318
Air Valve Vacuum (AVV): The vacuum signal tak-
en from below the air valve assembly and above
the throttle butterfly valve.
ADP: Adaptive Digital Processor.
Air/Fuel Ratio: The amount or balance of air and
fuel in the air fuel mixture that enters the engine.
Analog Voltmeter: A meter that uses a mechani-
cal needle to point to a value on a scale of
numbers. It is usually of the low impedance type
and used to measure voltage and resistance.
Aromatics: Pertaining to or containing the six-
carbon ring characteristic of the benzene series.
Found in many petroleum distillates.
Backfire: Combustion of the air/fuel mixture in the
intake or exhaust manifolds. A backfire can occur
if the intake or exhaust valves are open when
there is a mis-timed ignition spark.
Benzene: An aromatic (C
6
H
6
). Sometimes blended
with gasoline to improve anti-knock value. Ben-
zene is toxic and suspected of causing cancer.
Bi-Fueled: A vehicle equipped to run on two fuels.
Blow-By: Gases formed by the combustion of fuel
and air, which ordinarily should exert pressure
only against the piston crown and first compres-
sion ring. When rings do not seal, these gases
escape or “blow by” the side of the piston into the
crankcase.
BTU: British Thermal Unit. A measurement of the
amount of heat required to raise the temperature
of 1lb. of water 1 degree F.
Butane: An odorless, colorless gas, C
4
H
10
found in
natural gas and petroleum. One of the five LP
gases.
CAFE: Corporate Average Fuel Economy.
CARB: California Air Resources Board.
Carbon Monoxide (CO): A chemical compound of
a highly toxic gas that is both odorless and color-
less.
Carburetor: An apparatus for supplying an inter-
nal-combustion engine a mixture of vaporized fuel
and air.
Cathode Ray Tube: A vacuum tube in which ca-
thode rays usually in the form of a slender beam
are projected on a fluorescent screen and pro-
duce a luminous spot.
Circuit: A path of conductors through which elec-
tricity flows.
Closed Loop Operation: Applies to systems utiliz-
ing an oxygen sensor. In this mode of operation,
the system uses oxygen sensor information to de-
termine air/fuel ratio. Adjustments are made
accordingly and checked by comparing the new
oxygen sensor to previous signals. No stored in-
formation is used.
CNG: Compressed Natural Gas.
CKP: Crankshaft Position Sensor
CMP: Camshaft Position Sensor
Conductor: A material, normally metallic, that
permits easy passage of electricity.
Contaminants: Impurities or foreign material
present in fuel.
Control Module: One of several informal names
for a solid state microcomputer which monitors
engine conditions and controls certain engine
functions; i.e. air/fuel ratio, injection and ignition
time, etc. The formal name and the one used
throughout this manual is ECM, or Engine Control
Module.
Converter: A LPG fuel system component contain-
ing varying stages of fuel pressure regulation
combined with a vaporizer.
Cryogen: A refrigerant used to obtain very low
temperatures.
Current: The volume or flow of electrons through a
conductor. Measured in amperes or amps.
DBW: Drive By Wire
Dedicated Fuel System: A motor fuel system de-
signed to operate on only one fuel type.
Diaphragm: A thin, flexible membrane that sepa-
rates two chambers. When the pressure in one
chamber is lower than in the other chamber, the
diaphragm will move toward the side with the low
pressure.
Diaphragm Port: The external port located at the
fuel inlet assembly and connected to the vacuum
chamber above the air valve diaphragm.
DLC: Data Link Connector.
DTC: Diagnostic Trouble Code
DST: Diagnostic Scan Tool.
DVOM: Digital Volt/ohm Meter. A meter that uses a
numerical display in place of a gauge and is
usually of the high impedance type.
ECT: Engine Coolant Temperature.
ECM: Electronic Control Module
ECOM: A DLC cable supporting CAN and serial
communication with a Spectrum II or III ECM.
EFI: Electronic Fuel Injection. A fuel injection sys-
tem, which uses a microcomputer (ECM) to
determine and control the amount of fuel, re-
quired by, and injected into, a particular engine.
EGO: Exhaust Gas Oxygen, used to describe a
sensor. Also known as “HEGO” (Heat Exhaust
Gas Oxygen) sensor, “O
2
” or “Oxygen sensor.
EGR: Exhaust Gas Recirculation.
EPA: Environmental Protection Agency: A regulat-
ing agency of the Federal government which,
among other duties, establishes and enforces au-
tomotive emissions standards.
To Next Page
Loading...