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Control and elimination of mobil-source particulate matter (PM) emissions is of increasing interest to engineers and scientists as regulators in industrialized countries promulgate lower emission levels in diesel engines. Relative to their gasoline engine counterparts, today's diesel engines, in general, still emit a higher mass of PM. While strictly speaking, this PM is an agglomeration of organic and inorganic particles, the predominant component is carbon and is commonly referred to as “soot”. For mobil-source PM control, one of the current preferred technologies is the ceramic closed-cell monolith Diesel Particulate Filter (DPF). Ideally, DPFs accumulate and store PM during low speed/temperature engine operation and burn the accumulated PM during high speed/temperature operation.

The effects of fuel composition and engine operating parameters on high-pressure, direct injection gasoline (DIG) injector plugging and deposit formation have been studied. The engine used was a conventional dual-sparkplug, 2.2-liter Nissan engine modified for direct injection using one of the spark plug holes. The engine was run under 20% rich conditions to accelerate deposit formation. A ten-fuel test matrix was designed around T90, sulfur level, and olefin levels indicated in the European gasoline specifications for year 2000. The gasolines, containing no detergents, were formulated using refinery stream blends to match the specified targets. Injector flow loss was monitored by fuel flow to the engine and monitoring oxygen sensors on each of the four cylinders. The impact of fuel composition on deposit formation and injector plugging is discussed. Injector flow loss was strongly influenced by injector tip temperature.

This paper presents the findings of some fundamental characterisation of the deposits that form on the injectors of an air-assisted DISI automotive engine, including the effect of these deposits on engine performance when operated in different combustion modes, with varying fuel composition and additive content. A root cause analysis was undertaken, including an assessment of injector temperature and deposit chemistry. Fuels from a matrix designed around the European year 2000 gasoline specifications for T90, olefin and aromatic levels were used to study the effect of fuel composition on deposit formation. Two commercial gasoline detergent additives, of different chemistries, were used to investigate the impact on deposit formation. The results of the fuels study and deposit analysis are consistent with published theories concerning fuel composition impact on combustion chamber deposit (CCD).

Extensive vehicle fleet testing has demonstrated that use of MMT can reduce net tailpipe out emissions. The use of fuel containing the octane-enhancing, emission-reducing fuel additive leads to manganese oxide deposits in the vehicle exhaust system. Studies of the physical and chemical effects of manganese oxide deposits on the performance of catalytic converters conclusively demonstrated that MMT does not adversely affect catalytic converters and, in fact, protected the converters from phosphorus and zinc. Despite the overwhelming evidence that MMT is compatible with catalytic converters and vehicle emission control systems, concerns have recently been raised about the effect of manganese oxides on OBD-II catalytic converter monitoring.

This paper describes a method for accurately measuring sulfur oxides in automotive exhaust. In this method, the exhaust from a car is diluted with ambient air, then introduced into a large bag filled with clean dry air. The temperature, pressure, and humidity of the diluted exhaust are measured, along with the concentrations of hydrocarbons, carbon monoxide, carbon dioxide, SO2, and sulfates. Bag concentrations are related to the exhaust by using the sulfur/carbon ratio of the fuel. Established instrumental methods are used for the carbon compounds. The sulfur dioxide in the diluted exhaust gas is measured by the West-Gaeke method, which involves collecting a gaseous sample in a scrubber containing potassium tetrachloromecurate. The sulfates are collected on a particulate filter and measured by a new colorimetric method. The techniques we have developed have been applied to both non-catalyst and catalyst-equipped cars. These studies have shown that: 1.

The Clean Air Act of 1990 requires on-board diagnostics (OED) capabilities on all new vehicles. These diagnostic systems monitor the performance of engine and emission system components and inform the vehicle operator when component or system degradation could significantly impact emissions. Acceptable operation of the monitor requires proper treatment of system variables. Fuel composition is one of many possible variables that must be considered for monitoring components directly in the exhaust stream. Recently, the octane enhancing, emissions reducing additive methylcyclopentadienyl manganese tricarbonyl (MMT) was reintroduced into unleaded gasoline in the U.S. Prior to reintroduction, the additive underwent extensive testing to demonstrate that use of MMT does not adversely affect vehicle emissions or the operation of emission systems such as OBD. However, questions have been raised about the influence of the additive on OBD systems.

Several makes and models of cars were modified for lean-burn operation using the Turbulent Flow Manifold (TFM), a unique intake manifold that provides improved preparation and distribution of the fuel-air mixture. Operation of the TFM is described, and exhaust emissions and fuel economy data are presented for the various cars. Exhaust port liners and thermal reactors were shown to be effective devices for reducing emissions from the basic lean-burn system. One car equipped with the TFM, port liners, and reactors was operated for 50,000 miles on an EPA-type durability test and had emissions well below the 1975 standards for California. Emissions, fuel economy, and durability data are presented.

Emissions regulations for 2007 will likely require engine manufacturers to use a diesel particulate filter (DPF) to meet particulate matter (PM) emission requirements. With the lower operating temperatures of light-duty diesel engines, some form of catalyst will be required to facilitate oxidation of accumulated soot PM to regenerate the DPF. This catalyst can either be permanently applied to the filter substrate in the manufacturing process, or be continuously delivered via the diesel fuel. In this study we examined the impact of using both forms of catalyst. A recently published study of the fuel-borne catalyst additive MMT [1] (Methylcyclopentadienyl Manganese Tricarbonyl), reviewed the performance of MMT in conjunction with an uncatalyzed DPF [2].

Additive control of DIG injector coking was investigated on two dynamometer-operated engines and validated in a vehicle. The first engine was a Nissan research “mule” engine designed to severely coke the injectors so that additive effect could be more easily discriminated. Initial additive screening and optimization was carried out in this engine and a few chosen candidates of the Mannich chemistry-type were further optimized in the second engine, and in a vehicle. The second engine, which was also dynamometer operated, was an advanced wall-guided design capable of both homogeneous and stratified operation. On this engine we were able to optimize the Mannich additive “Man C-2” separately in two different carrier systems to show a carrier effect, and by manipulating the purity of the base detergent Man C-2 to show a detergent activity modulation by trace co-products.

The temporal and spatial evolution of the ignition and premixed-burn phases of a direct-injection (DI) diesel spray were investigated under quiescent conditions. The diagnostics used included temporally resolved measurements of natural light emission and pressure, and spatially resolved images of natural light emission. Temporally resolved natural light emission measurements were made with a photo-multiplier tube and a photodiode, while the images were acquired with an intensified CCD camera. The experiments were conducted in an optically accessible, constant-volume combustion vessel over a range of ambient gas temperatures and densities: 800-1100 K and 7.3-45.0 kg/m3. The fuel used was a ternary blend of single-component fuels representative of diesel fuel with a cetane number of 45. The fuel was injected with a common-rail injector at high pressure (140 MPa). The results provide new information on the evolution of the two-stage ignition/premixed-burn phases of DI diesel sprays.

Automotive gear oil development has expanded beyond the historical requirements of emphasizing wear protection to encompass modern needs for fuel economy and limited slip frictional properties. This paper describes the development process of a new generation, fuel efficient gear lubricant for use in light duty vehicles. A systematic formulation approach was used, encompassing fluid viscometrics and additive optimization. Performance testing in both laboratory and vehicle tests is described. Though standard GL-5 tests were used to confirm oxidation, wear and corrosion performance, emphasis is given to those methods used for optimizing fuel economy.

In designing fuel economy oils, two useful approaches are reduction of viscosity and incorporation of friction reducers. To achieve viscosity reduction without incurring problems of high oil consumption and possible interference with catalyst or oxygen sensor performance, the use of part-synthetic lubricants can be helpful. In this way, oil volatility (therefore oil consumption) is reduced and fuel economy is improved without incurring engine operating penalties. Friction reducers also can be used to improve fuel economy. The combination of these approaches furnishes the benefits of both. Laboratory and road testing of such combinations show important fuel economy benefits in normal vehicle operation, greater than those achievable from either approach alone. In addition, all other engine performance requirements are completely met. This advance in engine oil formulation technology, which opens up new possibilities to both vehicle manufacturers and consumers, is being further pursued.

This paper presents the results of an investigation cooperatively undertaken by Esso Research and Engineering Company and Ethyl Corporation to determine whether the hydrocarbon-type effect observed in road antiknock studies of gasolines is independent of other fuel properties over and above laboratory octane numbers. For this study, 51 finished gasolines were carefully blended from 57 base stock components to provide controlled levels of those major fuel properties which affect road performance. The controlled properties were Research octane number, sensitivity (RON minus MON), ratio of aromatics to olefins, tetraethyllead content, octane-number distribution in the fuel's boiling range, boiling-range location of the unsaturated hydrocarbons, and sulfur content. A unique feature of the blending scheme was the formulation of blend pairs, in which all but one of the major fuel properties were essentially equal.

This oil category was driven by two new cooled exhaust gas recirculation (EGR) engine tests operating with 15% EGR, with used oil soot levels at the end of the test ranging from 6 to 9%. These tests are the Mack T-10 and Cummins M11 EGR, which address ring, cylinder liner, bearing, and valve train wear; filter plugging, and sludge. In addition to these two new EGR tests, there is a Caterpillar single-cylinder test without EGR which measures piston deposits and oil consumption control using an articulated piston. This test is called the Caterpillar 1R and is included in the existing Global DHD-1 specification. In total, the API CI-4 category includes eight fired-engine tests and seven bench tests covering all the engine oil parameters. The new bench tests include a seal compatibility test for fresh oils and a low temperature pumpability test for used oils containing 5% soot. This paper provides a review of the all the tests, matrix results, and limits for this new oil category.

MMT (methylcyclopentadienyl manganese tricarbonyl) is an antiknock additive for unleaded gasoline, which is now required for cars equipped with catalytic converters. Because of its effectiveness, MMT is economically attractive compared with achieving antiknock quality by refinery processing. Use of MMT in gasoline at a concentration of 0.125 g of contained manganese per gallon provides, on the average, about 2 road octane numbers. Compared to processing, this could represent a savings in crude oil of about 1%. Like other antiknocks, the economic attractiveness of MMT is greatest at low concentrations. Extensive road and dynamometer engine tests have shown that use of MMT in the recommended concentration range is compatible with general aspects of car operation--octane number requirement, exhaust valve and spark plug durability, and exhaust gas recycle for NOx control. Moreover, beneficial effects in exhaust valve guide and seat wear have been observed with MMT in some tests.

The long-term durability of a vehicle's exhaust catalyst is essential for emission control. Catalyst durability can be affected by a variety of factors including engine oil consumption. During normal engine operation, some of the lubricating oil is combusted. The deposition of combustion products from phosphorus containing lubricant additives on the catalyst can adversely affect catalyst durability. In an attempt to minimize the impact of oil consumption on additive performance, engines have been designed to reduce oil consumption and oils are being formulated with lower concentrations of phosphorus compounds. However, these phosphorus compounds protect the engine from excessive wear and cannot be easily removed from lubricant oil due to concerns over engine durability. The use of a phosphorus scavenger is an approach that works together with engine design to minimize catalyst deterioration.

SAE Paper 2002-01-2894 entitled, “The Impact of MMT Gasoline Additive on Exhaust Emissions and Fuel Economy of Low Emission Vehicles (LEV)” presents discussion and conclusions concerning the emissions from vehicles that accumulated mileage on gasoline with and without the fuel additive, methylcyclopentadienyl manganese tricarbonyl (or MMT®). Although the authors of the paper express concern about use of MMT®, the data on which the authors rely are consistent with the results and conclusions from prior evaluations of MMT® which have found that MMT® is compatible with effective emission control system operation (1,2,3). All vehicles tested in the study met the emission standards for all pollutants that apply to the test vehicles in-use and analysis of the data show MMT® had no effect on fuel economy.