PURGE CONTROL OPERATION [L3 R.H.D.]

BUE014000000N33

Purge Solenoid Valve Operation Principle

1
Single cycle
2
Energization time

• The PCM operates the purge solenoid valve using duty signals. The duty signal uses a given frequency to vary the energization period of the purge solenoid valve during a single cycle and the length of this period determines the valve opening angle.

Determination of purge solenoid valve energization time

• The PCM determines the target purge flow amount according to engine operation conditions as the basic flow amount. Actual operation may be slowed due to delayed rise of the coil inductance operation current, or due factors such as the weight of the needle valve and plunger, and spring resistance. Energization time is corrected according to battery voltage fluctuation to compensate for such factors. The lower the rate of battery positive voltage, the longer the energization time.

Calculation method for purge flow amount

• The PCM determines the purge flow amount through the addition of each correction to the basic purge flow amount.

Contents

Calculation or determination method of purge flow amount and correction

Basic purge flow amount
The basic purge flow amount is determined by multiplying the intake air temperature correction to the purge mass volume, calculated by multiplying the base purge rate and the intake air mass volume, which differs according to engine conditions.
Correction
Purge startup correction
Purpose: Prevents a sudden change in air/fuel ratio during the startup of evaporative purge control
During evaporative purge control startup
• When evaporative purge control operation conditions are met→correction
Volume decrease correction
Purpose: Decreases the amount of purge flow amount and stabilizes the air/fuel ratio
When the fuel injection control feedback correction value is unstable
• According to HO2S feedback condition

Operation condition

• The evaporative purge control during normal driving is performed when all of the following conditions are met, and the PCM sends a duty signal to the purge solenoid valve.
- Fuel injection control is in the feedback zone.
- Airflow circuit malfunction related DTC is not stored.
- Engine coolant temperature 70°C {158°F} or more