EFI Electronic Fuel Injection Terminology Explained
Whether you are ready to make the switch to Electronic Fuel Injection or if you are still considering the switch, there are several words and phrases that you will need to know. In this video Jason from FAST will explain some of the most common words and phrases used when talking about EFI systems.
ECU Electronic Control Unit
Electronic Fuel Injection, (or as it's more commonly called EFI) refers to the injection of fuel into the intake manifold by different types of fuel injectors, which is controlled by an ECU or Electronic Control Unit. The ECU is sometimes referred to as the box, or the computer, but basically it's the brains of an EFI system. Now let's take a look at some other terms often used in connection with EFI.
MAP Manifold Absolute Pressure
First up is MAP which stands for Manifold Absolute Pressure . The MAP Sensor measures the amount of vacuum pressure inside of a running engine. It then tells the ECU how much load is on the engine. In other words, how hard the engine is working. The information the sensor is picking up is important because the two pieces of data the ECU needs to work properly are RPM and Load.
Oxygen Sensor / 02 Sensor
Another valuable sensor in the EFI system is the Oxygen or 02 Sensor. What the 02 Sensor does is measures the air-fuel mixture in the exhaust system and correct any errors in its fuel decisions.
BPW Base Pulse Width
Up next is BPW or Base Pulse Width. Base Pulse Width is the amount of time an injector is opened by the ECU in one engine cycle. Once the ECU has calculated everything, BPW is the end result of how much fuel is actually put into the engine. If the ECU sees it needs to increase fuel, it does so by increasing Pulse Width. If it needs to decrease fuel, it decreases Pulse Width.
IDC Injector Duty Cycle
A term related to BPW is IDC or Injector Duty Cycle. IDC is the ratio of BPW compared to the total time of an engine cycle. IDC measures and indicates how much of an injectors capacity is being used in an engine. If an injector is at full capacity, it's a sure sign that the injector is too small.
IAC Idle Air Control
Another important EFI term is IAC or Idle Air Control. the IAC is an electronic valve that regulates a controlled vacuum leak. That controlled leak allows for great idle speed control and can maintain consistent idle speed under different loads. It also can raise or lower idle speed when needed.
CAN Controller Area Network
Some EFI systems are equipped with a Controller Area Network or CAN. The Controller Area Network acts as a gateway, in that it allows the devices to communicate a large amount of information over a simple high speed to wire network. Since it provides data from all sensors, it eliminates most of the extra wiring necessary on vehicles not equipped with CAN.
TCU Transmission Control Unit
One of the primary components that uses CAN is the Transmission Control Unit or TCU. The TCU is similar to the ECU in that it's a computer, but the TCU only varies transmission behaviour. Things like vehicle speed, shift points, shift firmness, down shifting and torque converter lockup are some of the variables handled by the TCU and all of this info is a result of a CAN connection.
So let's review some of the EFI related terms we've covered today: MAP Manifold Absolute Pressure, 02 Sensors, BPW which is Base Pulse Width, IDC stands for Injector Duty Cycle, IAC is Idle Air Control, CAN the Controller Area Network and last is the TCU or Transmission Control Unit. We hope that with a better understanding of Electronic Fuel Injection your EFI setup will have you cruising in no time.
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