Federal

With engine at operating temperature, (coolant temperature greater than 80 degrees C or 176 degrees F) rev engine and verify that EGR valve diaphragm moves.
If no movement is found, proceed to step 1.

EGR System Inspection:

1. Disconnect the vacuum hose (green strip) from the throttle housing nipple and connect a manual vacuum pump and gauge to the hose.
2. While the engine is cold (coolant temperature less than 50 degrees C or 122 degrees F) verify that when suddenly accelerating the engine from idle, there is no vacuum present.
3. Allow the engine to warm up (coolant temperature greater than 85 degrees C or 185 degrees F) and verify that while the engine is idling 6 kPa (2 in. Hg) of vacuum can be applied and held without affecting engine idle.
4. Apply 26 kPa (7.5 in. Hg) of vacuum and verify that engine idle becomes slightly unstable.
5. If system fails any of these tests, verify vacuum at throttle body, inspect hoses for leaks and repair or replace as needed. Refer to the following component tests for further testing.
Thermo Valve
EGR Valve