List of acronyms relevant to EFI.
An 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 computer.
  • 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 element.
  • 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 Unit)
  • MIL* = Malfunction Indicator Lamp. "Check engine" light.
  • MFI* = Multiport Fuel Injection.  One (or more) injectors per cylinder.
  • 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 tools
  • OEM = Original Equipment Manufacturer
  • OT = Injector On-Time (or Open Time)
  • PCM* = Powertrain Control Module. ECM with transmission control capability.
  • 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 events.(=SEFI =SPFI)
  • 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 carb.
  • 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, and hydrcarbons.
  • UEGO = Universal Exhaust Gas Oxygen. Wide-range air-fuel ratio sensor.
  • ULEV = Ultra Low Emission Vehicle
  • VE = Volumetric Efficiency.  Actual air mass ingested in a cylinder divided by maximum possible (i.e. at atmospheric pressure).
  • VSS* = Vehicle Speed Sensor
  • VTEC = Variable valve Timing and lift Electronic Control
  • WOT* = Wide Open Throttl