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Electronic Control Module (ECM)
A microprocessor that determines the beginning and end of each injection cycle on every cylinder. The ECM determines both fuel metering and injection timing in response to such parameters as engine crankshaft position and rpm, engine coolant and intake air temperature, and absolute intake air boost pressure.
Elemental Carbon (EC)
Inorganic carbon, as opposed to carbon in organic compounds, sometimes used as a surrogate measure for diesel particulate matter, especially in occupational health environments. Elemental carbon usually accounts for 40-60% of the total DPM mass.
Emission Credit Trading
A program administered by the Environmental Protection Agency under which low polluters are awarded credits which may be traded on a regulated market and purchased by polluters who are in noncompliance for emissions until compliance can be achieved.
EPACT
The U.S. Energy Policy Act of 1992.
EV
Electric vehicle.
Evaporative Emissions
Hydrocarbon vapors that escape from a fuel storage tank or a vehicle fuel tank or vehicle fuel system.
Federal Test Procedure (FTP)
Test cycle(s) used in the U.S. for emission testing and certification of engines and vehicles. The chassis dynamometer cycle for light duty vehicle testing is commonly referred to as FTP-75. The engine dynamometer cycle for testing of heavy-duty (HD) engines is known as HD FTP, or FTP Transient cycle.
Flash Point
The temperature at which a combustible liquid gives off just enough vapor to produce a vapor/air mixture that will ignite when a flame is applied. The flash point is measured in a standardized apparatus using standard test methods, such as ASTM D93 or ISO 2719.
Flexible-Fueled Vehicle
A vehicle with the ability to operate on alternative fuels, 100 percent petroleum-based fuels, or a mixture of alternative fuel and petroleum-based fuels.
Fossil Fuel
Any naturally occurring organic fuel formed in the Earth’s crust, such as petroleum, coal and natural gas.
Fuel cycle
The processes involved in extracting a fuel in its native form, converting it to a useful product, transporting it to market, and consuming it at its final destination.
Gas Turbine
A turbine powered by a gas, such as the hot gas produced in combustion processes.
Gas Turbine Engine
A combustion engine utilizing a turbine, such as a jet engine.
Genset
Generator set, a generating system comprising a combustion engine driving an electrical generator.
Geometric Surface Area (GSA)
In monolith catalyst substrates, the total channel surface area per unit of substrate volume.
Gross Vehicle Weight (GVW)
The maximum loaded weight (including the vehicle itself, passengers, and cargo) for which a vehicle is designed, as specified by the manufacturer. Often used as a criterion of vehicle size for the purpose of legislation; the exact definition may vary depending on the jurisdiction.
Hybrid Electric Vehicle (HEV)
Hybrid-electric vehicle. Various types of electric vehicles that use another power source to propel the vehicle or generate power for an electric drive train, or a combination of the two types.
Hydraulic/Electronic Unit Injector (HEUI)
A type of unit injector actuated by engine oil pressure rather than the camshaft. A very high oil pressure (up to 3,000 psi) is created by a separate oil pump. This high pressure is routed to every injector through a gallery. The engine’s Electronic Control Module varies the pressure in response to engine speed and other parameters.
Hydromechanical Injection
An injection system in which mechanical parts work through hydraulic pressure to meter and time the injection of fuel. No electronics are incorporated into hydromechanical injection systems.
Ignition Delay
The length of time or number of degrees of crankshaft rotation between the beginning of injection and ignition of the fuel.
In-Direct Injection (IDI)
In diesel engines with in-direct injection the fuel is injected to an auxiliary pre-chamber. Combustion starts in the prechamber and propagates to the cylinder.
Inherently Low Emission Vehicle (ILEV)
Any vehicle that is certified to meet transitional low-emission vehicle standards established by the California Air Resources Board (CARB) and does not emit any evaporative emissions.
Injection Period
The time, measured in degrees of crankshaft rotation, between the beginning and end of injection. On engines with hydromechanical injection systems, it is controlled by the opening and closing of ports in the injector body or by the action of a plunger forcing fuel out of a cup. On electronic injection systems, it is determined directly or indirectly by the action of a solenoid valve.
In-Line Injection Pump
An injection pump with a separate cylinder and plunger for each engine cylinder. Each plunger is rotated by a rack to determine metering via ports in the body of the pump and helical cuts on the pump plungers. The plungers are driven off a camshaft, which usually incorporates a centrifugal or electronically controlled timing advance mechanism.
Inspection and Maintenance Programs (IM)
In-use emission testing programs, primarily for passenger cars, used by some U.S. states to identify vehicles that cause excessive emissions which contribute to air pollution.
Intumescent Mat
Ceramic fiber mat which irreversibly expands after exposed to high temperature. Usually contains vermiculite. Intumescent mats are used in the canning of catalytic converters and diesel filters to hold the ceramic substrate inside the steel canister.
In-Use Deterioration (IUD)
The effect of time and use on vehicle performance and emissions.

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