This Terminator X system gives GM Gen IV LS engines (4.8/5.3/6.0 truck and LS2/LS3) real-time fuel learn, high-impedance injector drivers, an integrated 1-bar MAP sensor, and full ignition timing control in one compact, throttle-body-mounted ECU. It ships loaded with base maps for common LS combinations to get a stock engine running quickly, while still offering the tuning depth needed for boosted or nitrous-fed builds. Instead of a handheld display, this kit includes a USB/CAN tuning cable, with setup and tuning handled through Holley's free Terminator X software.
Key Features:
- Designed for GM LS engines with 58x crank, 4x cam signal, and EV6 (USCAR) injectors
- Real-time fuel map learn removes much of the guesswork from base fuel table tuning
- High-impedance injector drivers safely power most stock LS injectors and Holley EFI injectors (does not control low-impedance injectors; injector support chart included in instructions)
- Bosch LSU 4.9 wideband oxygen sensor relays AFR data to the ECU for accurate, precise tuning
- Integrated 1-bar MAP sensor with vacuum hose adapters (1/8in, 1/4in, and 3/16in) included
- 4 programmable inputs (12V, ground, 5V, frequency) for pressure sensors, nitrous activation triggers, or a trans-brake
- 4 programmable outputs (ground, PWM) for fans, boost control, nitrous control, idle air control, and more
- Boost control strategies: boost vs. time, boost vs. gear, boost vs. RPM, boost vs. speed, plus boost safeties
- Nitrous control: single channel, wet or dry, progressive or non-progressive, with rich/lean safeties and closed-loop AFR targeting
- On-board diagnostic LEDs for ECU power, engine run, wideband status, TPS calibration, crank signal, and cam signal
- Advanced programmable tables: four 1D tables, one 1D per-gear table, four 2D tables, and one 2D per-gear table for custom uses such as a flex-fuel sensor offset table or a fuel/oil pressure safety
- Compact ECU can be mounted virtually anywhere, provided the diagnostic LEDs face up
- Plug-and-play compatible with Holley EFI gauges, shift lights, and digital/Pro Dash displays (Holley part numbers 553-106, 553-111, and 553-112)
- Free EFI tuning software included for full laptop-based control
Specifications:
- Product Type: EFI System (Terminator X)
- Engine: GM Gen IV LS, 4.8/5.3/6.0 Truck & LS2/LS3
- Ignition Type: GM LS 58x
- Crank Reluctor: 58x, 4x cam
- Injector Connector: USCAR (EV6)
- Handheld Included: No (USB/CAN tuning cable)
- Drive-By-Wire: No
- Transmission Control: None
- MAP Sensor: 1 Bar
- Includes: 58x/4x LS main harness, EV6 injector harness, ECU, ECU main power harness, Bosch LSU 4.9 wideband O2 sensor, I/O harness, vacuum adapters
- Part Number: 550-905T
ECU is designed to be mounted with its diagnostic LEDs facing up. This kit does not include transmission or drive-by-wire throttle body control — for those features, Holley's Terminator X Max is the step-up option.
FAQ
What engines does the Holley Terminator X 550-905T support?
GM Gen IV 4.8/5.3/6.0 truck engines and LS2/LS3 engines with a 58x crank / 4x cam signal and EV6 (USCAR) injectors.
Does this kit include a handheld display?
No. This Terminator X kit uses a USB/CAN tuning cable instead of a handheld, so initial setup and tuning run through Holley's free Terminator X software.
What kind of injectors will this ECU control?
High-impedance injector drivers that safely power most stock LS injectors and Holley EFI injectors. It will not control low-impedance injectors; an injector support chart is included in the instructions.
Can this ECU control boost or nitrous?
Yes. It includes boost control strategies (boost vs. time, gear, RPM, and speed, with safeties) and single-channel wet or dry nitrous control, progressive or non-progressive, with AFR safeties.
How should the ECU be mounted?
With the diagnostic LEDs facing up, per Holley's installation guidance.
Does the Terminator X support transmission or drive-by-wire control?
No, this version (550-905T) handles fuel and spark only, with no transmission or drive-by-wire throttle body control. Holley's Terminator X Max adds those features.
