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Holley 550-903 - Holley 550-903 TERMINATOR X Engine Management System
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HOLLEY TERMINATOR X 550-903
Works with LS1 and LS6 engines with a 24x crank trigger, 1x cam, 1bar MAP sensor, and EV1 injector harness. Includes a 3.5 inch touchscreen display. Cannot program through EFI Standalone Digital Dash Kits. This kit does not operate variable valve timing (VVT) or displacement on demand (DOD) systems.
The Holley Terminator X engine management systems let you take control of your domestic V8 engine. These kits give you complete charge of your engine and self-learning fuel strategies, along with the proven, race-winning technology of Holley EFI—all at a budget-friendly price! Every MPFI Terminator X features real-time fuel learn, high impedance injector drivers, an integrated one-bar MAP sensor—and four programmable inputs and outputs, ideal for electric fans, boost control solenoids, progressive nitrous control, and much more. All systems come fully loaded with base maps for common engine combinations to get you out of the garage and onto the road or track fast.
Features include:
* Holley EFI industry-leading, easy-to-use software suite allows full laptop access for advanced users
* Real-time fuel map learn—takes the guesswork out of tuning your base fuel table
* High-impedance injector drivers will safely power most standard injectors and Holley EFI injectors. (Will not control low-impedance injectors)
* Bosch LSU 4.9 wideband relays AFR information to the ECU for accurate reading and precise tuning control
* On-board one-bar MAP sensor is perfect for N/A or nitrous engine combos
* MAP sensor vacuum hose adapters
* 4 inputs: 12 V, ground, 5 V, and frequency
* 4 outputs: Ground, PWM for accessories
* Boost control: boost vs. time, boost vs. gear, boost vs. rpm, boost vs. speed, and boost safeties
* Nitrous control: single channel of wet or dry, progressive or non-progressive, rich/lean safeties, and target closed loop AFR; adjustable through touch screen
* Advanced tables: 4 x 1D tables, 1 x 1D per gear table, 4 x 2D tables, 1 x 2D per gear table
* On-board diagnostic LEDs allow you to identify any critical engine issues at a glance
* 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
* Available with or without a 3.5 in. touch screen LCD hand-held with easy-to-use calibration wizard; allows you to quickly build a base tune for most domestic V8 engines, as well as tuning and gauge display functions (not available with every kit)
Let customers speak for us
from 269 reviews
Set of 3 hood vents installed on my 03 Z06, great product, fits great and pulls out the heat 🥵

Fast shipping great customer service

Brian at FI Performance always goes above and beyond to take care of customers. I am a repeat customer and will continue to use them for all my needs. Thanks again Brian, amazing as always!

Exactly what I needed for my lowered C5. Full range of adjustment and quality made product.

Got a great product. In a very timely manner very happy

Great experience, order got messed up and Brian made sure to get it fixed and kept me up to date by texting me.

Exactly what I needed and had it next day

Customer service was great. Order shipped quick. Great value and the change to the car was better than expected. Wife no longer braces herself for the expansion joints and other Ohio road issues.

Brian was AWESOME to deal with, I changed my mind a few times on what I wanted to do with my c6z.. You can go down an endless rabbit hole when you get into these cars “while I’m in there “He was right there with updating pricing and I couldn’t ask for more.. Parts are parts and they will fail but it’s the service that sets the bar for a big purchase.. I haven’t driven the setup yet as it’s still being built but I’m sure he a phone call away to get it sorted..

Great customer service as always. Was on my doorstep within 48 hrs.

High quality parts with installation pics to come

Great support team helped me get the parts needed and got my order within the week.

Balancer was exactly what I needed. Everything as described and fast shipping. Thanks guys

Team went above and beyond to locate the part needed to get my can back on the road asap.

I finally got to install the intake which literally took 10 minutes. The power and launch difference was insane! You can hear the turbos spooling a lot better as well. I’m amazed by the difference just from the intake