AEM 30-6905 Universal Programmable EMS-4 - Manual (Page 272)

Page 272 of 279 EMS-4 Install and Tuning Guide_Rev 1.6
Drivability
Condition describing a car in which it starts easily and idles, accelerates and shifts smoothly and
with adequate power for varying temperatures.
Driver
In automotive electronics, refers usually to a transistor circuit that is designed to either source or
sink electrical current.
Duty Cycle
In components which cycle on and off at a given frequency, the measurement of the amount of
time the component is on versus the time it is off.
Dwell
The amount of time that current is flowing through the primary side of the ignition coil. Dwell
measurements can be expressed in either units of time (usually milliseconds) or crankshaft
degrees.
ECU
Engine Control Unit. Refers to an electrical module that receives inputs from sensors and
outputs signals to actuators on an engine. Can also be referred to as EMS, PEMS, etc.
Emissions
Chemical by-products of combustion; comprised primarily of carbon monoxide (CO),
hydrocarbons (HC) and nitrous oxides (NOX).
Engine Calibration
The values contained in the controller program that are adjustable by the tuner and are used to
control engine operation, primarily fuel and spark requirements.
Engine Mapping
A procedure of experimentally determining the performance of an engine at selected operating
points and recording the results.
Equivalence Ratio
Actual air/fuel ratio divided by the air/fuel ratio at stoichiometry.
Export
To output information or data from one piece of computer software for use in another.
Gain
In closed loop control terminology, refers to constants that vary the magnitude of each term in
the manipulated variable calculation or algorithm.
Hall Effect Position Sensor