Common EFI Abbreviations
Posted: Sun Aug 09, 2009 3:29 pm
This data was originally sourced from http://www.aces.edu/~parmega/efi/glossary.htm 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
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