Abstract: An evaporative emissions (EVAP) control system for a vehicle includes a purge pump configured to pump fuel vapor to an engine of the vehicle via a vapor line and a purge valve. The system includes a hydrocarbon (HC) sensor disposed in the vapor line and configured to measure an amount of HC in the fuel vapor pumped by the purge pump to the engine via the vapor line. A controller is configured to: detect an imminent cold start of the engine and, in response to the detecting, perform the cold start of the engine by controlling at least one of the purge pump and the purge valve, based on the measured amount of HC, to deliver a desired amount of fuel vapor to the engine, which decreases HC emissions by the engine.

Abstract: A diagnostic method and system includes a control valve configured to control an amount of air drawn into an evaporative emissions (EVAP) system through an air filter and a vapor canister, and a pressure sensor configured to measure pressure in the EVAP system. The system also includes a controller configured to detect an engine idle-to-off transition and, in response to detecting the engine idle-to-off transition: receive a first pressure from the pressure sensor, fully open a purge valve connected between the vapor canister and an intake port of an engine, fully close the control valve, monitor one or more second pressures received from the pressure sensor, and detect a malfunction of the EVAP system based on the first pressure, at least one of the one or more second pressures, and a diagnostic threshold.

Abstract: An evaporative emissions (EVAP) control system for a vehicle includes a purge pump configured to pump fuel vapor trapped in a vapor canister to an engine of the vehicle via a vapor line when engine vacuum is less than an appropriate level for delivering fuel vapor to the engine, the fuel vapor resulting from evaporation of a liquid fuel stored in a fuel tank of the engine. The EVAP control system includes a hydrocarbon (HC) sensor disposed in the vapor line and configured to measure an amount of HC in the fuel vapor pumped by the purge pump to the engine via the vapor line. The EVAP control system also includes a controller configured to, based on the measured amount of MC, control at least one of the purge pump and a purge valve to deliver a desired amount of fuel vapor to the engine.

Abstract: An evaporative emissions (EVAP) control system for a vehicle includes a purge pump configured to pump fuel vapor to an engine of the vehicle via a vapor line and a purge valve. The system includes a hydrocarbon (HC) sensor disposed in the vapor line and configured to measure an amount of HC in the fuel vapor pumped by the purge pump to the engine via the vapor line. A controller is configured to: detect an imminent cold start of the engine and, in response to the detecting, perform the cold start of the engine by controlling at least one of the purge pump and the purge valve, based on the measured amount of HC, to deliver a desired amount of fuel vapor to the engine, which decreases HC emissions by the engine.

Abstract: An evaporative emissions (EVAP) control system for a vehicle includes a purge pump configured to pump fuel vapor trapped in a vapor canister to an engine of the vehicle via a vapor line when engine vacuum is less than an appropriate level for delivering fuel vapor to the engine, the fuel vapor resulting from evaporation of a liquid fuel stored in a fuel tank of the engine. The EVAP control system includes a hydrocarbon (HC) sensor disposed in the vapor line and configured to measure an amount of HC in the fuel vapor pumped by the purge pump to the engine via the vapor line. The EVAP control system also includes a controller configured to, based on the measured amount of HC, control at least one of the purge pump and a purge valve to deliver a desired amount of fuel vapor to the engine.

Abstract: A diagnostic method and system includes a control valve configured to control an amount of air drawn into an evaporative emissions (EVAP) system through an air filter and a vapor canister, and a pressure sensor configured to measure pressure in the EVAP system. The system also includes a controller configured to detect an engine idle-to-off transition and, in response to detecting the engine idle-to-off transition: receive a first pressure from the pressure sensor, fully open a purge valve connected between the vapor canister and an intake port of an engine, fully close the control valve, monitor one or more second pressures received from the pressure sensor, and detect a malfunction of the EVAP system based on the first pressure, at least one of the one or more second pressures, and a diagnostic threshold.

Abstract: A boost purge ejector tee arrangement for a fuel vapor emissions system can include a boost purge ejector tee having a body that can define a first inlet port, a second inlet port and an outlet port. The first inlet port and the outlet port can be fluidly coupled along a first flow path. The body can define a second flow path from the second inlet port that can intersect the first flow path upstream of the outlet port. A nozzle can be positioned in the first flow path such that an outlet of the nozzle can be proximate the intersection of the second flow path with the first flow path. The boost purge ejector tee can be integrated into an air box that can be associated with an engine such that the outlet port exits into an inside of the air box.

Abstract: A boost purge ejector tee arrangement for a fuel vapor emissions system can include a boost purge ejector tee having a body that can define a first inlet port, a second inlet port and an outlet port. The first inlet port and the outlet port can be fluidly coupled along a first flow path. The body can define a second flow path from the second inlet port that can intersect the first flow path upstream of the outlet port. A nozzle can be positioned in the first flow path such that an outlet of the nozzle can be proximate the intersection of the second flow path with the first flow path. The boost purge ejector tee can be integrated into an air box that can be associated with an engine such that the outlet port exits into an inside of the air box.

Abstract: A loose or missing fuel cap detection method for an evaporative emission control system of an automotive vehicle detects a loose or missing fuel cap based in part on whether fuel level changed. The method determines whether the fuel level changed, which is indicative of a refueling event. The method then determines if one or more leaks are present. If the fuel level changed and one or more leaks are present, the method determines that the fuel cap is loose or missing.

Abstract: A diagnostic method for an evaporative emission control system of an automotive vehicle determines functionality of one of a purge valve and/or a vacuum switch and valve assembly. The vacuum switch and valve assembly is located between a carbon canister and atmosphere and is either open or closed according to whether the system is in a high or low negative pressure condition. A controller determines if the vacuum switch and valve assembly is functioning properly according to the high or low negative pressure condition. The controller determines if the purge valve is functioning properly based on engine performance characteristics.

Abstract: A method is provided for detecting a small or gross leak in an evaporative emission control system of an automotive vehicle. The method includes initially purging and then sealing the evaporative emission control system. A vacuum switch coupled to the evaporative emission control system is then monitored for an opening event caused by a loss of a natural vacuum created in the evaporative emission control system. If said opening event is detected, the method determines if a leak check timer has exceeded a first or second predetermined threshold value. If the leak check timer has not exceeded said first predetermined threshold value a first fault code is set indicating that the gross leak has been detected. If the leak check timer has not exceeded the second predetermined threshold value, a second fault code is set indicating that the small leak has been detected. The first threshold value corresponds to an amount of time required for a leak to be detected having a diameter of about 0.070 inches or greater.

Abstract: A method is provided for cleansing a seal of a device used for sealing an evaporative emission control system of an automotive vehicle. The method starts by determining if a request to close the device has been made. If the request to close the device has been made, the method cycles the device a plurality of times to press and lift the seal off of a seat repeatedly. The method also determines if the seal is closed after the cycling step. If the seal is not closed after the cycling step, the method closes the seal. Preferably, the cycling step includes cycling the device at a pre-selected duty cycle, frequency and cycle count. The duty cycle, frequency, and cycle count correspond to calibration tables prepared for the particular device employed to insure that the seal strikes its seat about three times before sealing.

Abstract: A method is provided for determining the rationality of a device for monitoring the pressure within an evaporative emission control system of an automotive vehicle. The method includes opening a valve of the evaporative emission control system and determining if a vacuum switch of the evaporative emission control system opened. If the vacuum switch opened, a code is set indicating that the vacuum switch passed an opening test. If the vacuum switch did not open, the method determines if a fail timer is greater than a first fail threshold value. The first fail threshold value corresponds to an amount of time within which a properly functioning vacuum switch should open after said valve is opened. If the fail timer is greater than the fail threshold value, the method sets a code indicating that the vacuum switch failed the opening test. If the fail timer is less than or equal to the first fail threshold value, the method increments the fail timer.

Abstract: A method is provided for detecting a small or gross leak in an evaporative emission control system of an automotive vehicle. The method includes initially purging and then sealing the evaporative emission control system. A vacuum switch coupled to the evaporative emission control system is then monitored for an opening event caused by a loss of a natural vacuum created in the evaporative emission control system. If said opening event is detected, the method determines if a leak check timer has exceeded a first or second predetermined threshold value. If the leak check timer has not exceeded said first predetermined threshold value a first fault code is set indicating that the small leak has been detected. If the leak check timer has not exceeded the second predetermined threshold value, a second fault code is set indicating that the small gross leak has been detected. The first threshold value corresponds to an amount of time required for a leak to be detected having a diameter of about 0.

Abstract: A method is provided for detecting a very small leak in an evaporative emission control system of an automotive vehicle. The method includes sealing the evaporative emission control system at a key-off event and monitoring a vacuum switch coupled to the evaporative emission control system for a closing event due to a natural vacuum created in the evaporative emission control system as it cools. If the closing event is not detected, the method determines if a leak detection timer has exceeded a predetermined threshold value. If the timer has exceeded the predetermined threshold value, the method sets a fault code indicating that the very small leak has been detected.

Abstract: A method for controlling fuel vapor purge flow in an automotive type internal combustion engine. The method includes the steps of determining existence of a purge ON condition and determining a simulated engine airflow value. A desired purge flow is calculated as is a value for a desired purge solenoid current. Utilizing a PID control methodology, the desired purge solenoid current is produced and a purge driver generates a PWM signal with to control a purge solenoid with the purge solenoid.

Abstract: A method is provided for testing an evaporative emission control system for a missing or loose fuel cap comprising detecting a refueling event and running a leak detection test of the evaporative emission control system to determine if a large leak is present. If a large leak is detected, the methodology sets a fault code and activates a driver warning lamp indicating a potential cap sealing problem. The leak detection test is repeatedly re-executed after the large leak is detected to determine when the large leak condition ceases. When the large leak condition ceases, the previously set fault code is removed and the driver warning lamp is deactivated. If the large leak does not cease and is detected again after the next refueling event when an opportunity for resealing the cap existed, a new fault code is set indicating that the potential cap sealing problem is a persistent problem so that the integrity of the evaporative system may need to be tested.

Abstract: A method of controlling a proportional purge solenoid is provided to improve low flow resolution. The method includes looking-up a primary duty cycle corresponding to purge current in a three-dimensional surface by using purge flow and vacuum level as inputs. Should the primary duty cycle fall below a lowest allowable purge current threshold value, a secondary purge duty cycle (i.e., an on/off pattern of the primary duty cycle) is obtained from a two-dimensional table by using the actual calculated purge flow as an input. The two-dimensional table includes a sequence of program loops subdivided into a delay region wherein the purge flow and vacuum level data are learned, an updating region wherein the purge current of the three-dimensional surface is updated, and a control region wherein the primary duty cycle is toggled between on and off states. When the current program loop falls within the delay region, a recorded primary duty cycle is output.

Abstract: A method of leak detection for an evaporative emission control system during periods of low engine vacuum includes the steps of pulsing a leak detection pump at a predetermined rate and determining whether engine vacuum level is low. The method also includes the steps of maintaining pressurization of the evaporative emission control system if the engine vacuum level is low, maintaining pressurization behind a vapor canister vent valve if the engine vacuum level is low, and detecting for leaks in the evaporative emission control system after a normal engine vacuum level is attained.

Abstract: A method of de-pressurizing an evaporative emission control system includes the steps of pulsing a leak detection pump at a predetermined rate and purging accumulated vapors from a vapor canister. The method also includes the steps of determining whether a last pump period is greater than or equal to a predetermined system de-pressurization mode pump period and continuing the method if the last pump period is less than the system de-pressurization mode pump period.