EGR CONTROL OPERATION [MZR-CD (RF Turbo)]

BME014000000T40

EGR Valve Operation

• To improve emission performance, target EGR valve position is decided based on intake air flow, engine speed and engine coolant temperature.
• The flow amount of the EGR is calculated from the difference between the following amounts.
- Target intake air amount that is mainly calculated from engine speed and fuel injection amount
- Actual intake air amount that is mainly detected by MAF/IAT sensor
• The PCM controls the vacuum applied to the EGR valve by opening and closing a two-duty solenoid valve.

Intake Shutter Valve Operation

Close condition

• The PCM turns on the intake shutter solenoid valve (half) and the intake shutter solenoid valve (full) in order to close the intake shutter valve when the engine switch is at OFF.

Halfway open condition

• The PCM turns the intake shutter solenoid valve (half) on when all of the following conditions are met.
- Engine coolant temperature is above threshold level.
- Intake air temperature is threshold level.
- Barometric pressure is above threshold level.
- Engine speed is below threshold level.
- Vehicle speed is below threshold level.

Full open condition

• For conditions other than closed and halfway open, the PCM turns off the intake shutter solenoid valve (half) and the intake shutter solenoid valve (full) in order to open the intake shutter valve.

MAF Learning

• After learning is initiated, the PCM calculates the actual intake air amount for the complete learning period.
• The PCM calculates the deviation between the target and actual intake air amount, then, based on the deviation, derives the learning factor. The PCM stores the learning factor and uses it to correct the intake air amount. Due to this, the error margin of the MAF sensor is resolved. If the deviation factor is less than the specified amount, the PCM does not calculate nor update the learning factor.
• The PCM stores the learning factor until the next time the factor is updated. However, if the negative battery cable is disconnected, the factor is erased.

Automatic learning

• The PCM carries out MAF 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.
• If any of these conditions change while carrying out MAF 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, MAF learning is given a higher priority than injection amount learning. If both MAF and injection amount 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 MAF/IAT sensor is replaced, the learning factor can be stored again.
• When using the WDS to control the MAF learning function, learning is performed at the following three engine speed levels.
- 775 rpm
- 1,100 rpm
- 1,500 rpm