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The Environmental Protection Agency (EPA) is developing emission standards for nonroad spark-ignition engines rated over 19 kW. Existing emission standards adopted by the California Air Resources Board for these engines were derived from emission testing with new engines, with an approximate adjustment applied to take deterioration into account. This paper describes subsequent testing with two LPG-fueled engines that had accumulated several thousand hours of operation with closed-loop control and three-way catalysts. These engines were removed from forklift trucks for characterization and optimization of emission levels. Emissions were measured over a wide range of steady-state points and several transient duty cycles. Optimized emission levels from the aged systems were generally below 1.5 g/hp-hr THC+NOx and 10 g/hp-hr CO.

A Repeatable Car (REPCA) program has been developed at the Environmental Protection Agency's National Vehicle and Fuel Emissions Laboratory (NVFEL) as part of an ongoing effort to improve the precision of fuel economy and emissions measurements. This concept of using a repeatable car as an integrated system diagnostic tool is not a new idea in the emissions testing field; however, our statistical analyses and organizational approach may be different from what other laboratories are using. Furthermore, given the NVEFL's role in automotive emissions testing, we felt it appropriate to provide related industries a detailed account of our standard laboratory practices, both for informational and comparative purposes. In order to separate vehicle and measurement variability in a relatively simple manner, a process was developed to track REPCA data based on Statistical Process Control principles using the calculation of individual site offset values from two week moving averages.

Motor vehicles are seldom used in ambient conditions like those defined in current emission regulations. For example, most of the year average temperatures across Europe fall much below the range of legislative testing. Furthermore, it has been widely demonstrated that cold-starts at low ambient temperature increase the emissions. Therefore, there is a growing need to broaden the range of legislative emissions tests and set a separate low-ambient test with respective emission standards. This paper gives emissions test results form a joint research programme between Sweden and Finland. Altogether 11 late model gasoline-fueled TWC vehicles were tested at ambient temperatures of +22 and -7 °C using a variety of different driving cycles. Apart from the driving schedule, other test parameters like vehicle preconditioning, manual vs. automatic transmission and the effect of external cooling were studied and discussed.

This paper summarizes an investigation of reductions in exhaust emission levels attainable using various techniques appropriate to gasoline engines used in vehicles over 14,000 lbs GVW. Of the eight gasoline engines investigated, two were evaluated parametrically resulting in an oxidation and reduction catalyst “best combination” configuration. Four of the engines were evaluated in an EGR plus oxidation catalyst configuration, and two involved only baseline tests. Test procedures used in evaluating the six “best combination” configurations include: three engine emission test procedures using an engine dynamometer, a determination of vehicle driveability, and two vehicle emission test procedures using a chassis dynamometer. Dramatic reductions in emissions were attained with the catalyst “best combination” configurations. Engine durability, however, was not investigated.

A fleet of 64 heavy-duty 1970-71 model trucks and buses powered by a variety of diesel engines were tested periodically to determine exhaust smoke behavior. Smoke tests were made when the vehicle was new or nearly new and at four month intervals thereafter, or until 160,934 km (100,000 miles) odometer reading was reached. Gaseous emissions of hydrocarbon (HC), carbon monoxide (CO), and nitric oxide (NO) were measured at one point early in the project. Both smoke and gaseous emission tests were performed with chassis versions of the engine dynamometer Federal Test Procedures (FTP). Results in terms of “a” (acceleration), “b” (lugging), and “c” (peak) smoke factors versus mileage are reported for the 13 engine-vehicle-application groupings.

Evaporative emission tests were performed on forty in-use late model passenger cars using different volatility fuels and varying temperatures. Results show that diurnal and hot soak emissions are quite sensitive to temperature, and also that the temperature sensitivity increases with the use of higher volatility fuels. Empirical models were developed to express diurnal and hot soak emissions as a function of fuel volatility and temperature.