Variable displacement engine diagnostics
First Claim
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1. A method for monitoring cylinder valve deactivation of a cylinder valve of an engine, comprising:
- setting a diagnostic code in a control system indicating degradation of cylinder valve deactivation in response to a manifold pressure response to cylinder valve events, the manifold pressure response at or around a characteristic frequency and during an intake valve event of the engine, the characteristic frequency including a resonant acoustic frequency of an engine intake manifold.
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Abstract
Methods and systems are provided for monitoring cylinder valve deactivation of a cylinder valve of an engine. One example method comprises, indicating degradation of cylinder valve deactivation in response to manifold pressure at or around a characteristic frequency.
61 Citations
16 Claims
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1. A method for monitoring cylinder valve deactivation of a cylinder valve of an engine, comprising:
setting a diagnostic code in a control system indicating degradation of cylinder valve deactivation in response to a manifold pressure response to cylinder valve events, the manifold pressure response at or around a characteristic frequency and during an intake valve event of the engine, the characteristic frequency including a resonant acoustic frequency of an engine intake manifold. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for monitoring a cylinder valve deactivation mechanism coupled in an engine, the cylinder valve deactivation mechanism coupled to at least a cylinder valve of a cylinder of the engine, the cylinder having a plurality of cylinder valves with variable cam timing, the method comprising:
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monitoring a signal indicative of intake manifold pressure of the engine; sampling the signal at least over a movable crank angle window, the crank angle window adjusted responsive to adjustments in cam timing; and indicating degradation of the cylinder valve deactivation mechanism in response to a magnitude of the sampled signal at or around a characteristic resonant frequency of the intake manifold pressure. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A system, comprising:
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an engine having a crankshaft and a plurality of cylinders, each cylinder with a plurality of cylinder valves; a deactivation mechanism for deactivating at least one cylinder valve; a variable cam timing mechanism for adjusting a timing of at least one cylinder valve; an intake manifold; a sensor providing information indicative of manifold pressure; and a control system configured to receive a signal from the sensor, sample the signal indicative over a movable crank angle window, the crank angle window adjusted responsive to adjustments in cam timing and including an intake stroke of a cylinder of the engine, indicate degradation of the valve deactivation mechanism in response to a magnitude of the sampled signal at or around a characteristic resonant frequency of the intake manifold pressure, and to differentiate valve degradation among the plurality of cylinder valves of the engine based on the signal content and a crank angle at which the signal content is greater than a threshold amount. - View Dependent Claims (16)
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Specification