Diagnosis for multiple cylinder engine
AssigneesMazda Motor Corporation, Ford Global Technologies, LLC
InventorsHajime Suetsugu, Kenji Kojima, Tetsushi Hosokai, John D. Russell
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Abstract
Methods and systems for diagnosing a multiple cylinder engine are provided herein. An exemplary method of diagnosing an internal combustion engine system having a multi-cylinder internal combustion engine is described. In one example, cylinder air-fuel imbalance is determined from the squared value of a difference of two values.
Claims21
A method of diagnosing an internal combustion engine system having a multi-cylinder internal combustion engine and an air fuel ratio sensor which detects an air fuel ratio of mixed exhaust gas flowing from the multiple cylinders and outputs a signal corresponding to said detected air fuel ratio, the method comprising:
- computing a square value of a difference between two values, said air fuel ratio sensor outputting said two values at discrete timings within a predetermined period;
- integrating said square value over predetermined times;
- and
- diagnosing said internal combustion engine system based on said integrated square value.
A method of diagnosing an internal combustion engine system having a multi-cylinder internal combustion engine and an air fuel ratio sensor which detects an air fuel ratio of mixed exhaust gas flowing from the multiple cylinders and outputs a signal corresponding to said detected air fuel ratio, the method comprising:
- computing a square value of a difference between two values, said air fuel ratio sensor outputting said two values at a predetermined interval;
- integrating said square value over a predetermined time;
- and
- diagnosing said internal combustion engine system based on said integrated square value.
A method of diagnosing an internal combustion engine system having a multi-cylinder internal combustion engine and an air fuel ratio sensor which detects an air fuel ratio of mixed exhaust gas flowing from the multiple cylinders and outputs a signal corresponding to said detected air fuel ratio, the method comprising:
- computing a square value of a difference between a maximum value and a minimum value output by said air fuel ratio sensor over a cylinder cycle;
- and
- diagnosing said internal combustion engine system based on said square value.
A system for diagnosing an internal combustion engine system having a multi-cylinder internal combustion engine and an air fuel ratio sensor which detects an air fuel ratio of mixed exhaust gas flowing from the multiple cylinders, and outputs a signal corresponding to said detected air fuel ratio, comprising:
- a tester configured to:
- compute a square value of a difference between two values, said air fuel ratio sensor outputting said two values at a predetermined interval;
- integrate said square value over predetermined times;
- and
- diagnose said internal combustion engine system based on said integrated square value.
Dependencies are inferred from the claim text.