Engine diagnostics with skip fire control
First Claim
1. A method of operating an internal combustion engine having a plurality of cylinder banks, each bank including a plurality of cylinders, the method comprising:
- operating the engine in a skip fire operational mode that utilizes most evenly spaced firings;
while operating in the skip fire operational mode, identifying a period in which a single one of the cylinders in a first cylinder bank is isolated as the only firing cylinder in the first cylinder bank; and
conducting a diagnosis of the isolated cylinder during the identified period, wherein the diagnosis conducted on the isolated cylinder is not conducted on the isolated cylinder when such cylinder is not isolated.
1 Assignment
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Accused Products
Abstract
Methods and devices are described for performing engine diagnostics during skip fire operation of an engine while a vehicle is being driven. Knowledge of the firing sequence is used to determine appropriate times to conduct selected diagnostics and/or to help better interpret sensor inputs or diagnostic results. In one aspect, selected diagnostics are executed when a single cylinder is fired a plurality of times in isolation relative to a sensor used in the diagnosis. In another aspect, selected diagnostics are conducted while the engine is operated using a firing sequence that insures that no cylinders in a first cylinder bank are fired for a plurality of engine cycles while cylinders in a second bank are at least sometimes fired. The described tests can be conducted opportunistically, when conditions are appropriate, or specific firing sequences can be commanded to achieve the desired isolation or skipping of one or more selected cylinders.
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Citations
24 Claims
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1. A method of operating an internal combustion engine having a plurality of cylinder banks, each bank including a plurality of cylinders, the method comprising:
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operating the engine in a skip fire operational mode that utilizes most evenly spaced firings; while operating in the skip fire operational mode, identifying a period in which a single one of the cylinders in a first cylinder bank is isolated as the only firing cylinder in the first cylinder bank; and conducting a diagnosis of the isolated cylinder during the identified period, wherein the diagnosis conducted on the isolated cylinder is not conducted on the isolated cylinder when such cylinder is not isolated. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of managing fuel injector trim while a vehicle is being driven, the vehicle having an internal combustion engine having a multiplicity of cylinders, each cylinder having an associated fuel injector, the method comprising:
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operating the engine in a skip fire operational mode during normal driving operation of the vehicle; for each cylinder, conducting an individual cylinder fuel trim diagnosis for the injector associated with such cylinder during the skip fire operation of the engine; and adjusting a fuel trim of at least one of the fuel injectors based of the individual cylinder fuel trim diagnoses. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15)
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16. A method of operating a vehicle having an internal combustion engine having a plurality of cylinder banks, each bank including a plurality of cylinders, the method comprising:
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while the vehicle is being driven, operating the engine using a skip fire firing sequence that insures that no cylinders in a first cylinder bank are fired over a period of time that includes a plurality of engine cycles while cylinders in a second bank are at least sometimes fired; and conducting a diagnosis of a component in an exhaust path associated with the first bank of cylinders, wherein at least a significant portion of the diagnosis is conducted while the cylinders in the first bank are not being fired. - View Dependent Claims (17, 18, 19, 20, 21, 22)
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23. An engine controller configured to control operation of an internal combustion engine having a multiplicity of cylinders, each cylinder having an associated fuel injector, the engine further comprising an oxygen sensor located in an exhaust path associated with a plurality of the cylinders, wherein the engine controller is arranged to perform individual fuel injector trim tests while a vehicle that include the internal combustion engine is being driven, the engine controller configured to:
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(a) during normal driving conditions, direct operation of the engine at a firing fraction or firing sequence that causes a first one of the cylinders associated with the oxygen sensor to be isolated as the only cylinder associated with the oxygen sensor that is fired over the course of a plurality of engine cycles; (b) conduct an individual cylinder fuel trim diagnosis for the fuel injector associated with the isolated cylinder using the oxygen sensor; repeat steps (a) and (b) for each of the cylinders associated with the oxygen sensor. - View Dependent Claims (24)
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Specification