Gm Global Technolgoy Operations, Inc.

Robert W Jackson

William R Cadman

John F Van Gilder

David Edward Prout

Kurt D McLain

Miles K Maxey

Kenneth J Kalvelage

Paul William Rasmussen

Wenbo Wang

Kurt D Mc Lain

A system includes a diagnostic module that selectively performs a purge valve leak diagnostic to diagnose a leak in a purge valve in a fuel system of a vehicle. Performing the purge valve leak diagnostic includes determining a level of vacuum in a fuel tank. A control module determines at least one operating condition associated with the vehicle. The at least one operating condition corresponds to an operating condition that affects the level of vacuum in the fuel tank. The control module, based on the at least one operating condition, selectively modifies the purge valve leak diagnostic. Selectively modifying the purge valve leak diagnostic includes at least one of preventing the diagnostic module from performing the purge valve leak diagnostic, preventing the diagnostic module from completing the purge valve leak diagnostic, and causing the diagnostic module to indicate that a result of the purge valve leak diagnostic was indeterminate.

Purge valve leak diagnostic robustness improvements for small turbocharged engines

A system includes an ignition detection module, a pressure sensor, a pressure variation module, and a pressure sensor diagnostic module. The ignition detection module detects when an engine is started. The pressure sensor generates a first pressure signal indicating a first pressure within a fuel system of the engine when the engine is started and when a purge valve of the fuel system is closed. The pressure variation module determines an amount of variation in the first pressure signal over a first period. The pressure sensor diagnostic module determines a state of the pressure sensor based on the amount of variation in the first pressure signal over the first period.

System and method to diagnose fuel system pressure sensor

A system according to the principles of the present disclosure includes a pressure sensor, a pressure variation module, and a purge flow diagnostic module. The pressure sensor generates a pressure signal indicating a pressure within a fuel system of an engine. The pressure variation module determines an amount of variation in the pressure signal over a period. The purge flow diagnostic module diagnoses a fault associated with flow through a purge valve of the fuel system when the pressure variation amount is less than a threshold.

System and method for diagnosing flow through a purge valve based on a fuel system pressure sensor

A control system according to the principles of the present disclosure includes a fuel system diagnostic module and a pump control module. The fuel system diagnostic module performs a diagnostic test on a fuel system when a vacuum pump is switched off to prevent flow through the vacuum pump and thereby seal a portion of the fuel system from an atmosphere. The vacuum pump includes a cam ring, a rotor that rotates within the cam ring, and vanes that slide into and out of slots in the rotor as the rotor rotates. The pump control module switches on the vacuum pump for a predetermined period to force the vanes out of the slots and into contact with the cam ring to seal the vacuum pump before switching off the vacuum pump for the fuel system diagnostic test.

System and method for controlling a vacuum pump that is used to check for leaks in an evaporative emissions system

A system for a vehicle includes a first pressure module and a blockage indication module. The first pressure module receives a signal from a pressure sensor that measures pressure within a fuel vapor purge system. The first pressure module generates a first pressure based on the signal at a first time and generates a second pressure based on the signal at a second time. The second time is after the first time. The blockage indication module indicates whether a blockage is present in the fuel vapor purge system between the pressure sensor and a fuel tank based on a difference between the first and second pressures.

Fuel system blockage detection and blockage location identification systems and methods

A vehicle includes an engine, a sealed fuel system having a fuel tank, a canister for storing fuel vapor, a vapor circuit external to the fuel tank, and a control valve. The vapor circuit includes an absolute pressure sensor and a switching valve connecting the fuel tank to the control valve. A controller evaluates or diagnoses a vapor purge function of the sealed fuel system using vacuum measurements from the absolute pressure sensor, executing or diagnosing only when the engine is running, purge is enabled, and the pump is off. The controller diagnoses the vapor purge function by comparing the vacuum measurements to a threshold vacuum. An apparatus includes the vapor circuit and controller. A method for diagnosing the vapor purge function includes actuating the switching valve, measuring a vacuum in the system using the absolute pressure sensor, and comparing the measured vacuum to a threshold vacuum.

Low purge flow vehicle diagnostic tool

A fuel system diagnostic wakeup system for a vehicle includes a first control module. The first control module generates a wakeup request, powers off when the vehicle powers off, and powers on and performs a fuel system diagnostic in response to a wakeup signal while the vehicle is powered off. A second control module independent of the first control module receives the wakeup request and generates the wakeup signal after the vehicle powers off based on the wakeup request.

Method and apparatus for engine control module wake-up test

A vehicle includes a sealed fuel system and a controller. The fuel system includes a fuel tank, a fuel cap, a control orifice, and an absolute pressure sensor. The controller associates a threshold large leak in the fuel system with a fuel cap sealing error. The controller detects completion of a prior refueling event, compares measurements from the pressure sensor to a reference vacuum across the control orifice to determine the presence of the threshold large leak, and sets a diagnostic code corresponding to the large leak only upon completion of the prior refueling event. A method for detecting the large leak includes detecting completion of the refueling event, comparing vacuum measurements from the absolute pressure sensor to a reference vacuum across the orifice to determine the presence of the large leak, and setting a diagnostic code corresponding to the large leak only upon completion of the prior refueling event.

Large leak diagnostic tool for a sealed fuel system in a vehicle

A control module and method for operating the same includes a diurnal control valve module that opens a diurnal control valve (DCV) and an evaporative leak check module (ELCM) diverter valve control module that switches on an ELCM diverter valve. The control module includes a correlation module performs a correlation of a ELCM pressure signal and a fuel tank pressure signal and that generates a fault signal in response to the correlation when the DCV valve is open and the ELCM diverter valve is on.

Method and system for correlating a pressure sensor for a fuel system

A restriction diagnostic system for a vehicle comprises a pressure difference module and a diagnostic module. The pressure difference module determines a pressure difference between an ambient air pressure and a filtered air pressure measured at a location between an air filter and a valve that is selectively opened to enable ambient airflow through the air filter to a fuel vapor canister. The diagnostic module selectively diagnoses restriction of the airflow through the air filter when the pressure difference is greater than a predetermined pressure.

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Brighton, MI, United States of America

Robert W Jackson