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Description
Holley Terminator X MAX Engine Management Systems 550-918TERMINATOR X MAX MPFI W TRANS CONTROL Take control of your LS engine with Terminator X Max! 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 Max features real time fuel learn, high impedance injector drivers, an integrated 1bar MAP sensor, and 4 programmable
TERMINATOR X MAX MPFI W/TRANS CONTROL
Take control of your LS engine with Terminator X Max! 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 Max 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. Part number 550-918 also has 4L60E or 4L80E Transmission control. Terminator X Max 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 MAX has the features and technology you need at a price that won't break the bank!
Features:
- Designed for GM LS 4.8/5.3/6.0 LS Truck Engines and LS2/LS3 with 58x Crank, 4x Cam and 4L60E/4L80E transmissions, and EV6 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 Max 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
- 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, 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: 58x/4x LS Engine Main Harness - EV6 Injector Harness - 4L60E/4L80E Transmission Control Harness - Terminator X MAX ECU - ECU Main Power Harness - Bosch LSU 4.9 Wideband Oxygen Sensor - Input/Output Harness - and assorted vacuum adapters.
Specs
| Brand | Holley EFI |
|---|---|
| Crank Reluctor | 58x |
| Emission Code | 3 |
| Ignition Type | GM LS 58x |
| Injector Connector | USCAR (EV6) |
| Product Type | Terminator X Max LS MPFI |
| Terminator LS Options | Fuel, Spark, Transmission |
| Part Number | 550-918 |
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
4.2 ★★★★★
Based on 691 reviews
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Product Reviews
★★★★★ 5
Very Good watch
Color: Blackout
The one complaint I hear most often about this watch is it is harder to see in lower lighted conditions. Yes that is true BUT IT HAS INDIGLO so It is not a problem. Most of the time you don't need to turn the light on though. You usually can make out what it says even without the light. Usually if you can't see it then a slight angle change and you can see the time. If you still can't see it....it does have indiglo. It really takes no time at all to hit the button and you can see in any light condition. I have been looking at watches to buy for some time now and have looked at a lot of them. When I first got this in the mail I thought it to be small. I was comparing it to the G-shock series. The ones I was looking at the most was the XL ones. So yes it is small compared to the XL G-shocks. I have an XL watch and found that it gets in the way. When ever my wrist gets bent backwards my hand presses against the watch and restricts my movement that way. This is really the perfect size. One common complaint with Ironman's is they have started integrating the band with the watch. So when the band breaks, which they often did, the watch was useless cause you couldn't replace the band. This one has the replaceable band but still manages to have that integrated look, very nice. I really don't expect the band to break any time soon though. It feels very durable and thick. One thing about the band that I really like is at the end of the band. It has two little "nubbins" that lock in the that loop that holds the excess band in. They really work well. Every watch I have ever owned that little loop moves and releases the excess and then you have to fix it. It has yet to slip off once. All in all in is very nice watch. It works well, the price is very reasonable, The band is replaceable and durable, and the blacked out look is very nice. I love this watch.
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Reviewed in the United States on June 17, 2014
★★★★★ 5
Favorite daily use watch
Color: Blackout
Literally the best watch ever. Super durable. This is my second or third one. The Battery will last years at a time and doesn't take an expensive battery. The buttons are laid out intelligently and are intuitive to use. The strap will eventually break before the watch itself will. Though it has all the stop watch features, it's not too bulky. Also, it takes the time easily and keeps it.
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Reviewed in the United States on December 19, 2025
★★★★★ 5
Great product
Color: Black/Yellow Accent
Watch and service was great. I would recommend product to others.
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Reviewed in the United States on May 27, 2026
★★★★★ 4
No complaints after use
Color: Black/Yellow Accent
Always been a fan of Ironman watches especially the original. The negative display threw me off for a few days but getting used to it. Love the fit and size of it. Not to mention it's extremely light and you barely notice it after a bit. For under $40 if it malfunctions in a year or two I'll just buy another or one similar.
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Reviewed in the United States on November 4, 2025
★★★★★ 5
Bang for the buck
Color: Blackout
Let me previce this review by stating that I have had multiple fitness watches including Garmin suunto Timex and Casio. This watch has some limitations and I will get to them. The first thing is the design and functionality. The picture doesn't do this watch justice. It is sleek. Small enough to not be gaudy. But large enough to look appropriate regardless of your body size. I am 6' 180 lbs and its perfect. The functionality is great. Some watches require a college degree but this watch is simple to program and switch through modes. It has a lap counter countdown timer stop watch as well as time day date etc. It also has more features that don't interest me for fitness so I won't go into them. One complaint other reviewers have stated is with the black background it can be difficult to see display. To them I would reply the top right button is a light. Push it once to illuminate the display. Problem solved. Having a black background does make the display less visible. That's obvious to me but perhaps not everyone. With that being said I only have to use the light if I'm in a dark area. In normal room lighting it is easy to see. This watch does not have GPS capabilities which other watches I've had has. Add another zero to the price of this watch and you can have GPS too. I use this watch mainly for indoor fitness inc swimming and running on an indoor track and use my garmin outdoors. This is a great everyday watch and a great price. No issues no complaints.
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Reviewed in the United States on February 28, 2015