Common EFI Abbreviations

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Common EFI Abbreviations

Postby antus » Sun Aug 09, 2009 3:29 pm

This data was originally sourced from and has been updated.

ADC: Analog to Digital Converter
A/D: Analog to Digital
AFR : Air Fuel Ratio (sometimes written as A/F) - ideal ratio of 14.7:1 (for unleaded petrol) gives low emissions and acceptable drivability and economy. A lower ratio (11:1) would be "rich" and a higher ratio (16:1) "lean".
ALDL : Assembly Line Diagnostic Link
BDC : Bottom Dead Center
BLM : Block Learn Multiplier - the factor which is "learned" to adjust fuel mixture as the tolerances on the factory system change over time.
BP : Barometric Pressure
BPW : Base Pulse Width - the calculated length of the pulse, or "on-time" of the fuel injector before any "tweaking" for minor inputs such as air temperature.
CAN : Controller Area Network. A proposed network protocol for automotive use outside the US. The US proposal is SAE standard J1859, aka OBD.
CAS: Crank angle sensor
CDI : Capacitive Discharge Ignition.
CEL : Check Engine Light - a dashboard light (same as SES) letting you know the car has a problem and also used to flash out diagnostic codes stored by the ECM.
CFI : Crossfire Fuel Injection - an intake manifold utilizing 2 diagonally mounted throttle bodies (model 300s?), hence it's another TBI injection system. The twin 300s together are called the model 400.
CFI : Central Fuel Injection - a FoMoCo designation. Similar to GM's TBI injection system.
CFI : Continuous mechanical Fuel Injection - yet another injection system. This one used on Volvos.
Crossings : the number of times the O2 sensor switches across stoich. It is a measure of closed loop system performance.
CTS : Coolant Temp Sensor
DAC : Digital to Analog Converter
DIS: Distributorless Ignition System
EEC : Evaporative Emission Control system - a method of purging fuel vapors (don't tell the Ford faithful whose EFI controller is known as the EEC-IV or EEC-V)
ECCS: Older nissan fuel injection system
ECM : Electronic Control Module (sometimes also ECU Electronic Control Unit, or PCM Powertrain Control Model when controlling the transmission too) - the engine management computer.
EGO : Exhaust Gas Oxygen sensor
EGR : Exhaust Gas Recirculation - use to reduce emissions and increase economy supposedly
EGT : Exhaust Gas Temperature
EPROM : Electrically Programmable Read-Only Memory - this is the replaceable memory chip which contains fuel and spark information and allows one ECM to be used in various applications.
ESC : Electronic Spark Control - aka Retard Signal. Used to retard the timing when detonation (knock) is detected.
EST : Electronic Spark Timing
FUBAR : F***ed Up Beyond All Recognition
HEI : High Energy Ignition
IAC : Idle Air Control - (a controlled vacuum leak) A stepper motor controlled by the ECM. It determines how much air gets through to the engine when the throttle is at idle. The ECM controls it to maintain a programmed idle speed.
IAT : Intake Air Temperature. Similar (equivalent?) to MAT Manifold Air Temperature.
ION : A patented (by Saab) method for detecting "knock" or misfire in an engine by measuring a current across the sparkplug electrode known as an ionization current.
ISCV : Idle Speed Control Valve
MAF : Mass Air Flow (sensor) - an alternative to MAP. This measures actual airflow into the engine and thus doesn't need to make any calculations based on VE.
MAP : Manifold Air Pressure (sensor) - a vacuum gauge. BPW fueling is primarily computed from this input on cars so equipped. Another alternative would be MAF.
MAT : Manifold Air Temperature sensor
MCU : MicroController Unit (eg. 68HC11) - the processor on which the engine computer is based
MPFI: Multi-Port Fuel Injection (see MPI)
MPI : Multi-Port Injection - generic name for any of the port injection systems (as opposed to TBI systems)
O2 (see also EGO) : Typical slang referring to the Oxygen sensor
OBD: On Board Diagnostics. Mandated in the US, this forces auto manufacturers to use a set of a defined number of hardware and similar software protocols on different pins of a standard OBD Port for automotive diagnostics.
OEM : Original Equipment Manufacturer
PLCC : Plastic Leadless Chip Carrier
PPM : Pulse Per Mile - in reference to VSS
PWM : Pulse Width Modulator
RPM : Revolutions Per Minute - typically sensed by a sensor in the distributor or on the crankshaft.
SAE : Society of Automotive Engineers
SBC : Single Board Computer or Small Block Chevy
Scantool : A piece of test equipment which plugs into the ALDL and displays Trouble Codes and other information helpful for servicing of the ECM.
SD : Speed density. An FI technique where the amount of air entering the engine is calculated from engine RPM, MAP, and a pre-calculated volumetric efficiency for the engine.
SES : Service Engine Soon light - aka "CEL Check Engine Light"
SFI : Sequential Fuel Injection - injectors are fired in ignition firing order for maximum performance and economy.
TB: Throttle Body
TBI : Throttle Body Injection - basically a fully electronic computer controlled carburetor
TCC : Torque Converter Clutch - a lockup mechanism for improved economy and performance
TDC : Top Dead Center. Piston at the top of the cylinder.
TPI : Tuned Port Injection - intake manifold and EFI system used on Camaros and Corvettes especially
TPS : Throttle Position Sensor. Tells the ECM how "open" the throttle is.
VE : Volumetric Efficiency - the ratio of the amount of air going into an engine to the volume displaced by the movement of the pistons. EG How efficiently it can fill the cylinder volume with air, usually by RPM and pressure.
VIN : Vehicle Identification Number - needed when using the scantool
VSS : Vehicle Speed Sensor
Have you read the FAQ? For lots of information and links to significant threads see here: viewtopic.php?f=7&t=1396

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Re: Common EFI Abbreviations

Postby yoda69 » Thu Sep 24, 2009 10:02 am

This list was sourced from

A/F Air fuel Ratio
A/C Air conditioning
ABDC After Bottom Dead Center
ABS Anti-Lock Braking System
AC Alternating Current
AE Acceleration Enrichment
AFR Air Fuel Ratio
AIR Air Injection Reaction
AIT Air Intake Temp
ALCL Assembly line communications link
ALDL Assembly Line Diagnostic Link
Async Fuel delivery Asynchronous to engine timing
AT Automatic Transmission
ATDC After Top Dead Center
AWG American Wire Gauge
Baro Barometric Pressure
BBDC Before Bottom Dead Center
BCM Body Control Module
BLM Block Learn Multiplier
bpw base pulse width
BTU British Thermal Units
C Celsius
C/L Closed Loop
C3 GM ECM using Motorola 68xx-like processor (1+ MHz CPU)
CCP Controlled Canister Purge
CEL Check engine light (see MIL, SES)
CID Cubic Inch Displacement
CKP crankshaft position sensor
CMP camshaft position sensor
CP Canister Purge
CPU Central Processor Unit (the brains in the ecm)
CTS Coolant Temp Sensor
DB Decibels
DC Duty Cycle On time, compared to total event time expressed as a
DC Direct Current
DE Decel Enleanment
DFCO Decleration Fuel Cut Off
DIS Distributorless Ignition System
DVM Digital Multi Meter
ECM Engine Control Module
ECT engine coolant temp
ECU Engine Control Unit
EFI Electronic Fuel Injection
EGR Exhaust Gas Recirculation
EGT Exhaust Gas Temp
EPROM Erasable Programable Read Only Memory
ESC Electronic Spark Control (Knock Control)
EST Electronic Spark Timing
F Fahrenheit
FED Federal (emissions package)
GPS Grams per sec
hego heated exhaust gas oxygen
HEI High Energy Ignition
HO2S heated o2 sensor
I/O Input/Output
IAC Idle Air Control
IAT Intake Air Temp
IC Integrated Circuit
ICE Internal Combustion engine
IGN Ignition
Injector On Time Time in milliseconds that an injector is on.
INT Integrator
IPW Injector Pulse Width
IS Idle Speed
ISC Idle Speed Control
kapwr keep alive power
kg Kilogram
Kilohertz (1,000s cycles / sec)
kPa Kilopascals (Pressure)
KS Knock Sensor
L Liter (about 60 cubic inches)
LCD Liquid Crystal Display
MAF Mass Air Flow
MAP Manifold Absolute Pressure
MAT Manifold Air Temp
MDP Manifold differential Pressure
MEMCAL Memory Calibration Unit
MFI Multi-port Injection
MIL malfunction indicator lamp (see CEL, SES)
MT Manual Transmission
NC Normally Closed
NEU Neutral
NO Normally Open
NPTC National Pipe thread Course
NTPF National Pipe Thread Fine
O2 Sensor for detecting rich lean exhaust mixtures, GM so far uses this
type, and it has a high slew rate and therefore is more of a switch
OBD2 on board diagnostics, newer vehicle electronics, less friendly
OL Open Loop
OTS Oil Temp Sensor
P/N park neutral switch
P+H one way of firing an injector High initial voltage to open then
lower to keep it open
P4 GM ECM using early Motorola 68HCxx-like processor (2+ MHz CPU)
PCM Powertrain Control Module (engine and trans control)
PE Power Enrichment
Port, MPFI, Multi Port, each cyl has it's own injector close to the
intake valve
PS Power steering
PSI Pounds per square inch
PSIA PSI absolute
PW Pulse Width
PWM Pulse Width Modulation
QT Quart
R-12 Refrigerant
RAM Random Access Memory
RAP Retained Accessory Power
RFI Radio Frequency Interference
ROM Read Only Memory
RR Right Rear
RTV Room Temperature Vulcanizing
RWD Rear wheel drive
SEFI Sequential Electronic Fuel Injection
SES Service Engine Soon (see MIL, CEL)
SI Saturated Injector *constant* voltage current
SynchPulse Fuel PW with delivery tied to timing of ref pulses
TAC Thermostatic Air Cleaner
TB Throttle Body
TBI Injection system where the injectors are mounted above the
TCC Torque Converter Clutch
TCM Transmission Control Module
TDC Top Dead Center
TFT trans fluid temp
TH Turbo-Hydramatic
TPI Tuned Port Injection
TPS Throttle Position Sensor
TRC Throttle Return Control
TTS Trans Temp Sensor
TV Throttle Valve
TVS Thermal Vacuum Switch
VATS Vehicle Anti Theft System
VE Volumetric Efficiency
VSS Vehicle Speed Sensor
WBO2 this sensor differs from the O2 in so far that it is designed for
a *linear* output
WG WasteGate
WOT Wide Open Throttle

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Re: Common EFI Abbreviations

Postby Agroeureka » Thu Sep 24, 2009 5:26 pm

I had been trying to work out som of these


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Re: Common EFI Abbreviations

Postby antus » Sun May 08, 2011 8:24 pm

XDF: Tunerpro 5 definition - Tells tuner pro what is where in the bin, and how to interpret it.
ADX: Tunerpro 5 data stream definition - Tells tuner pro how to get logging information from the ecu, what data is in the stream, how to interpret it, and provides the dashboard screen layout.
DEF: A definition (eg XDF, ADX for tunerpro, and also might refer to other types of file for other tuning packages.
BIN: "Binary". Usually refers to the binary image of all the data on a memcal. Both the program (operating system) and the vehicle specific calibration.
Have you read the FAQ? For lots of information and links to significant threads see here: viewtopic.php?f=7&t=1396

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Re: Common EFI Abbreviations

Postby immortality » Sun Oct 26, 2014 6:55 pm

Hi guys,

Having a total brain fart.... What does NTRPM (as in Fuel Air Timeout - Reduction Freq. V's NTRPM - P/N/D ) mean please?

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Re: Common EFI Abbreviations

Postby The1 » Sun Oct 26, 2014 7:16 pm


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