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-10% Terminator X MPFI Kit for Ford V8 302, Windsor & Big Block Engines

What's Terminator X?

Holley's Terminator X family of EFI Systems are standalone engine management systems that closely replicate some of Holley's most advanced engine management systems but at a much more budget-friendly price. This PDF gives a highly detailed comparison of the Terminator X and X Max to engines built using the Holley HP and Dominator ECUs. To summarize, Holley was able to leave out some features found to be less-necessary by the majority of users and, in doing do, slash the price of a full-featured EFI System by half.  If you're switching your carbureted engine to multi-point EFI or are swapping a fuel-injected engine into your ride and need to stay on a budget, this is the EFI system for you.

Here are some of the features that are included in each Terminator X kit:

  • **Requires hardware not included with Terminator X system to implement
  • **X Max Version Only

Different Terminator X EFI Systems For Different Applications

Yes, there are quite a few different Terminator X EFI System--nearly 100 with more on the way.  All Terminator X systems include either a Terminator X or Terminator X Max ECU. The Terminator X Max ECU provides connectivity for transmission control and drive-by-wire harnesses and is included only in those kits that require one or both of these features. Both ECUs include an on-board 1-BAR MAP sensor or you can add an external MAP sensor for boosted applications. On-Board Diagnostic LEDs display the status of ECU Power, Engine Run, Wideband Status, TPS Calibration, Crank Signal, and Cam Signal

In addition to the ECU the kit all Terminator X / X-Max systems include the following:

  • ECU Power Harness
  • Application-Specific Main Harness
  • 3.5-inch Touchscreen LCD Display with Setup Wizard app
  • Custom 4-input / 4-output harness pre-configured for two Electric Fans, A/C Kick, and A/C Shutdown
  • Bosch LSU 4.9 Wideband O2 Sensor

Unique To The Terminator X MPFI Kit for Ford V8 302, Windsor & Big Block Engines

Holley provides many features unique to the Ford Windsor and Big Block Engine and Ford Foxbody w/ 5.0 Engine that make this EFI system a breeze to install and configure and powerful to operate.

  • Custom sensor setup and connectors for commonly available sensors and IAC make sourcing and installing reliable parts a breeze
  • Holley Universal 10-pin Ignition Connector is plug-and-play with Holley's Dual Sync Distributor as well as other popular Holley ignition kits and adapters.
  • Transmission harness for Ford 4R70W and 4R75W transmissions from 1998 and up*
  • Transmission harness for GM 4L60E, 4L65E, early 4L70E, 4L80E, and 4L85E transmissions*
  • Two Four-Channel Coil Driver Modules for Ford Ignition Coils
  • EV1 Injector harness
  • *Transmission Control Versions Only

Choose From Six Different Versions of the Terminator X MPFI Kit for Ford V8 302, Windsor & Big Block Engines

Part NumberManuf.EngineECUInjector
550-937Ford302, Windsor and Big Block EngineXEV1NoNo
550-943Ford302, Windsor and Big Block EngineX MaxEV1Yes1No
550-944Ford302, Windsor and Big Block EngineX MaxEV1Yes2No
550-945Ford302, Windsor and Big Block EngineX MaxEV1Yes3No
550-937FFordFoxbody w/ 5.0 EngineXEV1NoNo
550-943FFordFoxbody w/ 5.0 EngineX MaxEV1Yes1No

1: Includes harness for 92-97 4R70W transmission
2: Includes harness for 98+ 4R70W transmission
3: Includes harness for Pre-2009 GM 4L60E/4L80E transmission

How is the Foxbody Version Different?

The "F" versions of these kits are made specifically for Foxbody Mustang owners. These kits include a lengthened main harness and custom ECU bracket that allows the ECU to be custom-mounted under the seat. Easy and professional-looking installation!  Holley also includes the Ford TFI ignition adapter that makes controlling ignition timing a breeze (requires the original TFI ignition or variant there-of.)

What Else Will I Need?

Required:  EFI Fuel System with

  • EFI Fuel Pump (Many great options here)
  • Pre- and Post-Pump Filters
  • Fuel Pressure Regulator
  • Associated Hose, Hose Ends, Clamps, Adapters, Etc.


Not Sure? Review this product documentation before you buy!

Quickstart Manual
Holley Terminator X and X Max EFI Systems

Tuning Manual
Holley Terminator X and X Max EFI Systems

Wiring Diagram
Holley Wiring Harness for Ford 5.0 Engine in Foxbody Mustang

Harness Manual
Holley Wiring Harness for Ford 5.0 Engine in Foxbody Mustang

Boost ControlYes (Requires Additional Hardware)
FamilyTerminator X
Fueling StrategySpeed Density, Alpha-N, or Combination
Includes Power HarnessYes
Injector DriversEight High Impedance
Internal Datalogging4GB
Nitrous ControlYes (Requires Additional Hardware)
Number of CylindersEight
User Configurable I/OYes
Water-Methanol ControlNo
Displays And Controllers
Auto BrightnessNo
CAN Bus CapableYes (Specific to Holley ECUs Only)
Case/Bezel FinishBlack
ConfigurableMonitor dozens of pre-configured metrics provided by the ECU, including sensors, air/fuel ratio, switched outputs, drive-by-wire data, and more.
Data LoggingYes
Display TypeLCD
FunctionsSetup, Monitor, Tuning
Gauge/Display Size3.5 Inch Rectangular
Internal StorageYes (SD Card)
Harness TypePower Harness, Main Harness, Injector Sub-Harness, I/O Harness, Ignition Adapter. Transmission Harness (Transmission Control Versions Only), DBW Harness (DBW Versions Only)
Crank Timing
Sensor Harness IncludedFoxbody Versions Only. Others include only an adapter harness for sensing engine RPM.
TypeECU-mounted 1 BAR MAP, Wideband O2
Also IncludedI/O Harness
ApplicationFord Windsor and Big Block Engine and Ford Foxbody w/ 5.0 Engine
Emission Code3 - This part is legal for sale and use on Uncontrolled (Non-Emissions Controlled) Vehicles and Racing Use Only Vehicles.
Unit of SaleKit

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Terminator X MPFI Kit for Ford V8 302, Windsor & Big Block Engines

  • Views: 48374
  • Brand: Holley EFI
  • Product Code: 550-937(F) | 550-943(F) | 550-944 | 550-945
  • Availability: In Stock
  • $1,587.00
  • $1,427.95

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