An embodiment is a method including controlling a purge fuel amount of an active purge system (APS), the controlling including correcting the purge fuel amount using a primary weighting factor obtained using an ambient air temperature and a hydrocarbon (HC) concentration in purge gas fuel as input values, and correcting the corrected purge fuel amount using a secondary weighting factor due to a purge learning value. Some embodiments further include controlling of the purge fuel amount applies a purge execution condition, and the purge execution condition on the basis of a negative pressure of an intake manifold and a vehicle speed of the vehicle in which a purge flow rate exhibits as being greater than or equal to a predetermined value.

Evaporative emission purge control systems and methods use a cost factor to incentivize operation of an internal combustion at torques favorable for purge. An evaporative emission control system is configured to collect fuel vapor. A controller determines whether an operating speed of the internal combustion engine is within a target purge region that is bounded by a lower speed threshold and an upper speed threshold of the internal combustion engine. When the operating speed of the internal combustion engine is within the target purge region, the controller applies a cost factor to operating points for the internal combustion engine, and based on the cost factor, the operating points are set to include an operating torque for the internal combustion engine to generate an intake pressure of the internal combustion engine at a level below atmospheric pressure for a purge of the evaporative emission control system.

A leakage diagnostic device diagnoses leakage of evaporated fuel in an evaporative fuel treatment device. The evaporative fuel treatment device purges evaporated fuel, which is generated in a fuel tank and adsorbed on a canister, to an intake passage. The leakage diagnostic device includes a vent valve that blocks a first atmospheric passage, which connects the canister with an atmospheric opening, and a pump that pressurizes and depressurizes a second atmospheric passage, which is a bypass passage of the first atmospheric passage. The malfunction diagnostic device diagnoses malfunction of the leakage diagnostic device based on an output value of a pressure sensor that detects pressure in a passage connected to the canister.

Methods and systems are provided for reducing a possibility of hydrocarbon (HC) release to atmosphere from an evaporative emissions control (EVAP) system. In one example, a method may include, isolating a fuel vapor canister of the EVAP system from atmosphere and an engine intake manifold upon conditions being met for a potential hydrocarbon (HC) breakthrough from the fuel vapor canister.

Methods and systems are provided for reverse purging of a fuel vapor canister of an engine. In one example, a method may include heating a fuel vapor canister, sealing a fuel tank in order to generate a vacuum in the fuel tank, and in response to the pressure in the fuel tank reaching a target vacuum, initiating reverse purging of the fuel vapor canister.

Vehicle fuel fill control systems may anticipate vehicle refueling events in order to control the timing of fuel tank depressurization sequences. In a first embodiment, a global positioning system (GPS) is utilized to anticipate the vehicle refueling event prior to initializing the depressurization sequence. In another embodiment, a camera system is utilized to anticipate the refueling event prior to initializing the depressurization sequence. In yet another embodiment, both the GPS and the camera system may be utilized to anticipate the refueling event. By anticipating refueling events, customer wait time for gaining refueling access may be reduced.

Methods and systems for diagnosing operation of an evaporative emissions system are described. The methods and systems may include increasing an amount of vacuum stored in an evaporative emissions system during discontinuously operating an engine in a boosted operating mode. Storing vacuum allows the evaporative emissions system to reach a desired vacuum level to verify absence of an evaporative emissions system breech.

Methods and systems are provided for an ultrasonic wave generator within a vehicle emissions control system. In one example, a frequency of ultrasonic waves may be applied to a fuel vapor canister, the frequency adjusted in response to an estimate of hydrocarbon distribution within a vapor canister received from temperature and hydrocarbon sensor outputs.

Methods and systems for diagnosing operation of an evaporative emissions system are described. The methods and systems may include increasing an amount of vacuum stored in an evaporative emissions system during discontinuously operating an engine in a boosted operating mode. Storing vacuum allows the evaporative emissions system to reach a desired vacuum level to verify absence of an evaporative emissions system breech.

Methods and systems are provided for indicating a restriction in a fuel system vapor recovery line. Responsive to such an indication, methods and systems are provided for taking mitigating actions such that an entirety of a vehicle fuel system and evaporative emissions system, including a fuel filler system, may be diagnosed as to a presence or absence of undesired evaporative emissions, even with the restriction in the vapor recovery line present. In this way, undesired evaporative emissions may be reduced or avoided, completion rates for such tests may be increased, and customer satisfaction may be improved.