| 摘要 |
A method for diagnosing an operational state of a variable valve lift (VVL) device in an engine, wherein the VVL device is capable of operating in two modes of operation. The method includes measuring a rotational speed of an engine crankshaft while the engine is running or cranking, correlating the measured crankshaft speed with an estimated engine cylinder pressure or torque, comparing the estimated engine cylinder pressure or torque with an expected range of engine cylinder pressure or torque values for the two modes of operation for the VVL device, determining if the estimated engine cylinder pressure or torque falls within the expected range of engine cylinder pressure or torque values, and activating an alert if the estimated engine cylinder pressure or torque falls outside the expected range of engine cylinder pressure or torque values to provide notification that the VVL device is operating in an improper mode of operation.
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