Except California
SYSTEM TESTNOTE: When disconnecting the vacuum hoses, mark or label them to ensure proper routing when reconnecting.
EGR System Vacuum Test:
COLD ENGINE TEST - Coolant temperature is below 40°C (104°F)
1. Disconnect the green striped vacuum hose from the throttle body and connect it to a hand vacuum pump.
2. Plug the nipple at the throttle body from which the hose was removed.
3. With the engine idling, try applying vacuum.
Vacuum should LEAK.
WARM ENGINE TEST - Coolant temperature is above 80°C (176°F)
1. Disconnect the green striped vacuum hose from the throttle body and connect it to a hand vacuum pump.
2. Plug the nipple at the throttle body from which the hose was removed.
3. With the engine idling, apply 1.8" vacuum.
Vacuum should hold and engine rpm should not be affected .
4. Increase vacuum to 8.5"
Vacuum should hold but the engine rpm should change to slightly unstable.
If there is no change in the engine rpm, it is possible that the passages or the valve may need to be cleaned.
Refer to MAINTENANCE PROCEDURES for EGR SYSTEM cleaning.
THERMO VALVE TEST
Testing The Thermo Valve:
1. Disconnect the vacuum hoses from the thermo valve, and connect a hand vacuum pump to a nipple of the thermo valve.
2. When the engine coolant temperature is below 50°C (122°F), vacuum applied to the valve should LEAK.
3. When the engine coolant temperature has reached 80°C (176°F) or more, the vacuum applied to the valve should HOLD.
EGR CONTROL VACUUM SUPPLY
EGR Control Vacuum Test:
1. Disconnect the vacuum hose from the throttle body EGR vacuum nipple and connect a hand vacuum pump or gauge to the nipple.
2. Start the engine. Gradually increase the engine rpm. Vacuum from the EGR nipple should increase proportionately with the engine rpm.
NOTE: If vacuum cannot be measured or does not change with the engine rpm, ensure that the hose is connected to the proper port. If so, the EGR port may be plugged and should be cleaned.
EGR VALVE TEST
EGR Valve Test:
1. Remove the EGR valve and check it for sticking or carbon deposits.
If such condition exists, refer to MAINTENANCE PROCEDURES for EGR Control Valve and Passages cleaning.
2. Connect a hand vacuum pump to the EGR vacuum nipple.
If there is more than one nipple, the second nipple will need to be plugged for this test.
3. Apply 19.8" vacuum to the vacuum chamber of the EGR valve.
Vacuum should NOT leak. Release vacuum.
4. Apply 1.8" of vacuum. Blow air in from one side of the valve.
Air should not pass through
5. Increase vacuum to 8.5" while blowing air through EGR passage.
Air should pass through.