System Operational Test

EGR System Inspection:

1. Disconnect the green striped vacuum hose from the EGR valve and connect a hand vacuum pump through a vacuum "Tee".
2. While the engine is cold (coolant temperature less than 68° F or 20° C) race the engine and verify that vacuum is not present.
3. Allow the engine to warm up (coolant temperature greater than 158° F or 70° C).
4. Race the engine and verify that vacuum increases to 3.9 in. Hg (100 mm Hg) or more.
If the vacuum does not increase, the hoses may be routed incorrectly, the thermo valve may be defective or the vacuum port may be restricted.

EGR Valve Inspection:

5. Disconnect the vacuum "Tee" and connect the vacuum pump directly to the EGR valve.
6. Using the vacuum pump apply 8.5 in. Hg (215 mm Hg) of vacuum while the engine is at idle and verify that idle becomes unstable. If the engine does not respond, the EGR valve may be defective or the passage may be restricted.
7. Turn the key to the OFF position.