Main Harness - Universal MPFI

The Universal MPFI Main Harness (model 558-104) is the backbone of any multi-point fuel injection conversion or engine management retrofit project. Whether you're swapping a carbureted engine to EFI, upgrading an aging fuel system, or building a custom engine bay, this universal harness serves as the foundation for reliable fuel injector control and sensor integration. Designed for flexibility across multiple platforms, it eliminates the need for custom wiring fabrication and reduces installation time on complex engine management systems.

This harness features a comprehensive wiring layout engineered to manage multiple fuel injectors, oxygen sensors, and related engine management inputs simultaneously. The design accommodates standard MPFI (Multi-Point Fuel Injection) configurations, allowing seamless integration with aftermarket EFI controllers and factory engine management systems. Robust connectors and shielded signal lines minimize electrical noise and ensure clean voltage delivery to injectors, critical for precise fuel delivery and combustion timing. The 4.2 lb harness is compact enough for tight engine bays while providing sufficient conductor gauge and length distribution for typical V6, V8, and inline engine installations.

Mechanics and engine builders favor this universal harness for LS swaps, EFI retrofit kits, and custom engine bay projects where OEM harnesses don't fit or won't interface with modern fuel management systems. Its universal design accommodates various injector counts and sensor configurations, making it ideal for both street and performance applications. Installation requires routing through the engine bay—the included layout supports standard mounting locations—and integration with your chosen ECU or fuel injection controller. Proper grounding and shielding technique during installation are essential for eliminating spark plug noise and ensuring stable idle quality.