EGR Gas Flow Test

Fig. 3 EGR Tube Stud Bolts:

NOTE: All tests must be made with fully warm engine running continuously for at least two minutes.

Use the following procedure to 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 Hg.
- Engine speed may drop quickly or engine may even stall. This indicates that EGR gas is flowing through the system -- proper operation.
- If engine speed does not drop off when performing the EGR Gas Flow Test, remove both the EGR valve and EGR tube and check for plugged passages. Check and if necessary, clean these components for restoration of proper flow. Replace as necessary.

If the EGR Gas Flow Test, System Inspection & Test and EGR Diagnosis Chart are all completed satisfactorily, then the EGR system is functioning normally.