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Home >> Nissan-Datsun >> 1996 >> 240SX L4-2.4L (KA24DE) >> Repair and Diagnosis >> Powertrain Management >> Emission Control Systems >> Evaporative Emissions System >> Testing and Inspection >> Component Tests and General Diagnostics >> System Test Procedures

System Test Procedures




ON BOARD DIAGNOSIS LOGIC
This diagnosis uses two methods to detect leaks in the EVAP purge line.
The first method, the pressure test, makes use of vapor pressure in the fuel tank. The second method, the vacuum test, makes use of engine intake manifold vacuum.

Pressure test
The EVAP canister vent control valve is closed to shut the EVAP purge line. The vacuum cut valve bypass valve will then be opened to clear the line between the fuel tank and the EVAP canister purge control valve. The EVAP control system pressure sensor can now monitor the pressure inside the fuel tank.
If pressure increases, the ECM will check for leaks in the line between the vacuum cut valve and EVAP canister purge control valve. If no pressure does not increase, the ECM will perform the "Vacuum test".

Vacuum test
If pressure does not increase in the "Pressure test", the ECM will check for leaks in the line between the fuel tank and EVAP canister purge control valve, under the following "Vacuum test" conditions.
The vacuum cut valve bypass valve is opened to clear the line between the fuel tank and the EVAP canister purge control valve. The EVAP canister vent control valve will then be closed to shut the EVAP purge line off. The EVAP canister purge volume control valve and EVAP canister purge control valve are opened to depressurize the EVAP purge line using intake manifold vacuum. After this occurs, the EVAP canister purge control valve and EVAP canister purge volume control valve will be closed.

CAUTION:
- Use only a genuine fuel filler cap as a replacement. If an incorrect fuel filler cap is used, the MIL may come on.
- If the fuel filler cap is not tightened properly, the MIL may come on.
- Use only a genuine rubber tube as a replacement.




DIAGNOSTIC TROUBLE CODE CONFIRMATION PROCEDURE

CAUTION: Always select "SINGLE TEST" with CONSULT when performing the "FUNCTION TEST".




WITH CONSULT
(1) Select "EVAP (SMALL LEAK)" in "FUNCTION TEST" mode with CONSULT.
(2) Make sure that "OK" is displayed with "EVAP (SMALL LEAK)". (If "NG" is displayed, refer to "DIAGNOSTIC PROCEDURE".)
(3) Check fuel filler cap and fuel tank when the fuel tank is more than 3/4 full.

OVERALL FUNCTION CHECK
Use this procedure to check the overall function of the EVAP control system (Small leak). During this check, a DTC might not be confirmed.

NOTE: Prepare one-way valve (Part No. 14958 V6700) for this test.

WITH NO TOOLS
(1) Turn ignition switch "OFF".
(2) Completely fill fuel tank.




(3) Set up one-way valve (Part No. 14958 V6700), pressure gauge and suitable pump as shown at left. Pressurize the system to 13.3 kPa (100 mmHg, 3.94 inch, 1.93 psi). Measure the amount of depressurization in kPa (mmHg, inch) after one minute with the system left unattended.




(4) Apply 12 volts DC to EVAP canister vent control valve. The valve will close. (Continue to apply 12V until the end of test.)




(5) Apply 12 volts DC to vacuum cut valve bypass valve. The valve will open. (Continue to apply 12V until the end of test.)




(6) Disconnect rubber tube between vacuum cut valve and EVAP shut valve. Set up one-way valve (Part No. 14958 - V6700), pressure gauge and suitable pump as shown at left.
(7) Increase system pressure until gauge registers 13.3 kPa (100 mmHg, 3.94 inch, 1.93 psi). [If pump is rated at a discharge volume of 0.13e (1/8 US qt, 1/8 Imp qt) for one operating stroke, it is capable of increasing pressure to 13.3 kPa (100 mmHg, 3.94 inch, 1.93 psi) with approximately 60 operating strokes. If pressure does not increase at all during the test, diagnosis will be ineffective ("NG")].

CAUTION: Do not allow pump pressure to exceed 13.3 kPa (100 mmHg, 3.94 inch, 1.93 psi). A higher pressure may damage fuel tank and EVAP canister.

(8) Make sure that after one minute the amount of pressure recovery is within the following.

The measured amount in step 3 + 4.51 kPa (33.87mmHg, 1.333 inch, 0.654 psi).

(9) Check fuel filler cap and fuel tank.










DIAGNOSTIC PROCEDURE

COMPONENT INSPECTION
EVAP canister purge volume control valve
WITH CONSULT
1. Disconnect EVAP canister purge volume control valve harness connector.




2. Check resistance between the following terminals.
terminal (2) and terminals (1), (3)
terminal (5) and terminals (4), (6)

Resistance: Approximately 3O Ohms [At 25°C (77°F)]

3. Reconnect EVAP canister purge volume control valve harness connector.
4. Remove EVAP canister purge volume control valve from intake manifold collector and disconnect hoses from the valve.
(Plug the purge hoses. The EVAP canister purge volume control valve harness connector should remain connected.)
5. Turn ignition switch "ON".




6. Perform "PURG VOL CONT/V" in "ACTIVE TEST" mode with CONSULT. Check that EVAP canister purge volume control valve shaft moves smoothly forward and backward according to the valve opening.
If NG, replace the EVAP canister purge volume control valve.

OR

WITH NO TOOLS
1. Disconnect EVAP canister purge volume control valve harness connection
2. Check resistance between the following terminals.
terminal (2) and terminals (1), (3)
terminal (5) and terminals (4), (6)

Resistance: Approximately 3O Ohms [At 25°C (77°F)]

3. Reconnect EVAP canister purge volume control valve harness connector.
4. Remove EVAP canister purge volume control valve from intake manifold collector and disconnect hoses from the valve.
(Plug the purge hoses. The EVAP canister purge volume control valve harness connector should remain connected.)




5. Turn ignition switch "ON" and "OFF". Check that EVAP canister purge volume control valve shaft moves smoothly forward and backward according to the ignition switch position.
If NG, replace the EVAP canister purge volume control valve.




EVAP canister purge control solenoid valve




Check air passage continuity.




If NG, replace solenoid valve.

EVAP canister purge control valve
Check EVAP canister urge control valve as follows:




1. Blow air in port (A), (B) and (C), and check that there is no leakage.
2. Apply vacuum to port (A). [Approximately -13.3 to -20.0 kPa (-100 to -150 mmHg, -3.94 to -5.91 inch)]
Blow air in port (C) and check that it flows freely out of port (B).

EVAP canister vent control valve




Check air passage continuity.




If NG, clean valve using air blower or replace as necessary.

Absolute pressure sensor
1. Remove absolute pressure sensor from bracket with its harness connector connected.




2. Remove hose from absolute pressure sensor.
3. Turn ignition switch "ON" and check output voltage between terminal (2) and engine ground.

The voltage should be 3.2 to 4.8 V.

4. Use pump to apply vacuum of -26.7 kPa (-200 mmHg, -7.87 inch, -3.87 psi) to absolute pressure sensor as shown in figure and check the output voltage.

The voltage should be 1.0 to 1.4 V lower than the value measured in step 3.

CAUTION:
Always calibrate the vacuum pump gauge when using it.

5. If NG, replace absolute pressure sensor.

MAP/BARO switch solenoid valve
WITH CONSULT
1. Start engine and warm it up sufficiently.
2. Perform "MAP/BARO SW/V" in "ACTIVE TEST" mode with CONSULT.
3. Check the following.




- When "MAP" is selected, "ABSOL PRES/SE" indicates approximately 1.3V.




- When "BARO" is selected, "ABSOL PRES/SE" indicates approximately 4.3V.
4. If NG, replace solenoid valve.

OR

WITH NO TOOLS
1. Remove MAP/BARO switch solenoid valve.




2. Check air passage continuity.




3. If NG, replace solenoid valve.

Tank fuel temperature sensor




Check resistance as shown in the figure.




If NG, replace tank fuel temperature sensor.
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