GM LS 24x Crank, 1x Cam - 4.8/5.3/6.0 Truck Engines - 4L60/4L80 Transmission Control, No Laptop Required, 3.5" Touchscreen Included

Part #: 550-917

Brand: Holley EFI


Take control of your LS engine with Terminator X Max! Don't settle for a junkyard ECU with a cumbersome tuning interface when you can have complete control of your engine, self-learning fuel strategies and the proven, race-winning technology of Holley EFI at a budget-friendly price!
Terminator X Max features real-time fuel learn, high impedance injector drivers, an integrated 1bar MAP sensor, and 4 programmable inputs and outputs. The inputs and outputs are ideal for electric fans, boost control solenoids, progressive nitrous control, and much more. Part number 550-917 also has 4L60 or 4L80 Transmission control. Terminator X Max comes fully loaded with base maps for common LS engine combinations to get you out of the garage and on the road/track fast. The 3.5" touch screen LCD handheld contains an easy to use calibration wizard as well as tuning and gauge display functions. Also included is Holley EFI's industry-leading, easy to use software suite that allows full laptop access for advanced users. Whether you are building a budget beater or a boosted race car, Terminator X MAX has the features and technology you need at a price that won't break the bank!

Terminator X Max Early Truck 24x/1x LS MPFI Kit with Transmission Control

Part #: 550-917
  • Length: 12.25"
  • Width: 11"
  • Height: 8"
  • Emissions Code: 4
  • Prop 65: No
Installation Notes:

Terminator X ECU's are designed to be mounted with the LED's facing up.


  • For GM LS 4.8/5.3/6.0 Truck Engines with 24x crank reluctor
  • Transmission Control
  • and Multec 2 Injectors
  • Real-Time fuel map learn
  • takes the guess work out of tuning your base fuel table.
  • High Impedance Injector Drivers will safely power most Stock LS injectors
  • and Holley EFI Injectors. Injector support chart provided in the instructions (Will not control Low Impedance Injectors)
  • All of the new Terminator X Max systems utilize the Bosch LSU 4.9 wideband to relay AFR information to the ECU for accurate reading and precise tuning control.
  • On-Board 1bar MAP sensor
  • is perfect for N/A or Nitrous engine combos. If your combination requires a 2+Bar
  • we recommend GM 12592525
  • and our adapter part number 558-416.
  • MAP Sensor vacuum hose adapters (1/8th – ¼ and 3/16ths)
  • 4 Inputs – 12v
  • Ground
  • 5v
  • and Frequency
  • for things such as additional pressure sensors
  • or activation triggers for nitrous activation
  • or a trans brake
  • 4 Outputs – Ground
  • PWM -
  • for accessories such as; fans
  • boost control
  • nitrous control
  • IAC Kit
  • and More
  • Boost Control – Boost vs Time
  • Boost vs Gear
  • Boost vs RPM
  • Boost vs Speed
  • Boost Safeties
  • Nitrous Control – Single Channel of Wet or Dry
  • Progressive or Non-Progressive
  • Rich/Lean Safeties
  • and target Closed Loop AFRadjustable through included 3.5” full color touchscreen
  • base tune easily created via handheld Wizard!
  • Advanced Tables – 4x 1D Tables
  • 1x 1D per Gear Table
  • 4x 2D Tables
  • 1x 2D per Gear Table
  • can be used for any custom tables you can dream up
  • such as Flex Fuel Sensor Offset Table
  • or a custom fuel or oil pressure safety!
  • On-Board Diagnostic LEDS for: ECU Power – Engine Run – Wideband Status – TPS Calibration – Crank Signal –Cam Signal. Allow you to identify any Critical engine issues at a glance
  • The included 3.5” Touchscreen Handheld contains a calibration wizard
  • that allows you to quickly build a base tune for any LS engine. Additionally the handheld provides internal data-logging and a fully customizable gauge display.
  • The compact ECU size allows you to mount it virtually anywhere. Remember
  • diagnostic LEDS must face up!
  • Plug and play compatible with more Holley EFI accessories such as; analog style gauges
  • shift lights
  • various modules
  • and coming soon
  • 12.3” digital dash support!
  • Free EFI Tuning Software for complete control of your Terminator X power plant