Patent ID: 8560167
Filing Date: 2013-10-15
Classification: G01M

Abstract:
1. A vehicle comprising: a fuel system having a fuel tank and a canister; a diagnostic module having a reference orifice, a pressure sensor, a change-over valve (COV), and a pump, the module connecting the fuel system to atmosphere to selectively provide: (i) a first configuration having the COV in a first position fluidly connecting the canister and atmosphere with the pump and orifice inoperable, (ii) a second configuration with the COV in the first position and the orifice fluidly connecting the canister and atmosphere with the pump operable, and (iii) a third configuration with the COV in a second position and the orifice fluidly connecting the canister and atmosphere with the pump operable, wherein the orifice provides an independent flow path from the canister to atmosphere compared to the COV when the module is in the second and third configurations; and a controller configured to: (i) measure a reference pressure across the orifice to provide a dynamically established threshold; (ii) isolate the fuel system in a low pressure state; (iii) measure a series of pressures in the system; and (iv) provide a code in response to comparing the series to the dynamically established threshold.