AEM 30-6905 Universal Programmable EMS-4 - Manual (Page 270)

Page 270 of 279 EMS-4 Install and Tuning Guide_Rev 1.6
BDC
Bottom dead center; the extreme lowest position of the piston during its stroke.
Boost
Describes positive pressure in the intake manifold relative to atmospheric pressure. Standard
atmospheric pressure is 14.5 psia. 10 psi of boost would result in 24.5 psia in the manifold.
Breakpoints
Define the axis values on two dimensional or three dimensional lookup tables
BSFC
Brake Specific Fuel Consumption or BSFC is the fuel flow rate per unit power output. It
measures how efficiently an engine is using the fuel supplied to produce work.
Calibration
Engine calibration in its most basic form is the setting of the air/fuel ratio and ignition timing for
the engine. Modern electronic engine control systems serve many more functions though.
These can include: idle control, automatic transmission control, turbocharger boost control and
knock control. The engine controller can also be used to enable/disable ancillary functions like
emissions control solenoid valves (EVAP/purge, air injection), air conditioner compressor clutch
relays, etc. The engine calibrator is responsible for configuring and tuning all of these items to
satisfy the performance requirements for the engine.
Capacitor
An electronic device that stores electrical charge.
Closed Loop Fuel Control
An engine control mode of operation where the air/fuel ratio is controlled by varying the fuel flow
rate in response to the rich/lean indication from an exhaust
Coil
For ignition system is comprised of two sets of insulated wire wound around a common ferrous
core. The primary winding is typically made up of tens or hundreds of turns of course wire. The
secondary winding is made up thousands of turns of fine wire. A single set of coil windings can
be used to build a solenoid that converts electrical field energy into mechanical movement.
Coil on Plug
Refers to ignition systems that include one coil for each spark plug. Most modern automotive
ignition systems are of this type.
Cold Start
Starting the engine when it is cold; when the engine has not run for several hours.