SOUTHWEST RESEARCH INSTITUTE

Home

Site Map

	Image of EGR restrictor plates

With a goal to meet on-board diagnostics (OBD)-II regulations for light-duty diesel passenger vehicles, Southwest Research Institute (SwRI) engineers developed methods to simulate three exhaust gas recirculation (EGR) system faults:

• Reduced EGR cooling

• EGR gas leaks

• EGR gas flow restriction

Each failure mode was tested over the 13-mode ESC steady-state test cycle to determine the effect on NOx emissions, and to determine if a particular failure mode required a comprehensive component monitor or a threshold monitor.

	One obstacle to overcome in this study was controlled aging and failure of parts.

It was determined that reduced cooling and leak faults only required comprehensive component monitoring. EGR gas flow restrictions, however, required a threshold monitor. Data from sensors commonly found on heavy-duty engines were evaluated to determine if these sensors were sufficient to provide a metric to detect an EGR restriction fault at the OBD threshold value.

Three metrics were evaluated:

• Mass air flow (MAF)

• Exhaust gas oxygen concentration (%O₂)

• Intake manifold temperature

It was determined that percent O₂ was not a viable metric to detect an EGR fault, but MAF and intake manifold temperature were sufficient. Diagnostic algorithms using MAF and intake manifold temperature were developed and implemented in MATLAB^®/Simulink^®. The intake manifold temperature was found to be more robust than MAF during this testing. The diagnostic monitor using intake manifold temperature performed very well during steady-state and quasi-transient operation, but may require additional refinement to reduce false detections under transient operation and during in-field operation.

For more information about our powertrain control capabilities, or how you can contract with SwRI, please contact Jayant Sarlashkar at jsarlashkar@swri.org or (210) 522-5506.

powertraincontroltech.swri.org

| Engine and Vehicle R&D Department | Engine, Emissions & Vehicle Research Division | SwRI Home |

Southwest Research Institute^® (SwRI^®), headquartered in San Antonio, Texas, is a multidisciplinary, independent, nonprofit, applied engineering and physical sciences research and development organization with 11 technical divisions.

December 28, 2012