P043F
DTC P043F EVAPORATE EMISSION SYSTEM REFERENCE ORIFICE HIGH FLOWDTC SUMMARY
HINT: The 0.02 inch orifice is located inside the pump module.
CIRCUIT DESCRIPTION
While the engine is running, if a predetermined condition (closed loop, etc.) is met, the purge VSV is opened by the ECM and stored fuel vapors in the canister are purged to the intake manifold. The ECM changes the duty cycle ratio of the purge VSV to control purge flow volume.
The purge flow volume is also determined by the intake manifold pressure. Atmospheric pressure is allowed into the canister through the vent valve to ensure that the purge flow is maintained when the negative pressure (vacuum) is applied to the canister.
The following two monitors run to confirm appropriate EVAP system operation.
Key-off monitor
This monitor checks for EVAP (Evaporative Emission) system leaks and pump module malfunctions. The monitor starts 5 hours (±15 minutes) after the ignition switch is turned to OFF. 5 hours are required to allow enough time for the fuel to cool down to stabilize the Fuel Tank Pressure (FTP), thus making the EVAP system monitor more accurate.
The electric vacuum pump creates negative pressure (vacuum) in the EVAP system and the pressure is measured. Finally, the ECM monitors for leaks from the EVAP system, and malfunctions in both the pump module and purge VSV, based on the EVAP pressure.
Purge flow monitor
The purge flow monitor consists of the two monitors. The 1st monitor is always conducted every time and the 2nd monitor is activated if necessary.
- The 1st monitor
While the engine is running and the purge VSV (Vacuum Switching Valve) is ON (open), the ECM monitors the purge flow by measuring the EVAP pressure change. If negative pressure is not created, the ECM begins the 2nd monitor.
- The 2nd monitor
The vent valve is turned OFF (open) and the EVAP pressure is then measured. If the variation in the pressure is less than 0.5 kPa (3.75 mmHg), the ECM interprets this as the purge VSV being stuck closed, and illuminates the MIL and sets DTC P0441 (2 trip detection logic).
Atmospheric pressure check:
In order to ensure reliable malfunction detection, the variation between the atmospheric pressures, before and after conduction of the purge flow monitor, is measured by the ECM.
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INSPECTION PROCEDURE
NOTE: A hand held tester is required to conduct the following diagnostic troubleshooting procedure.
HINT:
- Using hand held tester monitor results enables the EVAP (Evaporative Emission) system to be confirmed.
- Read freeze frame data using a hand held tester or OBD II scan tool. Freeze frame data record the engine condition when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air fuel ratio was lean or rich, and other data, from the time the malfunction occurred.
MONITOR DESCRIPTION
Malfunction Detection Conditions:
5 hours after the ignition switch is turned to OFF, the electric vacuum pump creates negative pressure (vacuum) in the EVAP (Evaporative Emission) system. The ECM monitors for leaks and actuator malfunctions based on the EVAP pressure.
P043F: 0.02 inch orifice high-flow
In operation B, the vacuum pump creates negative pressure (vacuum) through the 0.02 inch orifice. The EVAP system pressure is then measured by the ECM using the pressure sensor to determine the 0.02 inch leak pressure standard. If the pressure is higher than -1.2 kPa (-9.0 mmHg)*, the ECM interprets this as a high-flow malfunction in the 0.02 inch orifice, and stops the EVAP system monitor. The ECM then illuminates the MIL and sets the DTC (2 trip detection logic).
OBD II MONITOR SPECIFICATIONS
Monitor Strategy:
Typical Enabling Conditions:
Typical Malfunction Thresholds:
MONITOR RESULT (MODE 06 DATA)
Using the Monitor Result enables the EVAP system condition to be confirmed on a hand held tester. To check the system condition using a hand held tester, select the following menu items: DIAGNOSIS / ENHANCED OBD II / MONITOR INFO / MONITOR RESULT / EVAP MONITOR. INCMP, PASS and FAIL will be displayed on the EVAP MONITOR screen:
- INCMP: Monitor is incomplete. If this is displayed, repeat the Monitor Confirmation, and then reconfirm the Monitor Result.
- PASS: System is normal.
- FAIL: System malfunctions. If this is displayed, select the monitor item and press the ENTER button. VAL (Test Value) of the item is showed. If the VAL is negative, the monitor item is malfunctioning. Alternatively, if it is positive the item is normal.