Systems and methods for engine control
First Claim
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1. A method, comprising:
- while operating an engine with EGR, adjusting spark responsive to an indication of knock;
responsive to the adjusted spark being retarded to a spark retard threshold, integrating knock sensor output over a number of engine cycles and determining a fuel control correction over the number of engine cycles; and
indicating degradation of an EGR system responsive to one or more of the integrated output of the knock sensor being greater than a first threshold and the fuel control correction being greater than a second threshold.
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Abstract
Methods and systems are provided for adjusting spark timing and fueling in an engine in response to an indication of exhaust gas recirculation (EGR) system degradation due to a disconnected upstream hose of an EGR differential pressure sensor. In one example, a method may include, responsive to an integrated knock intensity being greater than a threshold intensity and a fuel control correction being greater than a threshold enrichment, setting an EGR rate to zero and triggering an EGR differential pressure sensor upstream hose diagnostic routine to be performed. Further, spark timing and fueling may be set for zero EGR.
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Citations
11 Claims
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1. A method, comprising:
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while operating an engine with EGR, adjusting spark responsive to an indication of knock; responsive to the adjusted spark being retarded to a spark retard threshold, integrating knock sensor output over a number of engine cycles and determining a fuel control correction over the number of engine cycles; and indicating degradation of an EGR system responsive to one or more of the integrated output of the knock sensor being greater than a first threshold and the fuel control correction being greater than a second threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A system, comprising:
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an engine having a cylinder; an intake manifold and an exhaust system; an EGR system, comprising an EGR passage fluidically coupling the intake manifold to the exhaust system, the EGR passage including a restrictive orifice, an EGR valve coupled to the EGR passage, and a differential pressure sensor for sensing EGR flow, the sensor including an upstream hose coupled to the EGR passage, upstream of the restrictive orifice, and a downstream hose coupled to the EGR passage, downstream of the restrictive orifice; a spark plug for providing spark to the cylinder; a knock sensor; a manifold absolute pressure (MAP) sensor coupled to the intake manifold for estimating an engine airflow; an exhaust gas oxygen sensor coupled to the exhaust system; and a controller configured with computer readable instructions stored on non-transitory memory for; operating the engine with an EGR flow; estimating a cylinder air amount based on each of the engine airflow and the EGR flow; calculating each of a fuel command based on the cylinder air amount and a correction to the fuel command based on exhaust gas oxygen sensor output; calculating a spark timing based in part on the EGR flow; detecting knock based on output of the knock sensor; retarding spark from the determined spark timing in response to knock detection; and indicating potential disconnection of the upstream hose from at least one of the EGR passage and the differential pressure sensor responsive to each of the correction to the fuel command being greater than a threshold enrichment, an integrated output of the knock sensor being greater than a threshold intensity, and spark retard reaching a spark retard threshold. - View Dependent Claims (9, 10, 11)
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Specification