Gm Global Technolgoy Operations, Inc.

Brett B Thompson

Stephen Paul Levijoki

Paul Jasinkiewicz

Yue-Yun Wang

Justin Adam Shetney

Cheryl Jeanette Stark

Scott R Gordon

An exhaust diagnostic system comprises a selective catalyst reduction (SCR) component testing module, an exhaust stream temperature management module, and a test enabling module. The component testing module executes an SCR component efficiency test. The exhaust stream temperature management module adjusts a temperature of the SCR component to a predetermined temperature range. The test enabling module executes a process for depleting a reductant load and subsequently initiates an SCR component efficiency test while the temperature of the SCR catalyst is within the predetermined temperature range. A method for diagnosing an exhaust system comprises determining an efficiency of an SCR component and selectively adjusting a temperature of the SCR component to a predetermined temperature range. The method also includes executing a process for depleting a reductant load and initiating an SCR component efficiency test while the temperature of the SCR component is within the predetermined temperature range.

Exhaust diagnostic system and method with SCR NH3 depletion cleansing mode for initial step in the def quality service healing test

A control system for a selective catalytic reduction (SCR) system includes a conversion efficiency determination module, an ammonia slip determination module, and a diagnostic module. The conversion efficiency determination module determines a conversion efficiency of an SCR catalyst. The ammonia slip determination module determines an amount of ammonia slip across the SCR catalyst when the conversion efficiency is less than a predetermined threshold. The diagnostic module determines pass/fail statuses of a reductant supply and the SCR catalyst based on the amount of ammonia slip and at least one ammonia slip threshold.

System and method for detecting low quality reductant and catalyst degradation in selective catalytic reduction systems

A diagnostic control module includes a temperature gradient module. The temperature gradient module determines a temperature gradient across a selective catalytic reduction (SCR) catalyst of an exhaust system of an engine based on a plurality of temperature signals. A calibration module determines a weighted average based on the plurality of temperature signals. A SCR efficiency control module disables conversion efficiency monitoring based on the temperature gradient and the weighted average.

Exhaust diagnostic systems and methods with SCR conversion efficiency monitor disabling

An exhaust diagnostic system includes a selective catalyst reduction (SCR) efficiency testing module that determines an efficiency of a SCR catalyst. An exhaust gas temperature management module selectively adjusts a temperature of the SCR catalyst to a predetermined temperature range using intrusive exhaust gas temperature management. A test enabling module initiates an SCR efficiency test using the SCR efficiency module after failing a prior SCR efficiency test and while the temperature of the SCR catalyst is within the predetermined temperature range.

Exhaust diagnostic systems and methods for resetting after operation with poor reductant quality

A glow plug control system for a vehicle comprises a mode control module and a fault diagnostic module. The mode control module enables one of a first mode and a second mode of operation based on a period of time that a glow plug is ON during a drive cycle. The fault diagnostic module selectively diagnoses a fault based on a first message, a second message, and a third message when the first mode is enabled and selectively diagnoses the fault independent of the second and third messages when the second mode is enabled.

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Farmington Hills, MI, United States of America

Brett B Thompson