Part 1
2UZ-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: EVAP System
EVAP System
RELATED DTCS
If any EVAP system DTCs are set, the malfunctioning area can be determined using the table below.
NOTE: If the 0.02 inch leak criterion difference between the first and second checks is greater than the specification, the DTCs corresponding to the 0.02 inch leak criterion (P043E, P043F, P0441, P0455, P0456, P2401 and P2420) will all be stored.
DESCRIPTION
NOTE: In this vehicle's EVAP system, turning ON the vent valve does not seal off the EVAP system. To check for leaks in the EVAP system, disconnect the air inlet vent hose and apply pressure from the atmosphere side of the canister.
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.
1. Key-off monitor
This monitor checks for Evaporative Emission (EVAP) system leaks and canister pump module malfunctions. The monitor starts 5 hours* after the ignition switch is turned OFF. More than 5 hours are required to allow the fuel to cool down to stabilize the Fuel Tank Pressure (FTP), thus making the EVAP system monitor more accurate.
The leak detection 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 canister pump module and purge VSV, based on the EVAP pressure.
HINT: *: If the engine coolant temperature is not below 35°C (95°F) 5 hours after the ignition switch is turned OFF, the monitor check starts 2 hours later. If it is still not below 35°C (95°F) 7 hours after the ignition switch is turned OFF, the monitor check starts 2.5 hours later.
2. Purge flow monitor
The purge flow monitor consists of the two monitors. The 1st monitor is conducted every time and the 2nd monitor is conducted if necessary.
- The 1st monitor
While the engine is running and the purge Vacuum Switching Valve (VSV) 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 turned ON (closed) 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.
HINT: *: If the engine coolant temperature is not below 35°C after 5 hours after the ignition switch is turned off, the monitor check starts 2 hours later. If it is still not below 35°C 7 hours after the ignition switch is turned off, the monitor check starts 2.5 hours later.
WIRING DIAGRAM
INSPECTION PROCEDURE
NOTE: The Techstream is required to conduct the following diagnostic troubleshooting procedure.
HINT:
- Using the Techstream monitor results enables the EVAP system to be confirmed.
- Read freeze frame data using the Techstream. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air/fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction.
PROCEDURE
1. CONFIRM DTC
(a) Turn the ignition switch OFF and wait for 10 seconds.
(b) Turn the ignition switch ON.
(c) Turn the ignition switch OFF and wait for 10 seconds.
(d) Connect the Techstream to the DLC3.
(e) Turn the ignition switch ON.
(f) Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
(g) Confirm DTCs and freeze frame data.
If any EVAP system DTCs are set, the malfunctioning area can be determined using the table below.
NOTE: If the 0.02 inch leak criterion difference between the first and second checks is greater than the specification, the DTCs corresponding to the 0.02 inch leak criterion (P043E, P043F, P0441, P0455, P0456, P2401 and P2420) will all be stored.
NEXT -- Continue to next step.
2. PERFORM EVAP SYSTEM CHECK (AUTO OPERATION)
NOTICE:
- The Evaporative System Check (Automatic Mode) consists of five steps performed automatically by the Techstream. It takes a maximum of approximately 18 minutes.
- Do not perform the Evaporative System Check when the fuel tank is more than 90 % full because the cut-off valve may be closed, making the leak check of the fuel tank not possible.
- Do not run the engine in this step.
- When the temperature of the fuel is 35°C (95°F) or more, a large amount of vapor forms and any check results become inaccurate. When performing the Evaporative System Check, keep the temperature below 35°C (95°F).
(a) Clear the DTCs DTC Check / Clear.
(b) Enter the following menus: Powertrain / Engine and ECT / Utility / Evaporative System Check / Automatic Mode.
(c) After the Evaporative System Check is completed, check for pending DTCs by entering the following menus: Powertrain / Engine and ECT / Trouble Codes / Pending.
HINT: If no pending DTC is displayed, perform the CONFIRMATION DRIVING PATTERN. After this confirmation, check for pending DTCs. If no DTC is displayed, the EVAP system is normal.
NEXT -- Continue to next step.
3. PERFORM EVAP SYSTEM CHECK (MANUAL OPERATION)
NOTICE:
- In the Evaporative System Check (Manual Mode), the series of 5 Evaporative System Check steps are performed manually by the Techstream.
- Do not perform the Evaporative System Check when the fuel tank is more than 90 % full because the cut-off valve may be closed, making the leak check of the fuel tank not possible.
- Do not run the engine in this step.
- When the temperature of the fuel is 35°C (95°F) or more, a large amount of vapor forms and any check results become inaccurate. When performing the Evaporative System Check, keep the temperature below 35°C (95°F).
(a) Clear the DTCs DTC Check / Clear.
(b) Enter the following menus: Powertrain / Engine and ECT / Utility / Evaporative System Check / Manual Mode.
NEXT -- Continue to next step.
4. PERFORM EVAP SYSTEM CHECK (STEP 1/5)
(a) Check the EVAP pressure in step 1/5.
Result:
*: These DTCs are already present in the ECM when the vehicle arrives and are confirmed in step 1.
B -- REPLACE CANISTER ASSEMBLY
A -- Continue to next step.
5. PERFORM EVAP SYSTEM CHECK (STEP 1/5 TO 2/5)
(a) Check the EVAP pressure in step 1/5 and 2/5.
Result:
*: These DTCs are already present in the ECM when the vehicle arrives and are confirmed in step 1.
HINT: The first 0.02 inch leak criterion is the value determined in step 2/5.
B -- PERFORM ACTIVE TEST USING TECHSTREAM (FOR LEAK DETECTION PUMP)
A -- Continue to next step.
6. PERFORM EVAP SYSTEM CHECK (STEP 2/5)
HINT: Make a note of the pressures checked in the steps below.
(a) Check the EVAP pressure 4 seconds after the leak detection pump is activated* [A}.
(b) Check the EVAP pressure again when it has stabilized. This pressure is the 0.02 inch leak criterion [B}.
*: The leak detection pump begins to operate as step 1/5 proceeds to step 2/5.
Result:
*: These DTCs are already present in the ECM when the vehicle arrives and are confirmed in step 1.
D -- PERFORM ACTIVE TEST USING TECHSTREAM (FOR VENT VALVE)
C -- REPLACE CANISTER ASSEMBLY
B -- PERFORM EVAP SYSTEM CHECK (STEP 3/5)
A -- Continue to next step.
7. PERFORM EVAP SYSTEM CHECK (STEP 2/5 TO 3/5)
(a) Check the EVAP pressure in step 3/5.
Result:
*: These DTCs are already present in the ECM when the vehicle arrives and are confirmed in step 1.
C -- REPLACE CANISTER ASSEMBLY
B -- PERFORM ACTIVE TEST USING TECHSTREAM (FOR VENT VALVE)
A -- Continue to next step.
8. PERFORM EVAP SYSTEM CHECK (STEP 3/5)
(a) Wait until the EVAP pressure change is less than 0.1 kPa (0.75 mmHg) for 30 seconds.
(b) Measure the EVAP pressure and record it.
HINT: A few minutes are required for the EVAP pressure to become saturated. When there is little fuel in the fuel tank, it takes up to 12 minutes.
NEXT -- Continue to next step.
9. PERFORM EVAP SYSTEM CHECK (STEP 4/5)
(a) Check the EVAP pressure in step 4/5.
Result:
*: These DTCs are already present in the ECM when the vehicle arrives and are confirmed in step 1.
C -- PERFORM ACTIVE TEST USING TECHSTREAM (PURGE VSV)
B -- CHECK EVAP HOSE (PURGE VSV - INTAKE MANIFOLD)
A -- Continue to next step.
10. PERFORM EVAP SYSTEM CHECK (STEP 5/5)
(a) Check the EVAP pressure in step 5/5.
(b) Compare the EVAP pressure in step 3/5 and the second 0.02 inch leak criterion (step 5/5).
Result:
*: These DTCs are already present in the ECM when the vehicle arrives and are confirmed in step 1.
B -- PERFORM ACTIVE TEST USING TECHSTREAM (PURGE VSV)
A -- REPAIR OR REPLACE PARTS AND COMPONENTS INDICATED BY OUTPUT DTCS
11. PERFORM EVAP SYSTEM CHECK (STEP 3/5)
(a) Check the EVAP pressure in step 3/5.
Result:
*: These DTCs are already present in the ECM when the vehicle arrives and are confirmed in step 1.
HINT: The first 0.02 inch leak criterion is the value determined in step 2/5.
B -- PERFORM ACTIVE TEST USING TECHSTREAM (FOR LEAK DETECTION PUMP)
A -- REPLACE CANISTER ASSEMBLY
12. PERFORM ACTIVE TEST USING TECHSTREAM (PURGE VSV)
(a) Enter the following menus: Powertrain / Engine and ECT / Active Test / Activate the VSV for EVAP Control.
(b) Disconnect the hose (connected to the canister) from the purge VSV.
(c) Turn the ignition switch ON.
(d) Using the tester, turn the purge VSV OFF (EVAP VSV: OFF).
(e) Use your finger to confirm that the purge VSV has no suction.
(f) Using the tester, turn the purge VSV ON (EVAP VSV: ON).
(g) Use your finger to confirm that the purge VSV has suction.
Result:
C -- CHECK EVAP HOSE (PURGE VSV - INTAKE MANIFOLD)
B -- INSPECT PURGE VSV
A -- Continue to next step.
13. CHECK FUEL CAP
(a) Check that the fuel cap is correctly installed.
(1) Tighten the fuel cap until a few click sounds are heard.
HINT: If an EVAP tester is available, use the tester to check the fuel cap.
(b) Remove the fuel cap and install it onto the fuel cap adaptor.
(c) Connect an EVAP tester hose to the adaptor, and pressurize the cap to 3.2 to 3.7 kPa (24 to 28 mmHg) using an EVAP tester.
(d) Seal the adaptor and wait for 2 minutes.
(e) Check the pressure. If the pressure is 2 kPa (15 mmHg) or more, the fuel cap is normal.
(f) Reinstall the fuel cap.
Result:
C -- REPLACE FUEL CAP
B -- CORRECTLY REINSTALL OR REPLACE FUEL CAP
A -- LOCATE EVAP LEAK
14. INSPECT PURGE VSV
(a) Turn the ignition switch OFF.
(b) Disconnect the V2 purge VSV connector.
(c) Disconnect the hose (connected to the canister) from the purge VSV.
(d) Start the engine.
(e) Use your finger to confirm that the purge VSV has no suction.
Result:
(f) Reconnect the purge VSV connector.
B -- REPLACE PURGE VSV
A -- REPLACE ECM