METHODS AND SYSTEM FOR DIAGNOSING SENSORS BY UTILIZING AN EVAPORATIVE EMISSIONS SYSTEM
First Claim
1. A method, comprising:
- during a first condition when an engine is combusting fuel, adjusting engine operation based on an output of a sensor disposed in an intake of the engine; and
during a second condition when the engine is off, indicating degradation of the sensor based on an output of the sensor while flowing air from an evaporative emissions system past the sensor.
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Accused Products
Abstract
Methods and systems are provided for diagnosing sensors in an engine intake by utilizing in an evaporative leak check module pump (ELCM pump). In one example, during engine off conditions, the ELCM pump in an evaporative emission system of the vehicle may be operated in a pressure mode to flow ambient air from the evaporative emissions system to the intake manifold. During humidity sensor diagnostics, the air flow may be used to generate water vapors within the intake manifold, and humidity sensor may be rationalized by monitoring an output of the humidity sensor; and during MAF sensor diagnostics, MAF sensor may be rationalized by monitoring if the MAF sensor output corresponds to a flow rate generated by the ELCM.
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Citations
20 Claims
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1. A method, comprising:
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during a first condition when an engine is combusting fuel, adjusting engine operation based on an output of a sensor disposed in an intake of the engine; and during a second condition when the engine is off, indicating degradation of the sensor based on an output of the sensor while flowing air from an evaporative emissions system past the sensor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method, comprising:
during an engine off period, in response to engine coolant temperature decreasing to a threshold temperature; flowing heated and pressurized ambient air from an evaporative emissions system to an intake passage; and indicating degradation of a humidity sensor disposed in the intake passage in response to an output of the humidity sensor not changing by a threshold amount. - View Dependent Claims (16, 17)
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18. A method, comprising:
during an engine-off condition, responsive to a fuel vapor canister load less than a threshold and an engine coolant temperature within a threshold temperature range of an engine intake air temperature; isolating a fuel vapor canister from a fuel tank; coupling the fuel vapor canister to atmosphere via an evaporative leak check module vacuum pump; activating the evaporative leak check module vacuum pump in a conformation to pump atmospheric air into the fuel vapor canister; opening a canister purge valve; opening an air intake throttle; and indicating degradation of a MAF sensor disposed in an intake manifold in response to an output of the MAF sensor being outside of a threshold range. - View Dependent Claims (19, 20)
Specification