Abstract: A method is described for identifying fuel composition from an index ratio of oxygen sensors upstream and downstream of a catalyst of the engine. Different index ratios are achieved for different fuel compositions, and thus it is possible to identify fuel composition, such as fuel alcohol content, based on changes in the index ratio.

Abstract: A method is described for operating an engine and an emission control system downstream of the engine, the emission control system including a catalyst, an exhaust gas path coupling the engine to the catalyst, a first air-fuel ratio sensor positioned upstream of the catalyst and a second air-fuel ratio sensor positioned adjacent to or downstream of the catalyst. The method includes correlating variation in the catalyst performance across air-fuel ratios, as identified via the first and second sensors, to fuel composition of fuel combusted in the engine.

Abstract: A system for determining a temperature of exhaust gases from an engine is provided. The system includes an exhaust gas sensor having an electric heating coil. The sensor communicates with exhaust gases from the engine. The system further includes an electrical circuit for generating a signal indicative of the resistance of the heating coil when the coil is not energized. Finally, the system includes a controller receiving the signal and calculating the temperature of the exhaust gases based on the signal.

Abstract: A method for determining the effectiveness of a catalyst to remove emissions from the exhaust of an internal combustion engine. The method includes measuring an upstream time history of a signal produced by an exhaust gas oxygen sensor upstream of the converter and a time history of an exhaust gas oxygen sensor disposed downstream of the converter. The time histories vary between a lean air-fuel ratio signal level and a rich air-fuel ratio signal level. A time delay is determined between the upstream time history and the downstream time history during transitions in such time histories from the lean air-fuel ratio signal level to the rich air-fuel ratio signal level. The determined time delay is compared with a reference time delay to determine the efficiency of the converter. The converter is determined to be ineffective if the converter as been determined to be potentially ineffective and the time delay is determined to be less than the reference time delay.

Abstract: A method for determining the effectiveness of a catalyst to remove emissions from the exhaust of an internal combustion engine. The method includes measuring an upstream time history of a signal produced by an exhaust gas oxygen sensor upstream of the converter and a time history of an exhaust gas oxygen sensor disposed downstream of the converter. The time histories vary between a lean air-fuel ratio signal level and a rich air-fuel ratio signal level. A time delay is determined between the upstream time history and the downstream time history during transitions in such time histories from the lean air-fuel ratio signal level to the rich air-fuel ratio signal level. The determined time delay is compared with a reference time delay to determine the efficiency of the converter. The converter is determined to be ineffective if the converter as been determined to be potentially ineffective and the time delay is determined to be less than the reference time delay.

Abstract: A system for determining a temperature of exhaust gases from an engine is provided. The system includes an exhaust gas sensor having an electric heating coil. The sensor communicates with exhaust gases from the engine. The system further includes an electrical circuit for generating a signal indicative of the resistance of the heating coil when the coil is not energized. Finally, the system includes a controller receiving the signal and calculating the temperature of the exhaust gases based on the signal.

Abstract: A system and method for detecting an air leak within an engine is provided. The engine includes an intake manifold communicating with an engine cylinder. The method includes measuring an exhaust gas constituent in exhaust gases from the engine when the engine is operating in an idle operating mode. The method further includes determining whether the air leak is present in the engine based on a measured exhaust gas constituent, a first air-fuel correction value, and a second air-fuel correction value.

Abstract: A method of determining the type of fuel being burned in an engine by analyzing the signal provided by a exhaust gas oxygen sensor signal is disclosed. The determination is based on the ratio of the value of certain characteristics of the signal during the lean and rich portions of the signal.

Abstract: A system and method for detecting an air leak within an engine is provided. The engine includes an intake manifold communicating with an engine cylinder. The method includes measuring an exhaust gas constituent in exhaust gases from the engine when the engine is operating in an idle operating mode. The method further includes determining whether the air leak is present in the engine based on a measured exhaust gas constituent, a first air-fuel correction value, and a second air-fuel correction value.

Abstract: A system and method for detecting an air leak within an exhaust system is provided. The method includes measuring an exhaust gas constituent in exhaust gases from the engine when the engine is operating in an idle operating mode. The method further includes determining whether the air leak is present in the exhaust system based on a measured exhaust gas constituent, a first air-fuel correction value, and a second air-fuel correction value.

Abstract: A method for determining the effectiveness of a catalyst having both first, relatively high oxidizable material provided to remove emissions from the exhaust of an internal combustion engine and a second, relatively low oxidizable material provided to remove emissions from such exhaust. The method includes measure a difference in oxygen content upstream and downstream of the catalyst while the engine is producing the exhaust to determine the effectiveness of the first material and determining the effectiveness of the second material by comparing time delay in a property of the exhaust as such exhaust passes through the catalyst. In one embodiment, the property of the exhaust is the oxygen content in such exhaust. In one embodiment, the effectiveness of the second material is measured after the first material is determined to be ineffective.

Abstract: A method of determining the type of fuel being burned in an engine by analyzing the signal provided by a exhaust gas oxygen sensor signal is disclosed. The determination is based on the ratio of the value of certain characteristics of the signal during the lean and rich portions of the signal.

Abstract: A catalytic monitoring method for an engine having two engine banks of which each coupled to one of two catalytic converters using first and second exhaust gas oxygen sensors respectively, upstream and downstream of one catalytic converter. Third and fourth exhaust gas oxygen sensors are respectively coupled upstream and downstream of the other catalytic converter. Switch ratios are determined for each of the engine banks based on the switching ratios of each upstream and downstream pair of exhaust gas oxygen sensors. A combination of the switch ratios is used to determine overall catalytic converter system performance.

Abstract: Method and system are provided for monitoring performance of a catalytic converter coupled to an exhaust of an internal combustion engine supplied with fuel from a fuel tank where the fuel can include a first fuel and second fuel in concentrations that vary from one refueling to the next. A ratio indicative of catalytic converter exhaust gas conversion efficiency is determined from signals provided by an exhaust gas sensor disposed upstream and an exhaust gas sensor disposed downstream relative to the catalytic converter, and a ratio threshold value indicative of a malfunctioning catalytic converter is adjusted in dependence on the concentration of one of the first fuel and second fuel in the fuel in the fuel tank.

Abstract: A system and method of normalizing an emissions threshold catalytic brick 302 without a mileage accumulation step is used to evaluate an on-board diagnostics for an exhaust system. The method comprises normalizing a emissions threshold catalytic brick 302 by placing the emissions threshold catalytic brick 302 in a exhaust gas circulation oven, such as a retort chamber 300, immediately after an oven-aging and chemical aging process wherein the emissions threshold catalytic brick 302 is saturated with a exhaust gas at a predetermined rate and at a predetermined temperature for a specified period of time based upon the characteristics desired for the emissions threshold catalytic brick. Additionally, a method for evaluating on-board diagnostics of an exhaust system using an emissions threshold catalytic brick 302 based upon the characteristics of the exhaust system that it will be placed in is also contemplated.

Abstract: A method of detecting catalytic converter deterioration based on the ratio of the arc length or the number of transitions of signals from sensors upstream and downstream of the converter where ratio determination is restricted to predefined air mass ranges within corresponding predefined engine speed/load ranges in order to avoid areas of engine speed and load instability that might impair test to test repeatability of the deterioration detection.

Abstract: A catalytic monitoring method for an engine having two engine banks of which each coupled to one of two catalytic converters using first and second exhaust gas oxygen sensors, respectively upstream and downstream of one catalytic converter. Third and fourth exhaust gas oxygen sensors are respectively coupled upstream and downstream of the other catalytic converter. Switch ratios are determined for each of the engine banks based on the switching ratios of each upstream and downstream pair of exhaust gas oxygen sensors. A combination of the switch ratios is used to determine overall catalytic converter system performance.

Abstract: An adaptive catalytic monitoring method for an engine having two engine banks each coupled to one of two catalytic converters uses first and second exhaust gas oxygen sensors respectively upstream and downstream of one catalytic converter. Third and fourth exhaust gas oxygen sensors are respectively coupled upstream and downstream of the other catalytic converter. Switch ratios are determined for each of the engine banks based the switching ratios of each upstream and downstream pair of exhaust gas oxygen sensors, with the switch ratio being adjusted by an adjustment gain that is a function of airflow and a catalytic converter characteristic. A combination of the adjusted switch ratios is used to determine overall catalytic converter system performance.

Abstract: A system and method for monitoring catalytic converter efficiency monitor the switch ratio of upstream and downstream exhaust gas oxygen sensors based on an acceptable temperature range of the catalytic converter. In one embodiment, catalytic converter temperature is determined based on exhaust gas temperature. The exhaust gas temperature may be used to infer the temperature of the catalytic converter mid-bed. The efficiency may be determined based on a correspondence with a number of mass air flow ranges. The system and method may also use vehicle speed and EGR to assure that the monitor samples data during repeatable, robust load-speed-temperature conditions. Switch data is stored in keep-alive memory to increase the confidence of the efficiency determination due to a larger data collection phase. A filter having a cycle based constant may be used to filter a current switch ratio before incorporating it into an average switch ratio.

Abstract: A system and method for monitoring emissions by monitoring performance of a catalytic converter using a predetermined indicated threshold value include determining a current value for the indicator based on signals generated by at least one exhaust gas sensor, modifying a historical indicator value based on the current value, and adjusting the predetermined indicator threshold based on the historical indicator value. The predetermined indicator threshold is adjusted provided various adapt criteria are satisfied. The historical indicator value is compared to the threshold to determine whether to generate a malfunction indicator signal. In one embodiment, emissions are indicated using a switch ratio based on the number of switches or transitions for upstream and downstream exhaust gas oxygen sensors.