Abstract: Systems and methods for operating an engine that includes an exhaust tuning valve in its exhaust system are described. In one example, a position of the exhaust tuning valve may be adjusted to reduce a possibility of the exhaust tuning valve becoming stuck due to freezing water. In particular, the exhaust tuning valve may be cycled as ambient temperature approaches a temperature at which water freezes.

Abstract: Methods and systems are provided for executing a leak test diagnostic of a variable volume fuel tank. In one example, a method includes diagnosing a presence of an absence of a leak in a bellows via actuating a bellows valve fluidly coupling the bellows to a vapor canister during a key-off event.

Abstract: Methods and systems are presented for diagnosing operation of a fuel tank pressure sensor. The methods and systems may include releasing fuel vapors from a fuel tank to an engine when an engine is rotating in a fuel cut out mode while a catalyst temperature is greater than a threshold temperature to determine whether or not the fuel tank pressure sensor is degraded.

Abstract: Methods and systems are provided for an evaporative emission fuel (EVAP) system. In one example, a method for the EVAP system includes loading canisters in parallel sequentially during a refueling event. The method further includes switching loading from one canister to another in response to a fuel level during the refueling event.

Abstract: Methods and systems are provided for routing secondary air to engine an exhaust system during a cold-start condition to reduce tail pipe emissions. In one example, a method may include operating a pump of an evaporative leak check module (ELCM) in a positive pressure mode and routing pressurized air to the exhaust passage upstream of an exhaust catalyst via an air conduit housing a first valve.

Abstract: Methods and systems are provided for an evaporative emission fuel (EVAP) system. In one example, a method for the EVAP system includes adjusting a vapor flow path to a plurality of canisters based on a canister load and a vehicle shut-off event occurring. The method further including flowing vapors to a less loaded canister later than to a more loaded canister.

Abstract: A float assembly of a fluid-level sensor includes a float and an arm assembly. The arm assembly has a first attachment portion connectable to a fluid-level sensor and a second attachment portion connected to the float. The arm assembly further has an articulating joint that permits relative movement between the float and the first attachment portion. A sensor attached to the float.

Abstract: Methods and systems are provided for a fuel system. In one example, a method includes flowing fuel tank vapors to a catalyst during a fuel tank depressurization in response to a refueling request. The method further includes executing an engine vapor flush following a refueling event being completed.

Abstract: 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.

Abstract: 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.

Abstract: Methods and systems are provided for engine braking in a vehicle. In one example, a method may include deactivating fueling to at least one cylinder of an engine, increasing an air mass provided to the engine via an electric boosting device, and adjusting an exhaust valve opening timing of the at least one cylinder in response to a request for engine braking. In this way, an amount of engine braking torque may be increased with reduced wear to engine system components.

Abstract: Methods and systems are provided for controlling a vehicle engine to reduce engine knock and increase fuel efficiency by reducing hydrocarbon breakthrough. In one example, a method may include adjusting a compression ratio of a variable compression engine in response to hydrocarbon breakthrough above a threshold from a fuel vapor canister of an evaporative emissions system.

Abstract: Systems and methods for operating an engine that includes an exhaust system with a differential pressure sensor are described. In one example, output of the differential pressure sensor is compared to output of a barometric pressure sensor to determine whether or not the barometric pressure sensor is degraded. The output of the differential pressure sensor may be monitored while the engine is rotated without being fueled.

Abstract: Methods and systems are provided for diagnosing a heating element coupled to a canister of an evaporative emissions control (EVAP) system. In one example, a method (or system) may include evacuating the canister at different temperature conditions, and diagnosing the heating element based on the different times taken to evacuate the canister at the different temperature conditions.

Abstract: Methods and systems are presented for operating a refueling valve of an evaporative emissions system. The methods and systems may attempt to reactivate a refueling valve that has stuck due to the refueling valve being exposed to liquid fuel. In one example, a voltage that is applied to the refueling valve may be increased to reactivate the refueling valve.

Abstract: A method of controlling an evaporative emissions system for a vehicle is provided. A fuel system for a vehicle and a vehicle are also provided. A signal indicative of an entry condition associated with a secondary air flow path for a purge of an evaporative emissions canister is received. A filter is decoupled from a port of the evaporative emissions canister in response to receiving the signal and prior to the evaporative emissions canister purge. The evaporative emissions canister is purged by flowing atmospheric air into the port and through the evaporative emissions canister while the filter is decoupled from the port. The filter is coupled to the port of the evaporative emissions canister after purging the canister.

Abstract: Systems and methods for operating an engine that includes an exhaust system with a carbonaceous soot trap described. In one example, a carbonaceous soot load estimate for the carbonaceous soot trap is performed when a differential pressure sensor is degraded. The carbonaceous soot estimate may be performed when the engine is not rotating.

Abstract: 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.

Abstract: Methods and systems are provided for performing a reverse purge of an evaporative emissions canister in a vehicle with a sealed variable volume fuel tank. In one example, a method may comprise in response to an ambient temperature reducing during a diurnal temperature cycle, and further in response to the EVAP canister loaded with fuel vapors above a threshold, closing a valve positioned at an atmospheric port of the fuel tank and opening a fuel tank isolation valve. In one example, the fuel tank isolation valve may be in fluid communication between the fuel tank and the EVAP canister. In this way, it is possible to convert a sealed variable volume fuel tank to a vented pressurized fuel tank and initiate a reverse purge during the cooldown hours of the diurnal temperature cycle.

Abstract: Methods and systems are provided for a fuel system. In one example, a method may include cleaning an orifice of an ELCM. The cleaning includes adjusting a position of a valve in a passage to fluidly couple a reference orifice of the ELCM to an intake manifold.