FUEL INJECTION AMOUNT CONTROL OPERATION [MZR-CD (RF Turbo)]

BME014000140T42

• The fuel injection amount is controlled in accordance with the length of the injection pulse.

Injection Amount Calculation

• The PCM calculates the optimal injection amount according to the engine driving condition. The following two injection amount are calculated.
• The values of the two amounts below are compared, and the lesser amount is selected as the final injection amount.

Basic injection amount

• The theoretical necessary injection amount is calculated based on the accelerator opening angle and the engine speed.

Maximum injection amount

• The maximum injection amount is calculated by adding the corrections based on intake air pressure and intake air temperature to the basic injection amount.

Injection Amount Learning

• To confirm the dispersion of the fuel injection amount, the PCM calculates the change in engine speed.
• Based on the change in engine speed, the PCM confirms the fuel injection amount in each cylinder and increases or decreases that amount in order to smooth engine operation. The amount of increase or decrease is stored as the learning factor and used to correct the fuel injection amount. Due to this, the dispersion of the fuel injection amount is resolved.
• The PCM stores the learning factor until the next time the factor is updated.
• Injection amount learning is performed at the following three pressure levels in the common rail.

.

1
Learning start
2
One time period of learning
3
Learning completion
4
Common rail pressure (MPa {kgf/cm2, psi})
5
Time (seconds)

• When carrying out injection amount learning, slight changes in engine sound are normal.

Automatic learning

• The PCM carries out injection amount learning every 1,500 km within the first 6,000 km of driving and every 10,000 km after that, when the following conditions are satisfied at idle:
- Gear is in neutral position.
- Vehicle speed is 0 km/h {0 mph}.
- Engine coolant temperature is 65°C {104°F} or above.
- A/C is not operating.
• Three learning cycles occur during automatic learning.
• If any of these conditions change while carrying out injection amount learning, the process will be suspended. It will continue when the conditions are once again satisfied.
• Due to the priority ranking of the learning function, injection amount learning is given a lower priority than MAF learning. If both injection amount and MAF learning can occur at the same time, MAF learning will be performed first, followed by injection amount learning.

Using the WDS or equivalent for learning

• By using the WDS or equivalent, the learning function can be freely controlled. Due to this, even if the PCM or fuel injector is replaced, the learning factor can be stored again.
• Three learning cycles occur during periodic inspection and four learning cycles after replacing fuel injectors.