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This paper describes the results of a study that examined the mechanism of phased perturbation as an emissions control technique. Phased perturbation involves independently controlling the fuel delivered to each bank of a dual bank engine (or each cylinder of a single manifold engine), which allows the two banks to have an adjustable, relative Air/Fuel (A/F) perturbation phase-shift from one another. The phase shifted exhaust is then recombined to achieve a near stoichiometric mixture prior to entering a single underbody catalyst. Phase shifting the exhaust Air/Fuel ratio creates a situation in which both rich exhaust constituents (unburnt hydrocarbons and carbon monoxide) and lean exhaust constituents (oxygen and oxides of nitrogen) arrive at the catalyst at the same time. The results of the study showed that phased perturbation produced a significant effect on A/F control and catalyst THC, CO, and NOx efficiency.

Increasing fuel costs and the desire for reduced dependence on foreign oil have brought the diesel engine to the forefront of future medium-duty vehicle applications in the United States due to its higher thermal efficiency and superior durability. One of the obstacles to the increased use of diesel engines in this platform is the Tier 2 emission standards. In order to succeed, diesel vehicles must comply with emissions standards while maintaining their excellent fuel economy. The availability of technologies-such as common rail fuel injection systems, low-sulfur diesel fuel, oxides of nitrogen (NOX) adsorber catalysts or NACs, and diesel particle filters (DPFs)-allows for the development of powertrain systems that have the potential to comply with these future requirements. In support of this, the U.S. Department of Energy (DOE) has engaged in several test projects under the Advanced Petroleum Based Fuels-Diesel Emission Control (APBF-DEC) activity [1, 2, 3, 4, 5].

A computer controlled system capable of intercepting and performing closed-loop control of a vehicle subsystem during targeted modes of operation was developed. The system has been given the acronym ERIC, for Emissions Reduction Intercept and Control system. This study was prompted by the need for the ability to modify engine controls through targeted modes of operation, without altering the majority of engine operation, to assist in the integration of exhaust aftertreatment and engine systems. The general concept and approach for applying the ERIC method, and application of the system to perform targeted, mode-activated EGR control intercept on a 1997 Ford Crown Victoria, are described in this paper. Data are presented that demonstrate how the problem mode was identified, targeted, mapped, and modified. FTP-75 test data are presented to show the impact of this particular application.

The classical approach to prepare engine exhaust emissions control systems for evaluation and certification is to condition the fresh parts by aging the systems on an engine/dynamometer aging stand. For diesel systems this can be a very lengthy process since the estimated service life of the emissions control systems can be several hundred thousand miles. Thus full useful life aging can take thousands of engine bench aging hours, even at elevated temperatures, making aging a considerable cost and time investment. Compared to gasoline engines, diesel engines operate with very low exhaust gas temperatures. One of the major sources of catalyst deactivation is exposure to high temperature [ 1 ].

Increasing fuel costs and the desire for reduced dependence on foreign oil has brought the diesel engine to the forefront of future medium-duty vehicle applications in the United States due to its higher thermal efficiency and superior durability. The main obstacle to the increased use of diesel engines in this platform is the upcoming extremely stringent, Tier 2 emission standard. In order to succeed, diesel vehicles must comply with emissions standards while maintaining their excellent fuel economy. The availability of technologies such as common rail fuel injection 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 these future requirements. In meeting the Tier 2 emissions standards, the heavy light-duty trucks (HLDTs) and medium-duty passenger vehicles (MDPVs) will face the greatest technological challenges. In support of this, the U.S.