Patent ID: 6401528
Filing Date: 2002-06-11
Classification: F02D,F02M

Abstract:
A method of determining cumulative evaporative emissions of hydrocarbons from a vehicle during a test period, said vehicle having an engine that is operated under a microprocessor-based engine controller, a fuel evaporation emission control system comprising a fuel tank for hydrocarbon fuel and fuel vapor adsorption means connected to said fuel tank and said engine, and a self-diagnostic system that detects malfunctions in said fuel evaporation emission control system, said method comprising the steps ofmeasuring the temperature at a location within said vehicle at regular, predetermined intervals of time during said test period when the engine is not running and recording said temperatures in a micro-processor readable memory, determining the lowest recorded temperature in a twenty-four hour period of said test as a basis for diurnal or partial diurnal cumulative emission determinations, and determining the cumulative evaporative emissions during said test period as a function of the cumulative effect of said diurnal and/or partial diurnal temperatures.