Holley Terminator X LS ECU and Harness

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  • Regular price $1,427.95
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Holley Terminator X GM LS1/LS6, 4.8/5.3/6.0 and LS2/3 -3.5" Touchscreen Included



LS engine owners rejoice! The high price of standalone LS engine management have been Terminated!

Introducing Terminator X and Terminator X Max. Two HOT new powertrain management systems from Holley that offer plug and play control for most LS engines starting at just $999.

Why settle for a junkyard ECU with a cumbersome aftermarket tuning interface when you can get complete control of your engine, self-learning fuel strategies and the proven, race winning technology of Holley EFI for under a grand!

Terminator X 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.

Terminator X products come fully loaded with base maps for common LS engine combinations to get you out of the garage and on the road / track fast. The included 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. All of the new Terminator X systems utilize the Bosch LSU 4.9 wideband to relay AFR information to the ECU for accurate reading and precise tuning control. Whether you are building a budget beater or a boosted race car, Terminator X has the features and technology you need at a price that won't break the bank. Terminator X kits are also compatible with most Holley EFI accessories such as; analog style gauges, shift lights and various modules, and coming soon, digital dash plug and play capability!

The standard Terminator X will not control Drive-by-wire (DBW) or auto transmission control. If you need these functions check out the Terminator X MAX- contains all of the features above, but also brings single drive-by-wire throttle body control, and electronic transmission control to the party!


  • For GM LS1/LS6 and Truck (Vortec) 4.8/5.3/6.0 engines with 24x crank reluctor AND LS2/3 engine with 58x Crank Reluctor (select the appropriate kit) WILL NOT CONTROL DRIVE BY WIRE!
  • Genuine Bosch LSU 4.9 Wideband
  • 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 AFR
  • Advanced Tables – 4x 1D Tables, 1x 1D per Gear Table, 4x 2D Tables, 1x 2D per Gear Table
  • 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
  • Fully adjustable through included 3.5” full color touchscreen, base tune easily created via handheld Wizard!
  • Intergrated Datalogging to the 3.5” Handheld SD Card
  • Free EFI Tuning Software for complete control of your Terminator X power plant

 Part numbers 550-903, 550-904,  550-905