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Description
Holley Terminator X MAX Engine Management Systems 550-926TERMINATOR X MAX MPFI W TRANS & DBW, LS1 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 & DBW, LS1
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 550-926 also has 4L60E or 4L80E Transmission control and Drive-By Wire Throttle Body 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:
- For GM LS1/LS6 engines with 24x crank reluctor with EV1 injectors and 4L60E/4L80E transmissions, and drive-by wire throttle body control.
- 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
- Recommended Pedal part number - 10379038
- Includes: 24x LS Engine Main Harness - EV1 Injector Harness - DBW Throttle Body 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
Specs
| Brand | Holley EFI |
|---|---|
| Crank Reluctor | 24x |
| Emission Code | 3 |
| Ignition Type | GM LS 24x |
| Injector Connector | Jetronic / Minitimer (Bosch) |
| Product Type | Terminator X Max LS MPFI |
| Terminator LS Options | Fuel, Spark, Drive-by-Wire, Transmission |
| Part Number | 550-926 |
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
4.7 ★★★★★
Based on 26 reviews
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Product Reviews
★★★★★ 5
Almost perfect
Style: Screen+Charger
Solid mount. I’ve tried other ones but they don’t sit as nicely as this one. It also has a lot of adjustments to allow for using it any way you need it to so it is very versatile. The magnet strength is really good and holds my phone really well. Sometimes it feels too strong which I guess is a good thing. The charging works well but I wish the cable was a little longer
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on April 21, 2026
★★★★★ 5
Great Phone Mount
Style: Screen+Charger
Works great! It’s been a fantastic upgrade for my car. The installation was quick and seamless, and it fits perfectly with the Tesla interior. The wireless charging stays fast and stable. I highly recommend it.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on May 13, 2026
★★★★★ 4
Almost Perfect But With Workaround it Rocks
Style: Dash+Screen+Qi2 Charger, Style: Dash+Screen+Qi2 Charger
This works almost perfectly in my Tesla, with one small tweak for hot summer conditions. It holds my phone very well overall—I position it slightly off-center at about the 10 o’clock position. However, with a larger phone like the Galaxy S25 Ultra, the combination of weight and summer heat can cause the mount to slowly rotate as the suction cup loses some grip.
I found a simple fix that works extremely well: applying a small amount of rosin (the same kind used for violin bows) to the friction point where the rotating arm meets the suction base. That added grip completely solved the issue. Now the mount stays exactly where I position it, even in the heat.
Solid product, and with that minor adjustment, it performs exactly how I need it to.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on May 3, 2026
★★★★★ 5
Great product.
Style: Holder+Dash+Vent+Windshield
This worked perfectly in my vehicle making hands free driving easy. Installation was very simple, easy to charge my phone in this mount. Very stable, my phone never fell out or off.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on April 25, 2026
★★★★★ 5
Almost perfect
Style: Screen+Charger
Solid mount. I’ve tried other ones but they don’t sit as nicely as this one. It also has a lot of adjustments to allow for using it any way you need it to so it is very versatile. The magnet strength is really good and holds my phone really well. Sometimes it feels too strong which I guess is a good thing. The charging works well but I wish the cable was a little longer
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on April 9, 2026