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Twenty in-use vehicles that had failed the I/M test in the State of Michigan were inspected for engine mechanical condition as well as the state of the emission control system. Mass emission tests were conducted before and after repairs to the emission control system. The internal engine condition (i.e., high or low levels of cylinder leakage, or compression difference) showed little effect on the ability of the repaired vehicles to achieve moderate mass emission levels. Nine of the twenty vehicles were recruited after three years, and with the exception of tampering, the original emission control system repairs proved to be durable.

This is a summary compilation and analysis of exhaust-emission results and operating parameters from forty-five heavy-duty gasoline and diesel-powered vehicles tested over a 7.24-mile road course known as the San Antonio Road Route (SARR); and, for correlative purposes, on a chassis dynamometer.(2) Exhaust samples were collected and analyzed using the Constant Volume Sampler (CVS) technique similar to that used in emission testing of light-duty vehicles. On the road course, all equipment and instrumentation were located on the vehicle while electrical power was supplied by a trailer-mounted generator. In addition to exhaust emissions, operating parameters such as vehicle speed, engine speed, manifold vacuum, and transmission gear were simultaneously measured and recorded on magnetic tape. The forty-five vehicles tested represent various model years, GVW ratings, and engine types and sizes.

This, the fourteenth in this series of papers, examines trends in fuel economy, technology usage and estimated 0 to 60 MPH acceleration time for model year 1986 passenger cars. Comparisons with previous year's data are made for the fleet as a whole and using three measures of vehicle/engine size: number of cylinders, EPA car class, and inertia weight class. Emphasis on vehicle performance and fuel metering has been expanded and analysis of individual manufacturers has been deemphasized; comparisons of the Domestic, European, and Japanese market sectors are given increased emphasis.

A Sequential fuel injection system was fitted to a 2 liter Nissan NAPS-Z engine that had been modified for neat methanol operation. The specific modifications for high compression operation with neat methanol are described, and baseline brake thermal efficiency and engine out emissions are established. Sequential injection operation on neat methanol included varying the beginning of injection between 50°BTDC and 250°ATDC over an equivalence ratio of 0.6 to 0.9. Efficiency and emission results with the Sequential system are compared to those from the base system and from selected references. For the low speed, steady state conditions used in this program, the Sequential system did not show any general improvement in efficiency or emissions. This result is directionally opposite to that observed in one reference. The apparent cause for the divergent results is the absence of mechanisms in this experiment to prevent mixing along the cylinder axis.

An inexpensive system was designed that would allow repair shops to verify the adequacy of repairs made to cars that had previously failed the new high-tech I/M test (IM240). Before and after repair tests on a limited number of vehicles were performed with both official IM240 and prototype repair grade (RG240) equipment systems. Analyses were performed to determine if the RG240 system concept is capable of determining if the repairs performed resulted in adequate emissions reductions to assure a passing IM240 retest. This study focuses on development of a prototype RG240 system consisting of a 100 SCFM CVS, a dynamometer with an eddy current power absorber and non-adjustable 2000 pound inertia flywheel, and a BAR 90 emissions analyzer with an additional nitric oxide analyzer.