Terminator X gives Gen III GM truck engines a self-learning standalone EFI system without the cost or complexity of a hacked junkyard ECU. It features real-time fuel learn, high-impedance injector drivers, an integrated 1bar MAP sensor, and four programmable inputs and outputs for accessories like electric fans, boost control, or progressive nitrous. This kit ships with a USB/CAN tuning cable instead of the handheld LCD, so setup and tuning happen through Holley's free Terminator X laptop software.
Key Features:
- Built for GM LS/truck engines with a 24x crank reluctor and Multec 2 injectors
- Real-time fuel map learn removes the guesswork from base fuel table tuning
- High-impedance injector drivers safely power most stock LS and Holley EFI injectors (not compatible with low-impedance injectors)
- Bosch LSU 4.9 wideband oxygen sensor included for accurate AFR readings and precise tuning
- Integrated 1bar MAP sensor with vacuum hose adapters (1/8", 1/4", 3/16")
- 4 outputs (Ground, PWM) for fans, boost control, nitrous control, IAC kits, and more
- 4 inputs (12v, Ground, 5v, Frequency) for extra pressure sensors or activation triggers
- Boost control strategies: Boost vs Time, Gear, RPM, Speed, plus boost safeties
- Nitrous control: single channel wet or dry, progressive or non-progressive, with rich/lean safeties
- On-board diagnostic LEDs for ECU power, engine run, wideband status, TPS calibration, crank signal, and cam signal
- Advanced custom tables (4x 1D, 1x 1D per-gear, 4x 2D, 1x 2D per-gear) for flex fuel offset or custom safety tables
- Plug-and-play compatible with Holley EFI gauges, shift lights, modules, and digital/pro dashes
- Compact ECU size mounts virtually anywhere (LEDs must face up)
- Free EFI tuning software for full laptop control of the system
Specifications:
- Engine/Platform: Gen III GM Truck 4.8L/5.3L/6.0L
- Crank Reluctor: 24x
- Cam Signal: 1x
- Injector Connector: Multec 2
- Throttle Body Control: DBC (mechanical throttle body; Drive-By-Wire: No)
- Transmission Control: None
- MAP Sensor: Integrated 1bar
- Handheld Included: No — USB/CAN tuning cable included instead
- What's Included: 24x LS engine main harness, Multec 2 injector harness, Terminator X ECU, ECU main power harness, Bosch LSU 4.9 wideband oxygen sensor, input/output harness, vacuum adapters
- Part Number: 550-904T
Terminator X ECUs must be mounted with the diagnostic LEDs facing up. Because this kit uses the USB/CAN cable rather than the handheld, initial setup requires the free Terminator X laptop software.
FAQ
What engines does the 550-904T Terminator X system support?
Gen III GM truck engines — 4.8L, 5.3L, and 6.0L — with a 24x crank reluctor, 1x cam signal, and Multec 2 injectors.
Does this kit include the handheld tuner?
No, this version includes a USB/CAN tuning cable instead of the 3.5" handheld, and requires the free Terminator X laptop software for setup.
Is this a drive-by-wire system?
No, this kit is set up for a mechanical (DBC) throttle body, not drive-by-wire.
Does it control an automatic transmission?
No, this kit does not include transmission control.
What injectors does it support?
Multec 2 connector, high-impedance injectors — most stock LS and Holley EFI injectors work, but it will not control low-impedance injectors.