

part # 558104 prices

• $450.00-$549.95

specifications injectiopug:

• brand: Holley
• type: Engine Wiring Harnesses
• item height: 4.000
• item length: 11.00
• item width: 10.500
• universal fitment: Yes
• california prop 65 warning: False
• upc: 090127666746
• manufacturer part number: 558-104

returns injectiopug:

• policy: Returns Accepted
• time: 30 Days
• paid by: Seller

offer injectiopug:

• availability: In Stock
• sold: 0
• started: October 30, 2025
• options: Ship-to-home

seller injectiopug:

• rating: 99.4%
• # reviews: 335185

general injectiopug:

• condition: New
• Air Fuel Delivery > Fuel Injection Parts > Additional Fuel Injection Parts

payments injectiopug:

• credit card: Discover
• other
• wallet: Google-pay

shipping injectiopug:

• type: Fixed
• transit: 4-8 Days
• service: UPS Ground
• cost: $0.00
• class: Standard
• carrier: UPS

Holley 558-104 Is Similar To:

• Holley 558-452 - Can Adapter Harness 4ft Male To Female (49.5% similar) $28.50–$59.55. (February 22nd, 2025)
• Holley Efi 558-418 Gen Iii Hemi Drive-by-wire Harness - Late Pedal (48.1% similar) $255.95–$271.82. (March 11th, 2025)
• Holley Efi 558-209 Ford V8 Injector Harness (58.8% similar) $169.00–$281.57. (April 11th, 2025)
• Holley 534-45 Throttle Body Wiring Harness (57.1% similar) $6.95–$27.50. (April 14th, 2025)
• Holley Efi 558-454 Can Adapter Harness 12ft (56.5% similar) $94.49–$113.88. (April 14th, 2025)
• Holley Efi 558-134 Ls2/3/7 58x/4x Engine Main Harness - Extended Length (53.1% similar) $688.95–$704.09. (April 15th, 2025)
• Holley 558-200 Performance Bosch Style Connector Harness (53.1% similar) $149.99–$215.57. (April 19th, 2025)
• Holley 558-425 - Can Extension Harness (62.5% similar) $67.49–$90.47. (May 4th, 2025)
• Holley 558-204 - Unterminated Injector Harness Kit (60.9% similar) $230.95. (May 18th, 2025)
• Holley Efi 558-430 Can Adapter/power Harness (58.1% similar) $43.02. (May 18th, 2025)
• Holley 534-56 Throttle Body Wiring Harness (57.1% similar) $43.95–$44.82. (May 28th, 2025)