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Ethanol: Grain alcohol (C
2
H
5
OH), generally pro-
duced by fermenting starch or sugar.
Evaporative Emissions Controls: An automotive
emission control system designed to reduce hy-
drocarbon emissions by trapping evaporated fuel
vapors from the fuel system.
Excess Flow Valve: A check valve that is caused
to close by the fuel when the flow exceeds a pre-
determined rate.
FTV: Fuel Trim Valve.
FFV: Flexible Fuel Vehicle.
Firing Line: The portion of an oscilloscope pattern
that represents the total amount of voltage being
expended through the secondary circuit.
FMVSS: Federal Motor Vehicle Safety Standards.
FPP: Foot Pedal Position Sensor
Fuel Injector: a spring loaded, electromagnetic
valve which delivers fuel into the intake manifold,
in response to an electrical input from the control
module.
Fuel Lock: A solenoid-controlled valve located in
the fuel line to stop the flow when the engine
stops or the ignition switch is off.
Gasohol: 10 percent ethanol, 90 percent gasoline.
Often referred to as E-10.
Gasoline: A motor vehicle fuel that is a complex
blend of hydrocarbons and additives. Typical oc-
tane level is 89.
GCP: Spectrum III (90-pin) ECM.
Greenhouse Effect: A scientific theory suggesting
that carbon dioxide from the burning of fossil fuels
is causing the atmosphere to trap heat and cause
global warming.
HC: Hydrocarbon. An organic chemical compound.
HD 10: A fuel of not less than 80% liquid volume
propane and not more than 10% liquid volume
propylene.
HD 5: A fuel of not less than 90% liquid volume
propane and not more than 5% liquid volume
propylene.
HDV: Heavy Duty Vehicle.
Heavy Ends: A term used to describe the buildup
of wax-like impurities that fall out of LPG when
vaporized.
HEGO: Heated Exhaust Gas Oxygen, used to de-
scribe a sensor. Also known as “EGO” (Exhaust
Gas Oxygen sensor), “O
2
” or “Oxygen sensor.
Hg: Chemical symbol for the element mercury.
Used in reference to a measure of vacuum (inch-
es of Hg).
Histogram:
The graphical version of a table which
shows what proportion of values fall into specific
categories over a specific period of time.
Hydrocarbon: A chemical compound made up of
hydrogen and carbon (HC). Gasoline and almost
all other fuels are hydrocarbons.
Hydrostatic Relief Valve: A pressure relief device
installed in the liquid LPG hose on a LPG fuel
system.
IAT: Intake Air Temperature
Ideal Mixture: The air/fuel ratio at which the best
compromise of engine performance to exhaust
emissions is obtained. Typically 14.7:1.
Ignition Reserve: The difference between availa-
ble voltage and the required voltage.
ILEV: Inherently Low Emission Vehicle.
IMPCO: Imperial Machine Products Company.
IMPCO Technologies, Inc. A manufacturer of both
LPG and Gasoline fuel systems.
Impedance: A form of opposition of AC electrical
current flow (resistance) measured in ohms.
Insulation: A nonconductive material used to cover
wires in electrical circuits to prevent the leakage
of electricity and to protect the wire from corro-
sion.
Intercept: An electrical term for a type of splice
where the original circuit is interrupted and redi-
rected through another circuit.
ITK: IMPCO Test Kit
Knock: Sound produced when an engine’s air/fuel
mixture is ignited by something other than the
spark plug, such as a hot spot in the combustion
chamber. Also caused by a fuel with an octane
rating that is too low and/or incorrect ignition tim-
ing. Also called detonation or ping.
Lambda Sensor: A feedback device, usually lo-
cated in the exhaust manifold, which detects the
amount of oxygen present in exhaust gases in re-
lation to the surrounding atmosphere. (See
HEGO).
LDV: Light Duty Vehicle.
Lean Mixture: An air to fuel ratio above the stoi-
chiometric ratio; too much air.
LEV: Low Emission Vehicle.
Limp-in or Limp Home: A mode where the ECM
or a component has failed, but the vehicle re-
mains operational although the engine may
operate minimally. This term may also describe
the drivability characteristics of a failed computer
system.
Liquid Petroleum Gas (LPG): A fuel commonly
known as propane consisting mostly of propane
(C
3
H
8
), derived from the liquid components of
natural gas stripped out before the gas enters the
pipeline, and the lightest hydrocarbons produced
during petroleum refining. Octane level of LPG is
107.
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