AEM 30-6905 Universal Programmable EMS-4 - Manual (Page 276)

Page 276 of 279 EMS-4 Install and Tuning Guide_Rev 1.6
the air. For gasoline, this ratio is 14.7:1 or 14.7 parts of air to 1 part fuel.
Switch
A device that can break an electrical connection interrupting the current or diverting it from one
conductor to another.
Switched Ground
Using an electromechanical of electronic switch to connect a circuit element to a ground
reference.
Switched Power
Battery power provided to the system when the ignition switch is in both the "run" and "start"
positions.
Tile
Software feature allowing multiple windows to be displayed at once.
Torque
Torque is a measure of an engine's ability to do work. Engine torque is normally measured with
an engine dynamometer.
Trims
Alternate term used to describe correction tables in an engine calibration file.
TXD
Abbreviation for Transmit Data
uS
Abbreviation for microsecond or one ten thousandth of a second or 0.0001 seconds.
USB
Universal Serial Bus (USB) is a serial bus standard to connect devices to a computer. Other
convenient features include providing power to low-consumption devices, eliminating the need
for an external power supply; and allowing many devices to be used without requiring
manufacturer-specific device drivers to be installed.
Vacuum
Vacuum is measured in units of pressure. In automotive technology, vacuum is often measured
using inches of mercury on the barometric scale or as a percentage of atmospheric pressure in
bars or atmospheres. Low vacuum is often measured in inches of mercury (inHg) below
atmospheric pressure. "Below atmospheric" means that the absolute pressure is equal to the
current atmospheric pressure (e.g. 29.92 inHg) minus the vacuum pressure in the same units.
Thus a vacuum of 26 inHg is equivalent to an absolute pressure of 4 inHg (29.92 inHg - 26
inHg). The reciprocating motion of the pistons in an internal combustion engine create a vacuum