FUEL INJECTION CONTROL

FUEL INJECTION AMOUNT CONTROL

List of main compensations for fuel injection amount control

Compensations	Content
Maximum fuel injection amount restriction	The maximum fuel injection amount is the upper limit of the fuel injection amount that is calculated in proportion to the intake air amount obtained by the manifold absolute pressure sensor, engine coolant temperature sensor, and barometric pressure sensor. If the fuel injection amount calculated in accordance with the accelerator position and the engine speed exceeds the maximum fuel injection amount, the engine-ECU uses the maximum fuel injection amount as the proper fuel injection amount.
Engine coolant temperature compensation	When the engine is cold, this compensation is made to suit the engine coolant temperature. The lower the engine coolant temperature, the greater the fuel injection amount will be.
Small injection quantity learning compensation	This compensation is made to correct the slight variances in the fuel injection amounts between the cylinders.

SMALL INJECTION QUANTITY LEARNING

The fuel injection characteristics of the injectors and the friction resistances in the cylinders vary slightly by cylinder. Engine-ECU learns these differences and makes compensations so that the fuel injection amounts in the cylinders are uniform.

Engine-ECU uses the crank angle sensor to detect the speed for each cylinder during combustion and memorizes the cylinder differences in the form of learned values. Then, the learned values remain stored in engine-ECU memory until it is updated.

This learning takes place automatically after the vehicle travels a predetermined distance. It is normal for the engine to sound somewhat different from the ordinary during the learning process. Furthermore, it is possible to force the engine-ECU to learn through the use of the M.U.T.-III.

DRIVE TRAIN SYSTEM PROTECTION CONTROL <M/T>

To protect the drive train from extreme loads, the engine-ECU controls the fuel injection amount so that the engine speed will not exceed 3,000 r/min under the following conditions:

Transmission shift: first or reverse
Vehicle speed: 5 km/h or less

FUEL INJECTION TIMING CONTROL

List of main compensations for fuel injection timing control

Compensations	Content
Engine coolant temperature compensation	This compensation is made to suit the engine coolant temperature. The lower the coolant temperature, the more advanced the fuel injection timing will be.
Barometric pressure compensation	This compensation is made to suit the barometric pressure. The lower the barometric pressure, the more advanced the fuel injection timing will be.

Multiple Stage Injection Control

Engine-ECU injects fuel before and after the main injection to suit the driving conditions.
The injection that takes place before the main injection is called pre-injection, which is provided primarily for reducing combustion noise and NOx.
The injection that takes place after the main injection is called after-injection, which is provided primarily for activating the catalyst.