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With the wider use of Direct Injection Spark Ignition (DISI) vehicles in the marketplace, a program was conducted to develop a short-duration fuel injector fouling test. Once a specific driving cycle and base fuel combination was found to produce a significant increase in Long Term Fuel Trim (LTFT), several Deposit Control Additive (DCA) technologies were evaluated for their ability to keep the direct gasoline injectors clean. The increase in LTFT is indicative of fuel injector fouling and a corresponding decrease in flow through them. The test vehicles for this program were a 2008 General Motors Pontiac Solstice GXP equipped with a DISI 2.0 liter turbocharged I-4 and a 2008 Audi A4 equipped with a DISI 3.2 liter V-6 engine. A proprietary base fuel formulated to mimic a U.S. EPA 65th percentile fuel was tested to assess its deposit forming tendencies.

With the wider use of biofuels in the marketplace, a program was conducted to study the deposit forming tendencies and performance of E85 (85% denatured ethanol and 15% gasoline) in a modern Flexible Fuel Vehicle (FFV). The test vehicle for this program was a 2006 General Motors Chevrolet Impala FFV equipped with a 3.5 liter V-6 powertrain. A series of 5,000 mile Chassis Dynamometer (CD) Intake Valve Deposits (IVD) and performance tests were conducted while operating the FFV on conventional (E0) regular unleaded gasoline and E85 to determine the deposit forming tendencies of both fuels. E85 test fuels were found to generate significantly higher levels of IVD than would have been predicted from the base gasoline component alone. The effects on the weight and composition of IVD due to a corrosion inhibitor and sulfates that were indigenous to one of the ethanols were also studied.

General Motors plans to introduce a hybrid version of its popular light-duty full-size (Silverado/Sierra) pickup truck. Primary emphasis of the hybrid propulsion system for this truck is on maximizing fuel savings at minimum cost and without sacrificing performance or driveability. The hybrid powertrain features a novel, compact method of integrating an electric motor/generator between the largely unchanged engine and transmission. Extensive energy analysis and several unique control strategies are being used to meet the vehicle's performance, driveability, and emissions objectives. This paper will focus mainly on the powertrain integration and on powertrain controls for the hybrid propulsion system.

General Motors plans to introduce a hybrid version of its popular light-duty full-size (Silverado/Sierra) pickup truck. The program imperative of minimal vehicle architecture change drove a highly integrated powertrain solution. The hybrid powertrain features a novel, compact method of integrating an electric motor/generator between the largely unchanged engine and transmission, preserving their locations. From the targeted hybrid functions, power and energy specifications are derived. Specific design aspects and performance examples relating to the motor/generator packaging, torque converter, and overall vehicle driveabiltiy are discussed.

The E-35 “Running Loss” program was planned in the fall of 1996, and conducted in the summer of 1997, as the third part of a series of Coordinating Research Council (CRC) sponsored evaporative emission test programs. One hundred and fifty vehicles (half cars - half light duty trucks) were recruited at a local I/M lane, and tested for running loss emissions at the ATL Facility in Mesa, AZ. The previous CRC programs had studied hot soak, and then diurnal emissions. Running loss emissions were measured in a Running Loss SHED (RL-SHED) for a 25 minute, 7.5 mile trip on a hot summer day (95°F). Vehicles from model years 1971 through 1991 were tested. A wide range in emission levels was observed - from a low of 0.13 g/mile to 43 g/mile. The test results were not able to establish whether car emissions are different, or the same, as light duty trucks. The major causes of the high emissions were liquid leaks on carburetor equipped models.