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Future European air quality standards for light duty diesel vehicles will include stringent NOx emission regulations. In order to meet these regulations, a lean NOx catalyst system may be necessary. Since the catalytic removal of NOx is very difficult with the large concentration of oxygen present in diesel exhaust, a reductant is usually added to the exhaust to increase the NOx conversion. This paper describes a lean NOx catalyst system for a Transit light-duty truck which uses a reductant solution of urea in water. In this work, a microprocessor was used to vary the amount of the reductant injected depending on the operating conditions of a 2,5 L naturally aspirated HSDI engine. The NOx conversions were 60% and 80% on the current European driving cycle and the U.S. FTP cycles, respectively. Data on the emissions of HC, CO, NOx, particulate mass and composition, individual HC species, aldehydes, PAH and most HC species were evaluated.

Regulated and non-regulated emissions from five current European diesel passenger cars and one light-duty diesel truck were measured to assess the environmental impact of diesel vehicles and to help determine the emission characteristics of the two types of combustion systems: indirect injection (IDI) and high speed direct injection (HSDI). The vehicle emissions were measured using the European Motor Vehicle Emissions Group (MVEG) cycle and the U.S. Federal (FTP 75) test procedures. Measured emissions included HC, CO, NOx and particulate mass (PM), C1 to C12 hydrocarbon species (here called light hydrocarbon or LHC), aldehydes, particulate composition and particle size distribution. The particulate composition measurements included soluble organic fraction (SOF), its oil and fuel sub-fractions, and the sulfate fraction. All passenger cars and the light-duty commercial vehicle tested complied with the current European Emissions Directive 91/441/EEC.

The regulated and non-regulated emissions of a current diesel passenger car and two light-duty diesel trucks with catalysts and particulate traps were measured to better understand the effects of aftertreatment devises on the environment. The passenger car, a 1.8 L IDI TC Sierra, was tested both with and without three different diesel oxidation catalysts (DOC) and with two fuel sulfur levels, 0 and 0.05 wt%. One light-duty truck, a 2.5 L DI NA Transit, was tested on one fuel, 0.05 wt% sulfur, with and without three different particulate trap/regeneration systems and with and without a urea lean NOx catalyst (LNC) system. A second similar Transit was tested on the 0.05 wt% sulfur fuel with an electrically regenerated trap system. The results are compared to each other, regulated emission standards, and to emissions from gasoline vehicles.

Vehicle emissions have been measured and the results statistically evaluated for a vehicle test fleet consisting of four Escorts and four Explorers using both a fully formulated durability fuel doped with methylcyclopentadienyl manganese tricarbonyl (MMT) at 1/32 gram Mn/gallon and the same fully formulated durability fuel without the MMT. The fleet was divided in half -- half with MMT and half without MMT doped fuel. This report covers emission measurement results at 5,000; 15,000; 50,000 and 100,000 miles of exposure to MMT doped fuel. A modified paired t-test is used to analyze the emission data obtained from all the fleet vehicles. The statistical evaluation of both feedgas and tailpipe emissions indicate that the use of MMT is detrimental to emissions of HC at the 15,000 mile; 50,000 mile and 100,000 mile levels of MMT exposure. As mileage is accumulated, the pronounced the effect on HC by the fuel additive MMT.