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Ignitions and Electrical› Computers, Chips, Modules and Programmers
Holley
Terminator X MPFI GM LS1/LS6
SKU: H00E 550-903T
Moderate — 2–4 hours
Overview
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Part #: 550-903T
Take control of your LS engine with Terminator X! 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!
Features:
- For GM LS1/LS6 engines with 24x crank reluctor - with EV1 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 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 - ┬╝ 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
- 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, 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
- Includes CAN/USB tuning cable allowing you to configure your ECU and Tuning the engine in real time.
- 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
- Includes: 24x LS Engine Main Harness - EV1 Injector Harness - Terminator X ECU - ECU Main Power Harness - Bosch LSU 4.9 Wideband Oxygen Sensor - Input/Output Harness - and assorted vacuum adapters.
24x Crank - 1x Cam - EV1 Injectors - USB/CAN Tuning Cable
Product descriptions are provided by our supplier partners and may not always be perfectly accurate. Not sure this fits? or call (760) 282-4645 and we’ll verify before you order.
Fitment
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Specifications
| Brand | Holley |
| Part Number | H00E 550-903T |
| Weight | 9.0 lb |
Videos
Terminator X Full Install and Overview
How To: Install Terminator X EFI on any LS Engine
Holley Terminator X Max install for newbies!
Don't Buy A Holley Terminator X Before Watching This Video
The Best Budget LS Swap ECU 2019 (Holley Terminator X )
Terminator X EFI for LS Engines
Holley Terminator X Just Got a Major Upgrade
Reviewing Holley's Terminator X EFI
BUDGET HOLLEY EFI DIGITAL DASH! CHEAP AND EASY TO INSTALL! E36 Turbo LS Swap Ep: 38
LS 5.3 Swap, Holley Terminator X Max installation on 1981 El-Camino with 4L60E transmission.
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Built for enthusiasts. Every order is backed by our 30 day return window on eligible items. Unused and uninstalled products may be returned with approved RMA and no restocking fees when received in new condition. Orders placed through the MOTORMIA app with a complete build qualify for our Fitment Guarantee — free return shipping if the part doesn’t fit your exact setup. The guarantee covers fit only; installation must follow manufacturer instructions, and we recommend a qualified shop for parts marked Difficulty 4–5.
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