How an Auxiliary Controller Manages Supplemental Fuel Injection

A method for an add-on computer to calculate and control extra fuel injection by piggybacking on data from a car's original engine computer.

What it covers

This patent describes a system where an auxiliary controller intercepts data from a vehicle's factory-installed Engine Control Unit (ECU) to manage a secondary set of fuel injectors. By receiving the primary fuel injector's 'on time' and the total engine air mass, the auxiliary controller calculates exactly how much extra fuel is needed to reach a desired air-to-fuel ratio. It then determines the precise timing for the secondary injectors to fire for each engine cylinder. This allows for precise fuel enrichment without needing to reprogram or replace the original factory computer.

What it doesn't cover

• —Does not cover systems that replace the factory ECU entirely.
• —Does not cover fuel injection systems that operate without receiving air mass data from the primary ECU.
• —Does not cover mechanical fuel injection systems that lack electronic timing control.
• —Does not cover systems that do not calculate individual injector 'on times' based on cylinder-specific air mass data.

The clever bit

The system dynamically calculates the supplemental fuel mass by subtracting the primary fuel contribution from the total required fuel, effectively treating the secondary injectors as a 'trim' system that works in harmony with the factory's existing logic.

Why it matters

This technology is highly relevant for the automotive aftermarket, particularly for performance tuning and alternative fuel conversions (like E85 or methanol). By allowing an auxiliary device to handle supplemental fueling, tuners can increase engine power or switch fuel types without the extreme complexity and cost of hacking or replacing the proprietary factory engine management software.

Real-world examples

• 1.Aftermarket port fuel injection controllers for forced induction engines
• 2.E85 flex-fuel conversion kits
• 3.Nitrous oxide injection fueling controllers
• 4.Water-methanol injection systems with electronic fuel mapping