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Due to its high efficiency and superior durability the diesel engine is again becoming a prime candidate for future light-duty vehicle applications within the United States. While in Europe the overall diesel share exceeds 40%, the current diesel share in the U.S. is 1%. Despite the current situation and the very stringent Tier 2 emission standards, efforts are being made to introduce the diesel engine back into the U.S. market. In order to succeed, these vehicles have to comply with emissions standards over a 120,000 miles distance while maintaining their excellent fuel economy. The availability of technologies such as high-pressure common-rail fuel systems, low sulfur diesel fuel, NOx adsorber catalysts (NAC), and diesel particle filters (DPFs) allow the development of powertrain systems that have the potential to comply with the light-duty Tier 2 emission requirements. In support of this, the U.S.

Six heavy-duty diesel engines were tested for exhaust emissions on the ISO 8-mode nonroad steady-state duty cycle and the U.S. FTP highway transient test cycle. Two of these engines were baseline nonroad engines, two were Tier 1 nonroad engines, and two were highway engines. One of the Tier 1 nonroad engines and both of the highway engines were also tested on three transient cycles developed for nonroad engines. In addition, published data were collected from an additional twenty diesel engines that were tested on the 8-mode as well as at least one transient test cycle. Data showed that HC and PM emissions from diesel engines are very sensitive to transient operation while NOx emissions are much less so. Although one of the nonroad transient duty cycles showed lower PM than the steady-state duty cycles, all four of the other cycles showed much higher PM emissions than the steady-state cycle.

This paper describes a method used to compare the emissions from transient operation of an engine with the emissions from steady state operating modes of the engine. Weightings were assigned to each mode based on the transient cycle under evaluation. The method of assigning the weightings for each mode took into account several factors, including the distance between each second of the transient cycle's speed-and-torque point requests (in a speed vs. torque coordinate system) and the given mode. Two transient cycles were chosen. The transient cycles were taken from actual in-use data collected on nonroad engines during in-field operation. The steady state modes selected were based on both International Standard Organization (ISO) test modes, as well as, augmentation based on contour plots of the emissions from nonroad diesel engines. Twenty-four (24) steady-state modes were used. The transient cycle's speed-and-torque points are used to weight each steady state mode in the method.

Eleven experienced commercial automotive technicians were recruited and trained to repair IM240 emission failures using a specially developed 30 hour course. The training course emphasized the use of an oscilloscope and a flow chart and wave form strategy to repair vehicles. Each technicians' performance was evaluated based on the repair of three or four in-use Arizona IM240 failures. Pre-training and post-training written tests were also administered. Results from this limited study were encouraging. After the technician training, HC and CO emission levels were reduced by 69% and NOx by 58%. More importantly, most of the technicians learned some new and useful diagnostic and equipment skills which they can immediately apply to their businesses. They also became more motivated to tackle the challenge of repairing vehicles to low transient emissions, and aware of the existence and use of new sophisticated diagnostic tools such as oscilloscopes.

Six in-use vehicles were tested on a baseline gasoline and nine gasoline/ethanol blends to determine the effect of ethanol content in fuels on automotive exhaust emissions and fuel economy. The baseline gasoline was representative of average summer gasoline and served as the base from which the other fuels were blended. For the majority of the vehicles, total hydrocarbon, and carbon monoxide exhaust emissions as well as fuel economy decreased while NOx and acetaldehyde exhaust emissions increased as the ethanol content in the test fuel increased. Formaldehyde and carbon dioxide emissions were relatively unaffected by the addition of ethanol. The emission responses to the increased fuel oxygen levels were consistent with what would be expected from leaning-out the air/fuel ratio for a spark ignition engine. The results are shown graphically and a linear regression is performed utilizing the method of least squares to investigate statistically significant trends in the data.

EPA published the first results from evaluations of electrically heated catalyst (EHC) technology for light-duty automotive applications. Since then, a number of automakers, suppliers, and government agencies have published results from their heated catalyst development and evaluation programs. EPA has evaluated a number of start catalyst systems incorporating an EHC start catalyst followed by a larger, conventional main catalyst. These systems have proven very effective at reducing cold start related emissions from methanol vehicles at low mileage. This paper compares the results from several EHC + main catalyst evaluations conducted by EPA.

The cyclic and steady-state vehicle emissions, fuel economy, performance, and cold start behavior of an automobile equipped with a direct injection methanol engine are compared with those of three other comparable vehicles. One of the comparable vehicles was powered by a gasoline-fueled engine, and the other two were Diesels. One of the Diesel-powered vehicles was naturally aspirated and the other was turbocharged. All evaluations were made using the same road load horsepower and equivalent test weight. All the evaluations were conducted at low mileage. The emissions of the methanol vehicle are compared to California low emission vehicle standards, and to the emissions of another methanol vehicle.

Simple tests were performed to investigate the operating characteristics of zirconia galvanic cells (lambda sensors) in automotive closed loop “three-way” emission control systems. Commercially available cells were exposed to typical gaseous components of exhaust gas mixtures. The voltages generated by the cells were at their maximum values when hydrogen, and, in some instances, carbon monoxide, was available for reaction with atmospheric oxygen that migrated through the cells' ceramic thimbles in ionic form. This dependence of galvanic activity on the availability of these particular reducing agents indicated that the cells were voltaic devices which operated as oxidation/reduction reaction cells, rather than simple oxygen concentration cells.

The application of resistive materials as part of an exhaust emission control system is presented and discussed. The importance of cold start emissions is emphasized, and results are presented from experiments conducted with two different conductive materials. Most of the testing was conducted using methanol as the fuel, although some tests were run using gasoline-fueled vehicles.

A Methanol catalyst test program has been conducted in two phases. The purpose of Phase I was to determine whether a base metal or lightly-loaded noble metal catalyst could reduce Methanol engine exhaust emissions with an efficiency comparable to conventional gasoline engine catalytic converters. The goal of Phase II was the reduction of aldehyde and unburned fuel emissions to very low levels by the use of noble metal catalysts with catalyst loadings higher than those in Phase I. Catalysts tested in Phase I were evaluated as three-way converters as well as under simulated oxidation catalyst conditions. Phase II catalysts were tested as three-way converters only. For Phase I, the most consistently efficient catalysts over the range of pollutants measured were platinum/rhodium configurations. None of the catalysts tested in Phase I were able to meet a NOx level of 1 gram per mile when operated in the oxidation mode.

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.

The increased interest in use of methanol makes it important to determine what levels of methanol and formaldehyde emissions may be acceptable. This paper reviews the available health data for methanol and formaldehyde to define what approximate ranges of concentrations, termed ranges of concern, could be acceptable from a toxicological viewpoint. Air quality models are then used to predict the in-use fleet average exhaust emission levels in localized situations (heavily impacted by mobile sources) corresponding to these ranges of concern. Using predicted fleet compositions, approximate target emission levels are given for the light-duty portion of the fleet which could yield these fleet averages. Finally, there is a brief summary of available methanol and formaldehyde emissions data from neat methanol-fueled vehicles which are compared to the target levels.

Studies of emissions from vehicles equipped with catalysts have shown that some unregulated emissions can increase when a catalyst is used. One example of this is sulfuric acid, which has been studied extensively. Other unregulated emissions include ammonia and hydrogen cyanide. In a number of studies, these unregulated pollutant emissions have been measured from light-duty vehicles and heavy-duty engines. These emission levels were used in air quality dispersion models to predict the resultant air quality levels. The ambient concentrations predicted for each pollutant were then compared to suggested concentrations at which adverse health effects may be found to determine if additional monitoring or control would be indicated for these pollutants. It was determined that mobile source emissions of sulfuric acid, hydrogen cyanide, and ammonia do not in general result in ambient levels of concern for the air quality situations studied.

The advent of emission control technology has resulted in significant changes in both the total mass and detailed patterns of hydrocarbons emitted from automobiles. Emission rates of 56 hydrocarbons from 22 motor vehicles, including catalyst and noncatalyst configurations, were determined for the Federal Urban Driving Cycle. An increased relative abundance of methane is indicated for vehicles equipped with oxidation catalysts. In view of the photochemically non-reactive nature of methane, simple and economic procedures for determination of vehicle nonmethane hydrocarbon emission rates are evaluated. In general the procedures evaluated require independent total hydrocarbon and methane analysis, with the nonmethane hydrocarbon level calculated by difference. The procedures are evaluated by comparison of indicated nonmethane hydrocarbon emission rates with rates obtained by summation of individual compound rates determined by advanced gas chromatographic procedures.

A simple, inexpensive, critical flow blender has been developed for filling a tedlar bag with controllable concentrations of HC, NOx, CO2, and CO gases at levels encountered in automobile emissions testing. According to a daily schedule, a technician takes the bag to all analyzer sites in the laboratory for analysis. The concentrations indicated by each site are compared to the overall averages. The results are stored in a computerized data base from which control charts, statistical analyses, and interpretations of significant differences among test sites can be made. The precision, accuracy, and statistical interpretations of the data are discussed.

An experimental program was conducted to characterize the gaseous and particulate emissions from a 1975 Peugeot 504D light duty diesel-powered vehicle. The vehicle was tested over the 1975 Federal Test Procedure, Highway Fuel Economy Test, and Sulfate Emissions Test driving cycles using four different fuels covering a fair range of composition, density, and sulfur content. In addition to fuel economy and regulated gaseous emission measurements of hydrocarbons, carbon monoxide, and oxides of nitrogen, emission measurements were also obtained for non-regulated pollutants including sulfur dioxide, sulfates, aldehydes, benzo[a]pyrene, carbonyl sulfide, hydrogen cyanide, nonreactive hydrocarbons, and particulate matter. The results are discussed in terms of emission trends due to either fuel type or driving cycle influence.