HP ECU & Harness MPFI - NTK

The Holley HP ECU & Harness MPFI - NTK (model 550-604N) is a complete engine control module and wiring harness system designed for V8 multi-port fuel injection applications. This kit integrates Holley's proven high-performance EFI electronics with an NTK oxygen sensor, delivering precise fuel metering and ignition control for naturally aspirated and forced-induction V8 engines. Operators and engine builders rely on this system to achieve repeatable, optimized combustion management in street, track, and off-road applications where fuel delivery accuracy directly impacts power output and drivability.

The complete harness assembly integrates the ECU, sensor inputs, fuel injector outputs, and ignition control into a single loom, minimizing installation labor and reducing wiring errors common in standalone EFI conversions. The included NTK oxygen sensor provides closed-loop feedback for stoichiometric fuel control across varying engine loads and speeds. This HP variant supports advanced tuning parameters—timing curves, fuel maps, and boost control—essential for modified engines that demand more than factory calibrations provide. The modular design accommodates both carbureted-to-EFI conversions and factory engine swaps without requiring extensive custom fabrication.

This system is built for engine builders, restoration shops, and serious enthusiasts converting older V8 platforms to fuel injection or upgrading existing EFI systems with tunable performance electronics. It addresses the primary challenge of standalone EFI integration—reliable sensor communication, accurate fuel delivery sequencing, and seamless ignition timing across the full RPM and load envelope. Whether supporting a 5.0L small-block rebuild, a big-block restomod, or a forced-induction platform, the Holley HP ECU 550-604N provides the control architecture to maximize power while maintaining driveability and cold-start reliability.