Evaporative Emissions System: Testing and Inspection

Purge Control System Inspection:

PURGE CONTROL SYSTEM INSPECTION (NON-TURBOCHARGED)

1. Disconnect the red striped vacuum hose from the throttle body and connect a hand vacuum pump to the hose and plug the nipple.
2. While the engine is cold (coolant temperature less than 60 degrees C or 140 degrees F) allow the engine to idle and apply 375 mm Hg or 14.8 in. Hg of vacuum and verify that vacuum holds.
3. Increase engine speed to 3,000 rpm, apply 375 mm Hg or 14.8 in. Hg of vacuum and verify that vacuum holds.
4. Allow the engine to warm up (engine coolant temperature greater than 70 degrees C or 158 degrees F).
5. With the engine operating at idle apply 375 mm Hg or 14.8 in. Hg of vacuum and verify that vacuum holds.
6. Within three minutes of engine start increase engine speed to 3,000 rpm. Attempt to apply vacuum and verify that vacuum leaks.
7. After more than three minutes have elapsed since engine start increase engine speed to 3,000 rpm, apply 375 mm Hg or 14.8 in. Hg and verify that vacuum is held momentarily and then leaks. (Note! Vacuum will leak continuously if the test is being performed at elevations greater than 2,200 m (7,200 ft.) or intake air temperature is greater than 50 degrees C or 122 degrees F.

Purge Control System Inspection:

PURGE CONTROL SYSTEM INSPECTION (TURBOCHARGED)

1. Disconnect the purge air hose from the air intake hose and plug the air intake hose.
2. Connect a hand vacuum pump to the purge air hose.
3. While the engine is cold (coolant temperature less than 60 degrees C or 140 degrees F) apply 375 mm Hg or 14.8 in. Hg of vacuum and verify that vacuum holds both while the engine is at idle and at 3,000 rpm.
4. Allow the engine to warm up (coolant temperature greater than 70 degrees C or 158 degrees F).
5. Apply 375 mm Hg. or 14.8 in. Hg of vacuum while the engine is idling and verify that vacuum holds.
6. Increase engine speed to 3,000 rpm within three minutes of engine start and verify that vacuum leaks.
7. After three minutes have elapsed since engine start increase engine speed to 3,000 rpm, apply 375 mm Hg or 14.8 in. Hg of vacuum, and verify that vacuum is held momentarily and then leaks. Note that vacuum will leak continuously if the elevation is higher than 2,200 m or 7,200 ft or if intake air temperature is greater than 50 degrees C or 122 degrees F.

Purge Port Vacuum Inspection:

PURGE PORT VACUUM INSPECTION

1. Warm up the engine until coolant temperature exceeds 85 degrees C or 185 degrees F.
2. Disconnect the vacuum hose from the throttle body purge hose nipple and connect a hand vacuum pump to the nipple.

Purge Port Vacuum vs Engine RPM:

3. Start the engine and verify that vacuum is present at the purge port and does not vary with engine rpm. If no vacuum is present the port may be clogged.

Purge Control Solenoid Valve Inspection (Leaks):

PURGE CONTROL SOLENOID VALVE INSPECTION

1. Mark and then disconnect the vacuum hoses (black, red striped) from the solenoid valve.
2. Disconnect the harness connector from the solenoid valve.
3. Connect a hand vacuum pump to the nipple the red striped hose was removed from.

Fig. 1 Purge Control Solenoid Valve Inspection (Operation):

4. Apply vacuum to the solenoid valve and verify that vacuum holds.
5. Apply 12vdc and verify that vacuum leaks.

Purge Control Solenoid Valve Inspection (Coil Resistance):

6. Measure the solenoid coil resistance and verify that it is between 36 and 44 Ohms at 20 degrees C or 68 degrees F.

Purge Control Valve Inspection, Vacuum Nipple (Turbo):

PURGE CONTROL VALVE INSPECTION (TURBOCHARGED VEHICLES ONLY)

1. Remove the purge control valve from the vehicle.
2. Connect a hand vacuum pump to the vacuum nipple of the purge control valve.
3. Apply 400 mm Hg or 15.7 in. Hg of vacuum and verify that vacuum holds.
4. Blow gently into the canister side nipple and verify that when no vacuum is apply air does not pass through the valve.
5. Apply 200 mm Hg or 8.0 in. Hg of vacuum and verify that air will pass through the valve.

Purge Control Valve Inspection, Pressure Nipple (Turbo):

6. Connect a hand vacuum pump to the positive pressure nipple of the purge control valve.
7. Apply 400 mm Hg. or 15.7 in. Hg of vacuum and verify that vacuum holds.