Holley EFI Terminator X Max Gen III HEMI EFI System

2003–2006 Chrysler 5.7L / 6.1L / 6.4L GEN III HEMI Engines

550-1421

Overview:

The Holley EFI Terminator X Max Gen III HEMI EFI System is a comprehensive engine management solution designed specifically for Chrysler GEN III HEMI engines from 2003 to 2006, including the 5.7L, 6.1L, and 6.4L variants equipped with the factory Drive-by-Wire throttle body (non-VVT). This advanced EFI system delivers precise fuel and ignition control, real-time fuel learning, and extensive tuning capabilities, making it ideal for enthusiasts seeking reliable, high-performance engine management without the complexity of traditional carburetion.

Whether you are upgrading a street-driven muscle car or building a track-ready race machine, the Terminator X Max offers a plug-and-play solution that simplifies installation and accelerates your tuning process. Its intuitive 3.5" touchscreen handheld and included Holley EFI software provide both beginner-friendly calibration wizards and advanced laptop tuning options, ensuring you have full control over your engine’s performance.

Key Features:

Designed to maximize the potential of your GEN III HEMI, the Terminator X Max includes a host of features engineered for flexibility, precision, and ease of use:

• Plug-and-play compatibility with 2003–2006 Chrysler 5.7L, 6.1L, and 6.4L GEN III HEMI engines using factory Drive-by-Wire throttle bodies (non-VVT only)
• High impedance injector drivers supporting Holley EFI and most stock injectors (does not support low impedance injectors)
• Integrated Bosch LSU 4.9 wideband O2 sensors for accurate air/fuel ratio monitoring and closed-loop tuning
• Built-in 1 bar MAP sensor with option to disable for external MAP sensor use on boosted applications
• Four programmable inputs and outputs for electric fans, boost control solenoids, nitrous activation, and more
• Advanced boost control options including boost vs. time, gear, RPM, and speed with built-in safeties
• Comprehensive nitrous control channels supporting wet/dry, progressive/non-progressive setups with rich/lean safeties
• Multiple advanced tuning tables including 1D and 2D maps for fuel, spark, and boost management
• Compact ECU design (7.45” x 4.1” x 1.66”) for versatile mounting locations
• 3.5” touchscreen handheld with calibration wizard, data logging, and customizable gauge displays
• Free Holley EFI tuning software for full laptop control and advanced tuning capabilities
• Plug-and-play compatibility with Holley EFI accessories such as gauges, shift lights, and digital/pro dashes (P/N 553-106, 553-111, 553-112)

Construction & Design:

The Terminator X Max ECU is engineered with a compact, rugged enclosure designed to withstand the harsh automotive environment while providing flexible mounting options. The system integrates high-quality Bosch wideband O2 sensors and a reliable 1 bar MAP sensor to ensure precise engine monitoring. The included EV6 injector harness and vacuum hose adapters (1/8”, 1/4”, and 3/16”) facilitate seamless integration with factory components, minimizing installation complexity.

Holley’s focus on user-friendly design is evident in the intuitive touchscreen handheld controller, which offers quick access to tuning parameters, real-time data, and diagnostic LEDs that provide instant feedback on critical engine functions such as ECU power, engine run status, TPS calibration, and cam signal detection.

Installation & Fitment:

The Terminator X Max EFI system is a direct plug-and-play solution for 2003–2006 Chrysler GEN III HEMI engines equipped with factory Drive-by-Wire throttle bodies (non-VVT). Installation requires no major modifications, as the system includes all necessary wiring harnesses and adapters to connect with stock injectors and sensors. The compact ECU can be mounted in a variety of locations, but it is important to orient the diagnostic LEDs facing upward for proper visibility.

For boosted applications, the internal MAP sensor can be disabled to accommodate an external MAP sensor, with a terminated connector included for easy installation. The system’s compatibility with Holley EFI accessories further simplifies integration with existing gauges and control modules.

What's Included:

• Terminator X Max ECU unit
• 3.5” touchscreen handheld controller
• EV6 injector harness
• Bosch LSU 4.9 wideband O2 sensors
• Built-in 1 bar MAP sensor
• Vacuum hose adapters (1/8”, 1/4”, 3/16” sizes)
• Terminated connector for external MAP sensor
• Free Holley EFI tuning software
• Base calibration maps for common GEN III HEMI engine combinations

Ideal For:

The Holley EFI Terminator X Max Gen III HEMI EFI System is perfect for enthusiasts and builders who want a reliable, easy-to-install engine management solution for their 2003–2006 Chrysler 5.7L, 6.1L, or 6.4L HEMI engines. It suits a wide range of applications from budget street builds to boosted race cars, offering advanced tuning features without the complexity or cost of standalone systems. Whether upgrading a classic muscle car or building a modern performance machine, this EFI system delivers precise control and adaptability to meet your needs.

Holley EFI delivers standalone engine management and EFI systems built for everything from engine swaps to serious horsepower builds. With platforms like Sniper, Terminator X, HP, and Dominator, Holley EFI is aimed at enthusiasts who want modern tuning control, data, and drivability—whether it’s a street car, track car, or full-on race program.