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-10% Terminator X MPFI Kit for Universal Applications

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:

  • *Except "Tuner" versions
  • **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
  • *Except "Tuner" versions

Unique To The Terminator X MPFI Kit for Universal Applications

Holley provides many features unique to Universal 4, 6, or 8 Cylinder Even-Fire Four Stroke Engines 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 GM 4L60E, 4L65E, early 4L70E, 4L80E, and 4L85E transmissions*
  • Drive-By-Wire harness for GM LS DBW throttle body*
  • EV1-style Injector harness
  • *Transmission Control Versions Only
  • *Drive-By-Wire Control Versions Only

Choose From Four Different Versions of the Terminator X MPFI Kit for Universal Applications

Part NumberManuf.EngineECUInjector
550-936Universal4, 6, or 8 Cylinder Even-Fire Four Stroke EngineXEV1NoNo
550-950Universal4, 6, or 8 Cylinder Even-Fire Four Stroke EngineX MaxEV1NoYes
550-942Universal4, 6, or 8 Cylinder Even-Fire Four Stroke EngineX MaxEV1YesNo
550-959Universal4, 6, or 8 Cylinder Even-Fire Four Stroke EngineX MaxEV1YesYes

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.


  • *Included in "Tuner" versions

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 Universal Engine

Boost ControlYes (Requires Additional Hardware)
DIS OutputsEight
FamilyTerminator X
Fueling StrategySpeed Density, Alpha-N, or Combination
Includes Power HarnessYes
Injector DriversFour
Internal Datalogging4GB
Nitrous ControlYes (Requires Additional Hardware)
Number of Cylinders4, 6, or 8 (Even Fire Only)
User Configurable I/OYes
Water-Methanol ControlYes (Requires Additional Hardware)
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 (Except Tuner Version)
Internal StorageYes (SD Card)
Harness TypePower Harness, Main Harness, TBI Injector Sub-Harness, I/O Harness, Ignition Adapter. Transmission Harness (Transmission Control Versions Only), DBW Harness (DBW Versions Only)
Crank Timing
Sensor Harness IncludedNo (Ignition Adapter Only)
Type1 BAR MAP (Integrated in ECU); Wideband O2
Also IncludedI/O Adapter Harness
ApplicationUniversal 4, 6, or 8 Cylinder Even-Fire Four Stroke 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 Universal Applications

  • Views: 39950
  • Brand: Holley EFI
  • Product Code: 550-936 | 550-942 | 550-950 | 550-959
  • Availability: In Stock
  • $1,587.00
  • $1,427.95

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