Knowledgebase: Support
Acronym List
Air filter- This device filters the air that goes into your engine. Without an air filter, harmful particles would enter your car's engine and cause internal wear and damage.
Air pump - Many emissions systems include an air pump, which pumps fresh air into a vehicle's exhaust to help complete the combustion process and reduce emissions. To get accurate lambda measurements with the LM-1, air pumps should be temporarily disabled.
ASE - After Start Enrichment, the enriched mixture provided for a number of engine cycles when an ECU detects that the engine has transitioned from cranking to running. 
Catalyst - A substance that can increase or decrease the rate of a chemical reaction between substances without being physically consumed in the process. A catalyst, which reduces engine emissions, is used in a catalytic converter. 
Catalytic converter - An in-line, exhaust system device, containing a catalyst, which reduces engine exhaust emissions. Converters are located near the exhaust manifolds or headers for maximum efficiency.
CFCO - Clutch Fuel Cut-Off
Closed loop
 - refers to those times when an EFI computer is using the feedback on the mixture provided by the oxygen sensor to effectively control the injected amounts.
Combustion - The process by which the air/fuel mixture burns within an engine to create power.
Computer (PCM) - Many modern cars have a central computer called an engine control unit (ECU) or power train control module (PCM). This controls the car's fuel and ignition systems by taking information from various sensors to determine how to run the engine with the most efficiency and power. 
Converter (Torque) - A fluid coupling device which multiplies torque between an engine and automatic transmission/transaxle. When a vehicle is stopped, a converter allows enough fluid slippage, so the engine can idle without stalling.
CTS - Coolant Temperature Sensor. Usually the CTS is an NTC (Negative Temperature Coefficient) thermistor, or a resistor whose resistance varies with temperature (NTC means the resistance goes down as the temperature goes up.
Double overhead cam (DOHC) - A DOHC engine has two camshafts in the cylinder head - one for the exhaust valves, and one for the intake valves. This allows greater efficiency and greater power.
Driver - A switched electronic device housed in a computer that controls output state. For example, a driver controls how long a fuel injector remains open.
Duty Cycle (DC)– A number indicating the amount of time that some signal is at full power. In the context of an ECU, duty cycle is used to describe the amount of time that the injectors are on, and to describe the “hold” part of the peak and hold injector drivers (see Low Impedance Injectors, below).
EGO Sensor - Exhaust Gas Oxygen sensor, used to describe the sensor in the exhaust that measures the lean/rich state of the AFR. Used to control the via a feedback algorithm called “closed loop”.
Fuel injection - Fuel injection is a system by which fuel is directly sprayed into the intake manifold or intake port at high pressure. Fuel injection is often controlled by a computer, allowing precise monitoring of efficiency and performance by the car's computer.
Fuel injector - A device for delivering metered, pressurized fuel to the intake system or individual cylinders. An injector sprays fuel, which helps atomization for a more dense mixture, when combined with incoming air.
Fuel pump - The fuel pump moves gas from the gas tank and delivers it to the fuel injection system or carburetor.
Fuel starvation - Fuel starvation occurs when fuel, for one reason or another, is prevented from reaching the carburetor or fuel injectors.
Fuel system - The fuel system is the system by which fuel is stored and delivered to each cylinder. The fuel system includes the fuel tank, fuel tank level sending unit, the fuel pump, the fuel filter, and fuel lines. For carbureted cars, the fuel system also includes the carburetor. For fuel injected cars, the fuel system also includes injectors, fuel pressure regulator and often a main computer.
G-Force - Unit of measurement used to describe lateral acceleration generated while the vehicle is driven in a steady state turn on a skid pad circle. An average sedan generates 0.60 G of lateral acceleration. Measured in "gravities", one G equals the earth's gravity at sea level.
High Impedance Injectors - (a.k.a. hi-Z) Fuel injectors designed to work with a simple switch in a 12 volt circuit, no special signal conditioning is required to drive them. The resistance of a high impedance injector is about 10-15 ohms.
IAC  Idle Air Control. Typically a “stepper motor”.
IAT sensor - Intake Air Temperature sensor, measures the inlet air temp.
Idle circuit - This is a special kind of circuit found in a carburetor that only operates when the engine is at an idle.
Ignition - Complete system used to step up battery voltage to a higher voltage and deliver it to the spark plug to complete the combustion process. When the key is turned on, the ignition system is energized.
Ignition Advance/Retard - The advancing or retarding (in crank degrees) of ignition spark relative to the piston location in the cylinder. In performance applications, the goal is to set ignition timing such that peak cylinder pressure occurs at 16-18 degrees after top dead center (TDC).
Ignition module - Part of the ignition system which instructs the ignition coil to send current to the distributor.
Ignition system - The ignition system contains the components that supply spark to the vehicle's spark plugs. These include the battery, the ignition coil, the distributor (including the cap and rotor), the spark plug wires, the ignition module, and the spark plugs themselves. Older cars also have ignition points and an ignition condenser.
Knock (Engine) - The sharp, metallic sound produced when two pressure, or flame fronts collide in the combustion chamber. This could be the result of incorrect ignition timing, incorrect air/fuel mixtures, or the wrong grade (octane rating) of gas. Also known as Detonation.
kPa (kiloPascals) - the measurement of air pressure used in some ECU computations. Average pressure at sea level is 101.3 kPa.
Lambda – the ratio between actual air/fuel ratio and stoichiometric ratio. Lambda of less than 1 is rich, and greater than 1 is lean.
Low Impedance Injectors - (a.k.a low-Z) Fuel injectors that are designed to run at a much lower current than would be supplied by a direct 12 volt connection. They require a special signal that is initially at full current (4-6 amps, a.k.a. “peak current”) for about 1.0-1.5 ms, but then drops down to about 1 amp (“hold current”) for the rest of the opening pulse. The resistance of a low-impedance injector is typically 1-3 ohms.
MAP sensor - Manifold Absolute Pressure sensor. Measure the absolute pressure in the intake manifold (related to the engine vacuum), to determine the load on the engine and the consequent fueling requirements. 
NB-EGO Sensor - Narrow Band EGO sensor, gives a switch at the stoichiometric ratio (the chemically correct mixture of air and fuel), but unreliable for AFR other than stoichiometric.
OEM (original equipment manufacturer) - refers to parts produced for initial assembly of a new vehicle. 
Open Loop - refers to those times when ECU ignores the feedback from the oxygen sensor.
P&H Injectors - Peak and hold injectors; see Low Impedance injectors.
Pulse Width Modulation (PWM) - A signal with a fixed pulse width (frequency), which is turned on for part of the pulse. The percent of time that the signal is on is called its duty cycle. PWM is used to control voltage (and consequently current) to fuel injectors.
Required Fuel – For some ECUs and EFI systems, the injector pulse width, in milliseconds, required to supply the fuel for a single injection event at stoichiometric combustion, 100% volumetric efficiency and standard temperature.
Stoichiometric Ratio- The ratio at which all available fuel is combined with oxygen during the combustion process. This theoretically ideal ratio produces minimum emissions, however maximum power is achieved at an AFR 10-15% richer than stoichiometric, while maximum efficiency is achieved at an AFR 3-5% leaner than stoichiometric (depending on many engine variables).
TPS - Throttle Position Sensor, a voltage divider that provides information about throttle opening, from which it computes rate of throttle opening for acceleration enrichment.
VE - Volumetric Efficiency. The actual amount of air being pumped by the engine as compared to its theoretical maximum. A 200 cubic inch motor will theoretically move 200 cubic inches of air in one cycle at 100% efficiency. If the engine is actually running at 75% VE, then it will move 150 cubic inches of air on each cycle.
WB-EGO Sensor - Wide Band EGO sensor, can be used to derive real AFR data with mixtures from 10:1 to 20:1, i.e. anything you are likely to be interested in.
WOT - Wide open throttle.
WUE - Warm Up Enrichment, the enriched mixture applied when the coolant temperature is low.

ABS-Anti-Lock Brake System
ADD-Adaptive Driver Demand
AutoTune-A feature that will soon be available only to people utilizing HPTuners Real Time Tuning Custom Operating systems which will allow the end user to setup some simple guidelines that will allow the scanner to self adjust your PE, VE, MAF, & Idle tables for you while you drive.
AutoVE-A feature first introduced to the LS1 market by HPTuners to simplify tuning your VE tables by simply copying and pasting the difference of your commanded air fuel ratio as compared to the actual wideband verified air fuel ratio sometimes referred to as "copy paste special".
AE-Accelleration Enrichment, the enriched mixture provided when the throttle position sensor signal changes at various rates. 
AFR - Air Fuel Ratio, the ratio of air to fuel in the combustion chamber. 
A/F - Air Fuel Ratio see above
APP Sensor = Throttle pedal on ETC vehicles
Works in the same way the ETC TPS sensors work: Voltage goes up on one sensor as you press the pedal and goes down on the other. As with the ETC the sensors must agree or the throttle goes closed.

O2 Sensors
-Bank 1 Usually refers to the drivers side ie B1S1
B2-Bank 2 Usually refers to the passenger side ie B2S1
S1-Sensor 1 Usually refers to the forward most sensor ie B2S1
S2-Sensor 2 Usually refers to the 2nd sensor in stream ie B1S2
S3-Sensor 3 Usually refers to the 3rd sensor in stream B1S3

Broadcast code
BCM-Body Control Module
BE-Boost Enrichement
Bobble Torque Management-Similar to GM's M6 spark smoothing its a "jerkiness remover" for low rpm clutch out driving
C.A.G.S.-Computer Assisted Gear Selection
CAN-Controller Area Network
CCM-Chassis Control Module
CLIP-Closed Loop Intervention Prevention
CMCV-Charge motion control valve
COS-Custom Operating System
COT-Cat Over Temp
CR-Compression Ratio
CSB-Cool Story Bro
BLM-Block Learn Memory...also usually referred to as Fuel Trims.
DMR-Direct Memory Access
DTC-Diagnostic Trouble Code
DFCO-Deceleration Fuel Cut Off
Fuel is cut off when at medium RPM and closed throttle settings. Used to lower emissions and improve fuel economy. Can also simply reduce fuel during decreasing throttle transients.

ECT-Engine Coolant Temp
EEC-Electronic Engine Control
EGR-Exhaust Gas Recirculation
Introduces exhaust gas into the intake system to reduce NOx (Oxides of Nitrogen and Nitric Oxide - NO -- Very poisonous BTW!) emissions. Achieved by cooling the combustion with inert gas (exhaust). Some systems now cool the exhaust gas before introducing it to the intake system for further NOx reduction. A side benefit (minor) is that pumping losses in the engine are reduced with a slight improvement in gas mileage. Previous statement applies *mostly* to Linear EGR valves and systems.

EGT-Exhaust Gas Temperature
EOT-Engine oil temp
ETC-Electronic Throttle Control
Drive by wire throttles. No cables. ETC encompasses a stepper motor drive to open and close the throttle and two TPS sensors. On one the voltage output increases as the throttle is opened the other decreases as the throttle is opened. If the sensors do not agree then the throttle is closed.
ESP-Electronic Stability Program
FCM-Fan Control Module
FDCM-final drive control module
FI-Fuel Injected OR Forced Induction
FTC-Fuel Trim Cell
FPCM-Fuel pump control module
FSO-Fuel Shut Off
IDC-Injector Duty Cycle
IFR-Injector Flow Rate
IMRC-Intake manifold runner control
IPW-Injector Pulse Width
In. Hg-Inches of mercury
KR-Knock Retard

KISS-Keep it simple, stupid
LID = Live In Drive (paddle pressed while in Drive)
-Long Term Fuel Trims
LTIT-Long Term Idle Trims
Long term adjustment to cover myriad operating conditions. Is a stored value in NV RAM


MAF-Mass Air Flow
MAS-Mass Airflow Sensor
MAP-Manifold Air Pressure
MCT-Manifold charge temp
MBT-Mean Best Torque
MDS-multiple displacement system(DOD)
MIL-Malfunction Indicator Light
MPH-Miles Per Hour
MPID-Memory Parameter Identification Data
MTV-manifold tuning valve
NA-Naturally Aspirated
N/V-N being engine speed, V being vehicle speed
NV RAM = Non-Volitile Random Access Memory - doesn't lose it's memory when key is turned off.
OLFA-Open Loop Fuel Adder
OEM-Original Equipment Manufacturer
OBD-On Board Diagnostics
PATS-Passive Anti-Theft System
PCM-Powertrain Control Module
PE-Power Enrichment
PRTHF-Please read the help file a nice way of saying RTFM see RTFM below
PICNIC-Problem in chair, Not in computer
PID-Parameter Identification Data
RAF-Running Air Flow
     How much air in lbs/hr or grams/Sec (g/sec) needed to keep the engine idling without stall/surge.
RTFM-Read the F&*%$#@g manual

Read or Re-read your pcm-The act of opening the editor software and clicking the Read Entire button to initiate reading the current file off of your pcm.

Reopen or open your file-The act of opening the editor software & clicking the file-open button to intitiate opening a specific file that was previously read or saved.

RPM-Revolutions Per Minute

RTT-Real Time Tuning

RWHP-Rear Wheel Horsepower
RWTQ-Rear Wheel Torque

Scan your PCM-The act of opening your VCM Scanner to log data ie Engine RPM, Vehicle speed, Spark advance, etc.

SD-Speed Density
SES-Service Engine Soon
SST = Select Shift (paddles pressed in sport and locked in)
-Short Term Fuel Trims
STIT-Short Term Idle Trims
Quick adjustment to control engine speed and prevent stall. Not stored in NV RAM

Soon-Sometime Out Of Nowhere, a fortnight, "2 weeks"

TAC = Throttle Actuator Control Module
Translates between APP Sensor and ETC to create the proper throttle opening. Interfaces with ECM to provide torque management and current throttle position. Also used on *some* cable actuated cars for torque management by relaxing the throttle cable when torque managment is requested.
TCC - Torque Converter Clutch
TCM-Transmission Control Module
TQMT-Torque Management
TM-Torque Management
Used to control wheel spin or slip (think icy roads or TT vehicles) in conjunction with the anti lock brake system (ABS). Reduces engine power by reducing torque output of the engine usually by reducing spark advance considerably or closing the throttle on ETC vehicles. Also used to prolong transmission life (at least through warranty...) by reducing engine output (reducing spark advance) during shifts.

TT = Twin Turbo (usually)
VATS-Vehicle anti-theft system
VE-Volumetric efficiency
VID-Vehicle Identification
VCM-Vehicle Control Module
VCT-Variable Cam timing
VSS-Vehicle Speed Sensor

AIR : Secondary Air Injection
APP: Accelerator Pedal Position
BARO: Barometric Pressure
BPP: Brake Pedal Position
BPS: Brake Pedal Switch
BTDC: Before Top Dead Center. The location of the piston before it has reached the top of its stroke. Measured in degrees of crankshaft rotation.
CAN: Controller Area Network
CCM: Comprehensive Component Monitor
CHT: Cylinder Head Temperature
CKP: Crankshaft Position
CMCV: Charge Motion Control Valve
CMP: Camshaft Position
COP: Coil On Plug. Ignition coil on plug assembly
CPP: Clutch Pedal Position
ECM: Electronic Control Module
ECT: Engine Coolant Temperature
EEC: Electronic Engine Control
EEGR: Electric Exhaust Gas Recirculation System
EEPROM: Electrically Erasable Programmable Read-Only Memory. An electronic component in the PCM that allows the electronic storage of information.
EGR: Exhaust Gas Recirculation. A process in which a small amount of exhaust gas is routed into the combustion chamber.
EI: Electronic Ignition. An electronic ignition system that has the ignition control module integrated into the PCM.
EMI: Electromagnetic Interference. Usually caused by ignition voltage spikes, solenoids, relay operation, or noisy generator contacts.
EOT: Engine Oil Temperature
ERFS: Electronic Returnless Fuel System
ESM: EGR System Module
ESOF: Electronic Shift-on-the-Fly
ETB: Electronic Throttle Body"

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