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- USA
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Ships within 48 hours · Estimated delivery Jul 10 - Jul 15
For Your Every Summer RSVP, with Code: SUMMER15
Description
Holley Terminator X Engine Management Systems 550-903TERMINATOR X MPFI, LS1 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! Terminator X features real time fuel learn, high impedance injector drivers, an integrated 1bar MAP sensor, and 4 programmable inputs and outputs. The
TERMINATOR X MPFI, LS1
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! 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 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 has the features and technology you need at a price that won't break the bank!
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 – 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
- 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
- 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
- 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.
Application
- 1998 - 2002 Chevrolet Camaro
- 1997 - 2004 Chevrolet Corvette
- 1998 - 2002 Pontiac Firebird
Specs
| Brand | Holley EFI |
|---|---|
| Crank Reluctor | 24x |
| Emission Code | 3 |
| Ignition Type | GM LS 24x |
| Injector Connector | Jetronic / Minitimer (Bosch) |
| Product Type | Terminator X LS MPFI |
| Terminator LS Options | Fuel, Spark |
| Part Number | 550-903 |
Shipping Notes
- Free Standard Shipping on $100+ Orders to the USA.
- Except Preorder products are shipped in 48 hours.
- Delivery to the USA:
- Standard Shipping : 3-10 business days
- If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
- We offer a 30-day return/exchange service after receiving.
- Final sale items are not eligible for returns or exchanges.
- To process your return/exchange, please contact us at [email protected]
- Please click here for more details>>> Return & Exchange Policy
4.8 ★★★★★
Based on 1484 reviews
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Product Reviews
★★★★★ 5
Snoopy Pepsi
Color: Stainless Steel/Blue/Stainless Steel/red-blue, Color: Stainless Steel/Blue/Stainless Steel/red-blue
Such a sharp looking watch!
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on January 27, 2026
★★★★★ 1
Poor design and final product
Color: Stainless Steel/Black/Stainless Steel/Red Black
The watch looks nice. That is the only good part. It works by being wound by motion when one wears it. Should I do jumping jacks to keep it wound? I dont sleep with it on! Every morning it is not running and the date is wrong until it gets shaken. The band is hard to get it on and hard to get it to come off. It sometimes falls off though. I was trying to replace my older Timex watch and now I am back to wearing the old one that never had these problems.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on May 23, 2022
★★★★★ 5
Love it! Though overpriced at MSRP
Color: Stainless Steel/Blue/Stainless Steel/red-blue, Color: Stainless Steel/Blue/Stainless Steel/red-blue
I love this watch! I had it in my cart for weeks, waiting for an excuse to buy it. The thing holding me back was the $299 MSRP and price on Amazon. I noticed it went down to $200 while I was shopping on Amazon, so I immediately completed the purchase.
At Grey Market retailers, this goes for about $160 (which I think is the perfect price). Unfortunately the Snoopy edition proved difficult to find at that price as it was sold out everywhere. Even sold out on the Timex website at $299.
I still recommend it, but it's all about what you're willing to pay. For me, $200 was an acceptable price and worth it to me. As a snoopy lover, I'll give this to my kids one day! Not a doubt in my mind it won't last for a very long time as it uses a Citizen movement!
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Reviewed in the United States on June 30, 2024
★★★★★ 2
Thought it would be better quality
Color: Stainless Steel/Black/Stainless Steel/Red Black
It's only okay, I thought it would age better.
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Reviewed in the United States on February 8, 2026
★★★★★ 5
Good watch
Color: Brown
Ticking right along, great work watch.
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Reviewed in the United States on November 18, 2025