US Patent 8463528 Systems and methods for using secondary fuels

The present application provides a system and method for determining a secondary fuel amount for an engine. The method comprises measuring an injector signal from an engine's Engine Control Unit (ECU) for a primary injector. A delay time of the primary injector can be determined using a lookup table. An open time can be calculated based on the delay time and the primary timing value. An amount of fuel to be injected into the engine can be calculated based on the primary injector open time. An amount of secondary fuel equivalent to the amount of primary fuel can be determined. A timing value for a secondary injector signal for the secondary injector can be calculated to deliver the amount of secondary fuel to the engine.