A control system for a vehicle includes a controller. The controller is configured to receive signals from a plurality of vehicle sensors, a vehicle communications system, a ride-share application, a navigation system, or a combination of these. The controller is configured to determine whether at least one of a plurality of conditions is met to execute a small leak test on a fuel system of the vehicle based on the signals, where the plurality of conditions include an available time segment to execute the small leak test, a level surface, a smooth surface, and a constant vehicular momentum. The controller is configured to execute the small leak test when at least one of the plurality of conditions is met.

An evaporated fuel treatment apparatus includes an abnormality determination unit that determines an abnormality of a purge passage. The abnormality determination unit changes an operating cycle of a purge control valve to a cycle longer than an initial set value while maintaining a duty ratio of the purge control valve set according to an operating state of an internal combustion engine, and determines an abnormality of the purge passage based on a first variation range and a second variation range calculated from a detection value detected by an airflow meter before and after the change of the operating cycle.

Various embodiments include a method for operating a fuel evaporation retention system of a vehicle with an internal combustion engine. It includes measuring a pressure change resulting from a temperature change of a gas volume in the fuel tank over a defined period of time while the vehicle is at a standstill after the engine controller has been switched off and comparing an expected pressure profile based on a given temperature profile based at least in part on the tank fill level and after the engine controller has been switched on to an actual measured pressure profile from a previous vehicle standstill phase. If the measured pressure profile lies within a settable tolerance around the expected pressure profile, the method confirms a leak-tight fuel tank. If the measured pressure profile lies outside the settable tolerance, the method identifies a faulty fuel tank and displaying an alert.

An active dual purge system includes: an intake pipe, a compressor to compress air, a canister to collect an evaporation gas, a purge line extending from the canister to a front end of the compressor, a branch line branching off from the purge line and extending to a rear end of a throttle valve body, a purge pump installed in the purge line, a purge valve installed in the purge line, a vent valve installed in a vent line extending from the canister toward the atmosphere, a first sensor installed in the purge line, and a second sensor installed in the purge line, and a controller to perform different tests on the purge pump, the purge valve and the vent valve in different operating states, and diagnose whether at least one of the purge line, the branch line, or the vent line are abnormal using on-board diagnosis (OBD).

A system and method for leak check module including first and second solenoid valves. A first solenoid valve is configured to be coupled between a fuel vapor canister and atmospheric air for controlling air flow in a first flow path between the fuel vapor canister and atmospheric air. A pump is configured to be coupled to atmospheric air. A second solenoid valve is configured to be coupled between the pump and the fuel vapor canister for controlling air flow in a second flow path between the fuel vapor canister and atmospheric air through the pump.

A first arrival flow rate that is a flow rate of evaporative fuel gas that has arrived in a throttle downstream portion located downstream of a throttle valve in an intake pipe via a second purge passage after passing through a purge control valve is estimated based on a valve passage flow rate that is a flow rate of evaporative fuel gas that has passed through the purge control valve, and a first response delay in the flow of evaporative fuel gas through a route extending from the purge control valve to the throttle downstream portion via the second purge passage.

A method for increasing a purge rate of fuel evaporation gas of a vehicle may include: determining, by a controller, a first fuel evaporation gas density in a purge pump included in an active fuel evaporation gas purge system of the vehicle; filtering the first fuel evaporation gas density using a filter for controlling an amount of change in the first fuel evaporation gas density; determining a second fuel evaporation gas density in the purge pump based on the filtered first fuel evaporation gas density; determining a third fuel evaporation gas density in a standard temperature and pressure state; determining a concentration of hydrocarbon within the fuel evaporation gas based on the third fuel evaporation gas density; and increasing the purge rate of the fuel evaporation gas based on the hydrocarbon concentration in the fuel evaporation gas.

A failure diagnosis method and a failure diagnosis system of a dual purge system may determine whether a closed stuck failure or an opened stuck failure occurs in a line forming a dual purge system by measuring a pressure in a negative pressure formation device and comparing the corresponding pressure with a predetermined reference value when a purge valve of the dual purge system is in an opened or closed state, and may determine whether the failure occurs in components related to a secondary purge line in the dual purge system in which it is difficult to determine whether the failure occurs in a conventional failure diagnosis method of a single purge system in a simple method.

Methods and systems for determining pressure changes across at least two fuel vapor storage canisters are described. The methods and systems may include determining the pressure changes via a sole pressure sensor. In one example, fuel vapor canister bypass passages are provided to determine pressure values at a plurality of positions within an evaporative emissions system.

Various embodiments include a method for operating a fuel evaporation retention system of a vehicle with an internal combustion engine. It includes measuring a pressure change resulting from a temperature change of a gas volume in the fuel tank over a defined period of time while the vehicle is at a standstill after the engine controller has been switched off and comparing an expected pressure profile based on a given temperature profile based at least in part on the tank fill level and after the engine controller has been switched on to an actual measured pressure profile from a previous vehicle standstill phase. If the measured pressure profile lies within a settable tolerance around the expected pressure profile, the method confirms a leak-tight fuel tank. If the measured pressure profile lies outside the settable tolerance, the method identifies a faulty fuel tank and displaying an alert.