of acronyms relevant to EFI.
asterisk (*) indicates terminology standardized in SA
- ACT = Air Charge Temperature. (= IAT*)
- ADC = Analog to Digital Converter
- A/D = Analog to Digital
- AE = Acceleration Enrichment
- A/F = Air Fuel Ratio (also AFR)
- ALDL = Assembly Line Diagnostic Link. The connector under
the dash on non-OBDII GM cars. It can be used to dump
diagnostic information from the ECM with special equipment.
- BLM = Block Learn Multiplier (or Matrix or Memory). A
parameter in the fuel control strategy that is adapted using
O2 sensor feedback (= long term FT*).
- BP = Barometric Pressure
- BPC = Base (fuel) Pulse Constant
- BDC = Bottom Dead Center
- C3I = Computer Controlled Coil Ignition (=EI*)
- CAC* = Charge Air Cooler, i.e. intercooler
- CAN = Controller Area Network. A network protocol
used on overseas vehicles. The US standard protocol
is specified in SAE J1850, aka OBD.
- CARB* = Carburetor. (Also California Air Resources Board)
- CDI = Capacitive Discharge Ignition
- CFI* = Continuous Fuel Injection (also, Central Fuel Injection)
- CKP* = Crankshaft Position (sensor)
- CIS = Continuous Injection System (= CFI*)
- CL* = Closed Loop
- CMP* = Camshaft Positon (sensor)
- CPU = Central Processing Unit
- CTS = Coolant Temp Sensor (= ECT* sensor)
- CYA = Cover Your Ass
- DAC = Digital to Analog Converter
- DFCO = Deceleration Fuel Cut-Off
- DE = Deceleration Enleanment
- DI* = Distributor Ignition
- DIS = Distributorless Ignition System
- DLC* = Data Link Connector
- DLI = Distributor-Less Ignition (=EI*)
- DSP = Digital Signal Processor
- DTC* = Diagnostic Trouble Code. Self-test codes.
- ECM* = Engine Control Module. It's the engine management
- ECT* = Engine Coolant Temperature
- ECU = Electronic Control Unit (= ECM*)
- EEC = Electronic Engine Control (Ford's ECM)
- EFI = Electronic Fuel Injection
- EGO = Exhaust Gas Oxygen (= O2S*)
- EGR* = Exhaust Gas Recirculation
- EGT = Exhaust Gas Temperature
- EI* = Electronic Ignition
- EOI = End of Injection
- EPROM* = Erasable Programmable Read-Only Memory
- EEPROM* = Electrically Erasable PROM
- EST = Electronic Spark Timing
- F/A = Fuel-Air Ratio
- FEEPROM* = Flash EEPROM
- FMEM = Failure Mode Effects Management. Alternative vehicle
operation strategy in the event of a system failure.
- FT* = Fuel Trim. Generally seen with the words "long
term" or "short term".
- HEGO = Heated EGO (sensor). (= HO2S*)
- HO2S* = Heated Oxygen Sensor. Sensor has built-in heating
- HEI = High Energy Ignition
- IAC* = Idle Air Control. A motor controlled by the
ECM. It determines how much air gets through to the
engine at idle. The computer controls it to maintain
a constant idle speed.
- IAT* = Intake Air Temperature
- IGBT = Insulated Gate Bipolar Transistor
- INT = Integrator (= short term FT*)
- ISC = Idle Speed Control (= IAC*)
- KAM = Keep Alive Memory. Parameters stored in the ECM,
can be lost if power is removed.
- KS* = Knock Sensor
- MAF* = Mass Air Flow. The mass of air flowing into
the intake is directly measured via a hot wire, rotating
vane, or hinged flap. The computer reads this value
and injects the proper amount of fuel.
- MAP* = Manifold Absolute Pressure. The air pressure
in the intake.
- MAT = Manifold Air Temperature (= IAT*)
- MCU = Microprocessor Control Unit (or Microcontroller
- MIL* = Malfunction Indicator Lamp. "Check engine" light.
- MFI* = Multiport Fuel Injection. One (or more) injectors
- MPI = MultiPoint or MultiPort Fuel Injection (= MFI*)
- O2S* = Oxygen Sensor
- OBD* = On-Board Diagnostic. A system to monitor
operation of the emissions control system. SAE J1850 standardizes
the communication protocols and connectors for diagnostic
- OEM = Original Equipment Manufacturer
- OT = Injector On-Time (or Open Time)
- PCM* = Powertrain Control Module. ECM with transmission
- PE = Power Enrichment
- PFI = Port Fuel Injection (= MFI*)
- PIP = Profile Ignition Pickup (= CMP*)
- PLCC = Plastic Leadless Chip Carrier
- PWM = Pulse Width Modulated
- SAE = Society of Automotive Engineers
- SBC = Single Board Computer or Small Block Chevy
- SD = Speed-Density. The amount of air entering the
engine is calculated from engine RPM, MAP, IAT, and an ECM-stored
volumetric efficiency table for the engine.
- SFI* = Sequential multiport Fuel Injection. Fuel injection
is timed with respect to individual cylinder intake valve
- SNAFU = Situation Normal - All F*ck'd Up
- SOI = Start of Injection
- SOL = Shit Out of Luck
- SPI = Single Point Injection (=TBI*)
- TBI* = Throttle Body Injection. One or more injectors
located at the throttle body, basically a more efficient
- TCC* = Torque Converter Clutch
- TDC = Top Dead Center. Piston is at the top of the cylinder.
- TPI = Tuned Port Intake. Resonance characteristics used
to increase airflow.
- TPS* = Throttle Position Sensor. Tells the ECM how
"open" the throttle is.
- TWC* = Three Way Catalyst. Takes care of NOx, CO,
- UEGO = Universal Exhaust Gas Oxygen. Wide-range air-fuel
- ULEV = Ultra Low Emission Vehicle
- VE = Volumetric Efficiency. Actual air mass ingested
in a cylinder divided by maximum possible (i.e. at atmospheric
- VSS* = Vehicle Speed Sensor
- VTEC = Variable valve Timing and lift Electronic Control
- WOT* = Wide Open Throttl