Fuel Delivery and Air Induction: Description and Operation

EFI System:

Fuel is supplied under constant pressure to the fuel injectors by an electric fuel pump. The Injectors inject a metered quantity of fuel to the intake manifold at the intake ports and is therefore called Ported or Multi-point Fuel Injection (MFI).

The Electronic Fuel Injection (EFI) is controlled by the Toyota Computerized Control System (TCCS) which utilizes an Electronic Control Unit (ECU) to determine injection duration necessary for optimum air/fuel ratio. The ECU receives signals from various sensors that indicate changing engine operating conditions such as:

Intake Air Volume
Intake Air Temperature
Coolant Temperature
Engine RPM
Acceleration/Deceleration
Vehicle Speed
Exhaust Oxygen Content
Emission Reduction Devices

The sensors of the TCCS and ECU are covered in detail under COMPUTERIZED ENGINE CONTROLS.