# Acronyms, Abbreviations and Terminology ## This document contains all of the commonly used acronyms, abbreviations and terminology used by rusEFI
AAP Absolute Atmosphere Pressure
AFR Air Fuel Ratio - See also Lambda, Stoichiometric AFR is the ratio of air to fuel, often expressed as "14.7:1"
AIT Air Intake Temperature
AWG https://en.wikipedia.org/wiki/American_wire_gauge
Baro Shorthand for Barometric pressure
BTDC Before TDC, Before Top Dead Center - See also ATDC
BMEP Brake mean effective pressure
CAS Crank Angle Sensor Also See [CPS - Wikipedia]]()
CLT Coolant Temperature, same as ECT
CoV Coefficient of variability
CPS Crankshaft Position Sensor
CR compression ratio
DI Direct injection
DISA BMW variable inlet manifold resonance system
EDIS Electronic Distributorless Ignition System - An older Ford ignition system that combined a set of ignition IGBTs and some electronics to assist the ECU. Obsolete on modern ECUs.
EGO Exhaust Gases Oxygen - see also lambda sensor, WBO2, Often used when referring to air fuel sensors like the lambda sensor. Sometimes also used as HEGO or Heated Exhaust Gas Oxygen.
EGR Exhaust gas recirculation
EGT Exhaust gas temperature
EOI End Of Injection - See also SOI
ETB Electronic throttle body
EVC Exhaust valve closing
EVO Exhaust valve opening
GDI Gasoline Direct Injection
Hall A type of sensor that requires a power and earth wire in addition to its signal wire, the output is normally a 5v square wave.
High Side A driver that is open circuit when off and powered to 5v or 12v when on.
High/Low a pushpull or HighLow is an output that is powered "high" (12v or 5v) and switched to low (earth).
High and Low Z High and low resistance, used in terms of fuel injectors, normally around 14 ohms for high impedance and ~4 ohms for low.
IAT Intake Air Temperature
IFR Injector Flow Rate
IGBT [IGBT - Wikipedia]]() A common type of transistor used for switching high power devices like ignition coils with a low power/voltage output.
IMEP Indicated mean effective pressure
Injector Impedance The resistance of the fuel injectors, see high and low Z
IPW Injector Pulse Width
IVC Intake valve closing
IVO Intake valve opening
Low side A driver that is open circuit when off and grounded to earth when switched on.
LQFP Low profile quad flat package
MAF Mass Air Flow, often used in the context of air flow or load sensors.
MAP Manifold Absolute Pressure or perhaps Manifold Air Pressure, often used in the context of load sensors.
MBT Mean best timing, used in context of spark timing, it is the spark timing that results in the best torque
MLV Mean the tool MegaLogViewer
MFB Mass fraction burned, often stated with a number after i.e. MFB10/MFB50/MFB90 and refers to the fraction of the fuel burned by mass.
MRE Micro rusEFI
NGC Chrysler Next Generation Controller
NTC Negative temperature coefficient, used in context of temperature sensors and refers to the resistance increasing as temperature decreases.
PIP Profile ignition pickup See [Profile Ignition Pickup - Wikipedia]]()
PFI Port fuel injection
PID A proportional–integral–derivative controller
PNP Plug and play
PPS Pedal Position Sensor
Primary Coil The primary winding of an ignition coil
RE rusEFI
REO rusEFI Online
RUSEFI Really Uber Simple EFI? Robust Ultra Simple EFI? Retarded Unproven Shitty EFI?
Secondary Coil The secondary winding of an ignition coil.
Sequential Often this refers to Sequential injection, which means the injectors fire individually for each cylinder and often at a specific crank angle. This can be handy for engines direct injection or to try to spray the injector into the cyl while the intake valve is open. If an engine can inject onto an open inlet valve it will reduce the amount of fuel wetting the port walls and help reduce low load emissions. Sequential is required for direct injection engines like common rail diesel.
SBC Small Block Chevy
SD Speed Density this is a method of predicting how much fuel should be delivered to an engine. This is a MAP based system which uses pressure to make a prediction of how much O2 is entering the cyl.
SI Spark injection
Smart Coil A type of ignition coil that has its ignition drivers (IGBT) built into the coil, this means they only receive a 5v signal to activate.
SMD Surface mount device, interchangeable with SMT
SMT Surface mount technology, interchangeable with SMD
SOI Start Of Injection - See also EOI
Staged injection The use of 2 injectors for one cyl. This commonly means at low RPM and lower loads, one injector is turned on which allows for finer control over idle fuel delivery, while at higher RPM and higher Loads both injector inject fuel which allows for larger amounts of fuel to be delivered.
Stoichiometric The ideal quantity of fuel to burn with a quantity of air for complete combustion. For gasoline this is 14.7:1, ethanol is 9:1 and methanol 6.47:1
SOIC small outline integrated circuit
TDC Top Dead Center
TPS Throttle Position Sensor
TMAP A sensor combining IAT ("Temperature") and MAP
TE TE connectors, they produce the ampseal connectors on the proteus and a lot of OEM ECUs.
TFI Thick Film Ignition - Ford distributor - Likely unsupported at this time.
TFSI Turbo Fuel Stratified Injection - A VW direct injection lean burn strategy
TLE Short for TLE8888 the Infineon chip on the MRE
TVIS Toyota variable intake system, a variable inlet length system that switches on/off a set of longer intake manifold runners.
Valvetronic BMW variable valve lift system
VANOS BMW variable valve timing system
VCC Common Collector Voltage; the positive supply voltage for an integrated circuit
VDD the DC Power supply connected to Drain Terminal of any FET circuit.
VE Volumetric Efficiency, often expressed as a decimal value i.e. 0.8 (for 80%)
VISA BMW variable inlet manifold length system
VOL Short for engine volume
VSS Vehicle speed sensor
VVT Variable valve timing
WBO Wide Band Oxygen, same as EGO
WOT Wide Open Throttle