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Manufacturers have used a number of alternative emission control technologies to meet the emission standards for 1981 and later model years. Each technology type can have malperformances that lead to high emissions, but the ability of inspection/maintenance short tests to identify high emitters varies considerably by technology. In this study, the relationships between malperformance types, FTP emissions and short test emissions were identified for several major technology types, using data from the EPA Emission Factor data base. Based on these relationships, methods to enhance the effectiveness of I/M tests are suggested. The analysis indicated that the most important factor governing the ability of any I/M short test is the presence of absence of secondary air. The short tests were found to be incapable of recognizing any malperformance except severe misfire if secondary air was present.

In this paper, a model condensation technique is developed to ensure consistent modeling of STL (Sound Transmission Loss) between coarse and detailed SEA model. In the Performance-Based coarse SEA Model, the component level performance (STL and absorption) is assigned to each path, which comes from various ways including detailed analytical SEA model. From the detailed SEA model for the component or even the whole vehicle, the equivalent performance data needs to be condensed and extracted for the coarse model. The condensation theory for equivalent STL is presented in this paper. The extra work needed to apply this technique to detailed SEA model is negligible by using AutoSEA script. An example for condensation of a detailed component model is given at the end. Comparison between the detailed analytical SEA model and the coarse SEA Model is consistent.