Systems and methods for improving vehicle engine stability
AssigneeFord Global Technologies, LLC
InventorAed Dudar
Life of this patent
Estimating the term…
Abstract
Methods and systems are provided for conducting a diagnostic on a fuel tank isolation valve that regulates a flow of fuel vapors from a fuel tank to an evaporative emissions system. In one example, a method comprises determining whether the fuel tank isolation valve is stuck in a first open position or a second open position based on a time duration between commanding open a canister purge valve to direct fuel vapors to an engine, and an exhaust gas sensor indicating a rich air-fuel ratio. In this way, appropriate mitigating action may be taken in response to the fuel tank isolation valve being stuck in either the first open position or the second open position.
Claims20
A method comprising:
- diagnosing whether a fuel tank isolation valve positioned in a load conduit between a fuel system and a fuel vapor storage canister is stuck in a first open position or a second open position based on a time duration between commanding open a canister purge valve to direct fuel vapors to an engine and an exhaust gas sensor indicating a rich air-fuel ratio as compared to a stoichiometric air-fuel ratio.
A method for a vehicle comprising:
- diagnosing whether a fuel tank isolation valve that regulates a flow of fuel vapors from a fuel system to an evaporative emissions system that includes a fuel vapor storage canister is stuck in a first open position or a second open position based on a time duration for an exhaust gas sensor to indicate a rich air-fuel ratio in response to purging the fuel vapors to an engine;
- and
- taking mitigating action in response the fuel tank isolation valve being stuck in the first open position or the second open position.
A system for a vehicle, comprising:
- a fuel tank isolation valve positioned in a load conduit between a fuel tank and a fuel vapor storage canister, the fuel tank isolation valve configurable in a first position, a second position, and a third position, the first position comprising a closed position, the second position comprising a first open position, and the third position comprising a second open position;
- an exhaust gas sensor positioned in an exhaust passage of an engine;
- and
- a controller with computer readable instructions stored on non-transitory memory that when executed cause the controller to:
- responsive to an indication that the fuel tank isolation valve is not adopting the first position when commanded to do so, conducting a diagnostic to determine whether the fuel tank isolation valve is stuck in the first open position or the second open position, the diagnostic based on a time frame in which fuel vapors stemming from the fuel tank are routed to an engine as monitored via output from the exhaust gas sensor.
Dependencies are inferred from the claim text.