Glossary Of EFI Terms

AFC (Air Flow Control) − Any fuel injection system which uses a meter or sensor to measure intake air for the primary control of amount of fuel to be injected.
CIS (Continuous Injection System) − Refers to any fuel injection system which continuously injects fuel through some type of injector responsive to pressure only. This is basically a mechanical system in which later designs are refined with electronic controls.
CIS-E − An electronically controlled version of CIS. Typically Bosch KE-Jetronic.
CFI (Central Fuel Injection) − Ford Throttle Body Injection (TBI) system using a single-port unit, mounted in place of the carburetor and using one or two injectors to supply fuel into the intake manifold.
CPFI (Central-Port Fuel Injection) − This is a hybrid mechanical and electronically-pulsed fuel injection system. Used on Chevrolet and GMC trucks, the system pulses an injector which meters fuel through a flexible line to a mechanical poppet valve located at each cylinder.
DFI (Digital Fuel Injection) − One of the Throttle Body Injection (TBI) systems used on Cadillac.
D-JETRONIC − A Bosch fuel injection system that uses intake manifold pressure to control the amount of fuel injected.
ECM/ECU (Electronic Control Module/Unit) − The on-board control unit for the fuel injection system which receives all the input signals, processes them, and sends out control signals to the injectors and other control devices.
EFI (Electronic Fuel Injection) − Refers to any system which uses some form of an electronic injector, opened only by a signal from the ECM/ECU. Also refers to the GM multi-port fuel injection system used on 1975-80 Cadillac.
FI (Fuel Injection) − Used to mean that an engine is equipped with some type of fuel injection system.
K-JETRONIC − A Bosch Continuous Injection System (CIS) that relies on pressure to open injectors and a fuel distributor which varies the quantity of fuel.
KE-JETRONIC − An updated Bosch K-Jetronic system that includes an oxygen sensor and a pressure control valve for feedback system to control the air/fuel ratio.
LAMBDA − Term used to describe the “ideal” air/fuel ratio, usually 14.7:1.
LAMBDA SENSOR − Usually called the oxygen (O2) sensor, this sensor is used to measure oxygen content of the exhaust gas to indicate a lean or rich mixture compared to the perfect balance.
  L-JETRONIC − A Bosch Multi-Port Fuel Injection (MPFI) system that uses an air flow meter to adjust fuel injection to meet demand.
LE/LU-JETRONIC − An updated Bosch L-Jetronic Multi-Port Fuel Injection (MPFI) system either equipped with an electronic feedback system (LE) or limited to unleaded fuel use only (LU).
MAF (Mass Air Flow) − The volume, temperature, and density of the incoming air. A MAF sensor provides information to the controller for regulation of fuel supply.
MAP (Manifold Absolute Pressure) − The negative (less than atmospheric) pressure in the intake manifold of a running engine. A MAP sensor can detect this pressure, and send a signal to the controller to indicate engine load and fuel requirements. This may be a combination unit which also measures atmospheric pressure, and is then called a B/MAP sensor.
MFI/MPFI (Multi-Port Fuel Injection) − Describes a system that uses one injector for each cylinder of the engine. The injectors are normally opened in groups, rather than individually.
MONO-TRONIC − A Bosch throttle body injection system.
MOTRONIC − A Bosch computerized ignition and electronic fuel injection system combined into one system.
MPC (Manifold Pressure Control) − A fuel injection system that relies primarily on intake manifold pressure to signal engine load and fuel requirements.
Pulse Width − The amount of time, measured in milliseconds (one millisecond is equal to 1/1000 of a second), that the electronic fuel injector is opened for fuel distribution.
SFI (Sequential Fuel Injection) − A type of fuel injection that opens the injectors one at a time, in the same type of sequence as a spark plug firing order.
TBI(Throttle Body Injection) − Generally used to refer to any fuel injection system which uses a single point injection unit mounted on top of the throttle body, similar to a carburetor. It may have one or two injectors, and may be a high or low pressure system, depending upon application.
TPI (Tuned Port Injection) − A fuel injection system using calibrated air intake runners for equal air distribution and timed air delivery to the combustion chamber for the purpose of better performance values.