Abstract: Methods and systems are provided for a diagnostic routine of a variable displacement engine (VDE) of a vehicle to detect non-deactivated valves of deactivated cylinders due to a degraded valve deactivation mechanism. In one example, a method comprises, during operation of the VDE with one or more cylinders of the VDE deactivated, calculating a variation in a fast-sampled signal outputted by one or more exhaust gas oxygen (EGO) sensors of the VDE over a plurality of engine cycles; determining that the variation is greater than the threshold variation; and in response, indicating that valves of the one or more cylinders are not deactivated. A second method comprises estimating a throttle air flow rate and an engine air flow rate of the VDE; and indicating non-deactivated valves of one or more deactivated cylinders if the throttle air flow rate exceeds the engine air flow rate by a threshold.

Abstract: A method for purging a fuel vapor canister, comprising: responsive to an indication of vapor slugs, reversing a direction of air flow through the fuel vapor canister while maintaining purge air intake at a vent line inlet. By reversing the direction of air flow through the fuel vapor canister, the vapor slugs may be adsorbed within the fuel vapor canister and may not affect engine operation. In this way, purge operation may be maintained and emissions may be reduced.

Abstract: A method for purging a fuel vapor canister, comprising: responsive to an indication of vapor slugs, reversing a direction of air flow through the fuel vapor canister while maintaining purge air intake at a vent line inlet. By reversing the direction of air flow through the fuel vapor canister, the vapor slugs may be adsorbed within the fuel vapor canister and may not affect engine operation. In this way, purge operation may be maintained and emissions may be reduced.

Abstract: Systems and methods are provided for monitoring reverse flow of fuel vapors and/or air through a vehicle fuel vapor recovery system, said fuel vapor recovery system coupled to an engine intake of a boosted internal combustion engine. One example method comprises, during boost, when the fuel vapor recovery system is commanded to be sealed from the intake, indicating degradation based on a pressure value at a venturi in the fuel vapor recovery system.

Abstract: Systems and methods are provided for monitoring reverse flow of fuel vapors and/or air through a vehicle fuel vapor recovery system, said fuel vapor recovery system coupled to an engine intake of a boosted internal combustion engine. One example method comprises, during boost, when the fuel vapor recovery system is commanded to be sealed from the intake, indicating degradation based on a pressure value at a venturi in the fuel vapor recovery system.

Abstract: Systems and methods are provided for monitoring reverse flow of fuel vapors and/or air through a vehicle fuel vapor recovery system, said fuel vapor recovery system coupled to an engine intake of a boosted internal combustion engine. One example method comprises, during boost, when the fuel vapor recovery system is commanded to be sealed from the intake, indicating degradation based on a pressure value in the fuel vapor recovery system.

Abstract: Systems and methods are provided for monitoring reverse flow of fuel vapors and/or air through a vehicle fuel vapor recovery system, said fuel vapor recovery system coupled to an engine intake of a boosted internal combustion engine. One example method comprises, during boost, when the fuel vapor recovery system is commanded to be sealed from the intake, indicating degradation based on a pressure value in the fuel vapor recovery system.