EGR Gas Flow Test

EGR Mounting:

NOTE: Vehicle must pass CONTROL SYSTEM TEST and GAS FLOW TEST to pass EGR functional test.

1. Connect tachometer.
2. Disconnect and plug vacuum hose from EGR valve and connect hand-operated vacuum pump to EGR valve nipple.
3. Start engine and allow to warm up to normal operating temperature.
4. Slowly apply vacuum to EGR valve.
5. Engine rpm should drop as vacuum reaches 2 to 3.5 in. Hg vacuum, and should continue to drop as more vacuum is applied, engine may even stall. This drop in rpm means that EGR gas is flowing through the system (proper operation).
6. Successful completion of this test and the functional test indicates a fully-operational EGR system.
7. If engine rpm does not drop when vacuum is applied to the EGR vacuum diaphragm, then a defective EGR valve or plugged EGR passage, or tube is indicated. The EGR valve, intake manifold passage, and tube assembly should be removed, inspected, and cleaned or replaced.

NOTE: If EGR system is functioning correctly, and CHECK Engine lamp indicates malfunction of EGR system, check on-board diagnostic system.