2003 Model Year Summary
- Application in Saturn ION
- Fuel System for Chevrolet Cavalier and Pontiac Sunfire
- Bi-fuel for Chevrolet Cavalier
- Air Injection Reaction (AIR) deleted from Saturn LS Automatic
- New assembly plant in Spring Hill, Tenn.
FULL DESCRIPTIONS OF NEW OR CHANGED FEATURES
FUEL SYSTEM FOR CHEVROLET CAVALIER AND PONTIAC SUNFIRE
The new fuel system of the fuel system on the Ecotec 2.2-liter (L61) is essentially the same in design and function, with Multec II fuel injectors, from the previous version. It continues to manage fuel pressure with a return line that bleeds excess fuel back to the gas tank. The new system does add insulators around each injector that reduce conductive heat transfer from the cylinder head, much like those used on the returnless fuel system in the ION and VUE.
For 2003, the Ecotec 2.2-liter is standard in gasoline-powered Cavaliers and Sunfires. It was optional in these applications for 2002.
APPLICATION IN SATURN ION
The Ecotec 2.2-liter (L61) powers the 2003 Saturn ION sedan and coupe. For this application, it is configured as it is in the Saturn VUE sport-utility vehicle, with one significant difference -- in place of the VUE’s electronic throttle control (ETC), the ION has a mechanically operated throttle. The ION shares the low-profile mechanical throttle body used in the Chevrolet Cavalier and Pontiac Sunfire and Grand Am, which in turn is different from the throttle body used for the Saturn L-Series. Throttle diameter is the same in both cases, but the low-profile version is fitted more closely to the engine for packaging in ION, Cavalier, Sunfire and Grand Am.
Like the VUE variant, the ION's 2.2-liter engine has a higher compression ratio and more aggressive cam profiles than the variant used in the Saturn L-Series. The higher compression (10.0:1 compared to 9.5:1 in the Saturn L-Series) is a function of flat-top pistons. Where the engine in the Saturn L-Series has a slight dish in the piston dome (approximately 2 mm deep), pistons in the ION and VUE variants are flat. The cam lobe profiles in the ION/VUE engines are also different from those in the Saturn L-Series. Maximum valve lift and duration are essentially the same in all of the engines, but the ramp--up rate--the speed at which the valves reach maximum lift--is higher in the ION and VUE version. The net result is more horsepower and torque (see product specifications).
Several other features distinguish the ION and VUE engine from other North American applications. The fuel–delivery system on the other applications has a return line from the fuel injectors that manages fuel pressure by bleeding off excess fuel and returning it to the tank. Fuel delivery in all 2.2-liter engines is essentially the same up to the fuel injector. The 2.2-liter engines in the ION and VUE have no return line. These variants use an electric pressure regulator to manage fuel pressure. Injectors on the returnless system have an insulator the reduces conductive heat transfer from the cylinder head.
The Ecotec 2.2-liter in the ION and VUE has an electric power steering pump, rather than a hydraulic pump driven by a cam gear. Because the pump is operated by electricity from the vehicle’s charging system, there is no parasitic power loss operating the power steering, and fuel economy is improved. The ION and VUE have a plate over the cam cover where the power steering pump would otherwise mount. The ION and VUE variant also has a different flex plate (the mating surface between engine and transmission) to accommodate the VTi variable transmission, which is offered as an option on both. The flex plate has a unique bolt pattern.
The ION and VUE engines also differ from other North American applications in their use of a separate engine control module (ECM) and transmission control module (TCM) rather than an integrated powertrain control module (PCM). While the ECM/TCM concept is the same with the ION and VUE engines, the hardware is actually different with each variant. On the ION, the ECM is chassis-mounted under the hood to the right of the engine, rather than engine-mounted on the intake manifold.
Finally, the VUE and ION 2.2-liter engines have a close-coupled catalytic converter. The converter is mounted closer to the exhaust manifold than it is in other Ecotec 2.2-liter (L61) equipped vehicles. It heats more quickly because of its proximity to the exhaust manifold, and achieves light off--the temperature at which exhaust emissions are most efficiently oxidized--more quickly.
NEW ASSEMBLY PLANT IN SPRING HILL, TENN.
The Ecotec 2.2-liter (L61) is currently built in two assembly plants (Tonawanda, N.Y. and Kaiserlautern, Germany). A third facility in Spring Hill, Tenn., is scheduled to open in 2002.
BI-FUEL FOR CHEVROLET CAVALIER
The new bi-fuel Ecotec 2.2-liter (L42) operates on either gasoline or compressed natural gas (CNG). The bi-fuel 2.2-liter is an option in the Chevrolet Cavalier for Federal Clean Fuel Fleet service. It is expected to be used primarily in fleet service and replaces the CNG variant of the 2.2-liter (LN2) four-cylinder.
Compressed natural gas is the 2.2-liter (L42) engine's primary fuel. It uses CNG as long as there is sufficient pressure in the storage tank. If pressure drops below a prescribed level, the engine automatically switches to gasoline operation. The change occurs without driver intervention and is indicated only by a ``gasoline operation’’ light in the instrument panel. The driver cannot manually override CNG operation.
Hardware differences between the 2.2-liter (L61) and 2.2-liter (L42) are entirely in the cylinder head and fuel delivery system. CNG does not have the lubricating properties of liquid gasoline, and it tends to produce more surface erosion than gasoline as it flows into the combustion chambers. To ensure maximum durability with CNG operation, the engine has unique valve seats and intake valves that are more resistant to erosion. The seats are manufactured from an alloy called Brico 3010, a sintered powder metal with higher chromium, tungsten and copper content than the alloy used for the regular gas version's valve seats. The engine's intake valves are forged from a premium alloy that includes tungsten, vanadium, manganese, and silicone, and has more chromium than conventional iron-alloy valve material. These alloys virtually eliminate the possibility of valve face and seat erosion with CNG operation.
Fuel-delivery systems on the 2.2-liter (L61) and 2.2-liter-CNG (L42) are substantially different. The CNG engine actually has two fuel systems in one, with sequential port injection for CNG running parallel with the multipoint gasoline injection.
The CNG injection has its own stainless steel fuel rail and uses an adaptor plate, molded from the same nylon composite as the intake manifold, installed between the manifold and the cylinder head. The plate is 8 millimeter thick, with a boss and narrow passage molded at each intake port. The CNG injectors mount on the bosses, roughly one inch to the left of the standard Multec II gasoline injectors, and deliver CNG through the passage in the adaptor plate to the port. The natural gas injectors are fired sequentially. The engine adds a second injector driver module (IDM) to manage the injectors. This solid-state device controls the CNG injector pulses electronically.
To manage the second IDM, the engine has a unique powertrain control module (PCM). The PCM uses software developed specifically for bi-fuel operation.
Maximum fuel delivery pressure in both of the fuel systems is the same: about 65 psi, with a normal operating range of 40-45 psi. Nonetheless, the CNG is stored at tremendous pressure up to 3600 psi. The CNG tank is installed in the Cavalier’s trunk, over a high-pressure regulator that reduces gas pressure to 170 PSI and sends the fuel through a line under the car. A second intermediate pressure regulator mounted on the transmission further reduces fuel pressure to about 45 psi for delivery to the injectors. Two electrically operated shut-off valves--one on the tank, the other under the hood--can shut down the CNG fuel system if the on-board diagnostics detect the slightest malfunction. In such circumstances, the PCM switches the 2.2-liter to gasoline operation and advises the driver of the problem with a ``service engine’’ warning light in the dash.
The Cavalier’s CNG tank has a capacity of 6.2 GGE (gasoline gallon equivalent). At full capacity, the tank stores the same amount of energy, measured by BTUs, as 6.2 gallons of gasoline. The bi-fuel engine is expected to extend the Cavalier’s range 150-200 miles over the dedicated gasoline vehicle. CNG operation reduces the engine's maximum horsepower and torque approximately 10 percent (see product specifications).
AIR INJECTION REACTION (AIR) DELETED FROM SATURN LS AUTOMATIC.
The AIR system has been removed from Saturn L-Series sedans equipped with the 2.2-liter (L61) and an automatic transmission. AIR was used to lower exhaust emissions by injecting warm, fresh air into the combustion process to create an exothermic reaction. The reaction creates heat and warms the catalytic converters more quickly, speeding catalyst light off and reducing emissions during cold starts--a critical phase in certification tests. The automatic-equipped L-Series now meets all government emissions standards without AIR. Removing AIR reduces cost and mass.
Saturn L-Series sedans equipped with a manual transmission continue with AIR.
Often referred to as GM's first global engine, the Ecotec 2.2 L (L61) has leveraged GM's worldwide design and engineering capability by drawing on the best practices of technical centers in North America and Europe. The engine has created a template for subsequent global powertrain development. Most important, it is a world-class gasoline engine with obvious benefits for the customer. At 305 pounds fully dressed, the engine is the lightest engine GM has produced in its displacement class, and one of the most compact four-cylinders in the world.
The engine architecture has a displacement range capability of 1.8 to 2.4 liters, single or dual overhead cams, turbocharging and a broad range of peak power outputs. It can be used in virtually all front-drive passenger cars, from the lower end of the price spectrum to premium, upmarket applications. It gives GM a stronger presence in one of the industry's largest volume, most competitive displacement classes. The engine has undergone the most rigorous test and validation process of any engine in GM history, according to the development team. Its manufacturing process allows greater precision and efficiency compared to GM's other four-cylinder engines.
For the customer, the Ecotec 2.2-liter engine delivers performance, efficiency, low maintenance and smooth operation with technology familiar in premium V engines, including all-aluminum construction, hydraulic roller finger valve operation and electronic “drive-by-wire”' throttle. For GM, this engine delivers manufacturing economies, maximum flexibility and broad application.