EGR Gas Flow Test

NOTE: The following procedure should be used determine if exhaust gas is flowing through the EGR system.

1. Connect a hand vacuum pump to the EGR valve vacuum motor.
2. With engine running at idle speed, slowly apply vacuum.
- Engine speed should begin to drop when applied vacuum reaches 2.0 to 3.5 inches.
- Engine speed may drop quickly or engine may even stall. This indicates that EGR gas is flowing through the system.

If both the EGR Gas Flow Test, System Test and Diagnosis Chart are completed satisfactory, then the EGR system functions normally.

If engine speed does not drop off when performing the test, remove both the EGR valve and EGR tube and check for plugged passages. Also, check the intake manifold inlet passage. Clean or replace these components to restore proper flow.