Exhaust Gas Recirculation: Testing and Inspection

EGR System Testing:

EGR SYSTEM TESTING

NOTE: Check that codes 24 or 32 are not stored before testing EGR system. Refer to ON-BOARD DIAGNOSTICS. If codes are present, refer to COMPUTERIZED ENGINE CONTROLS.

1. With ignition "ON" and engine "OFF," the electronic vacuum regulator valve (EVRV) should not be energized. Apply vacuum to intake manifold side of EVRV. No vacuum should be able to pass to the EGR valve.
2. Ground the diagnostic terminal (refer to ON-BOARD DIAGNOSTICS) and the EVRV should energize. Apply vacuum to intake manifold side of EVRV. Vacuum should now reach the EGR valve, causing it to move.
3. Start engine, warm to operating temperature and run at idle. Lift up on EGR valve and idle should become rough. If not, remove EGR valve and check passages for being plugged. Replace EGR valve if passages are clear.
4. If idle became rough in the previous step, connect a vacuum gauge to the hose at the EGR valve.
5. Place transmission in gear, hold brakes and momentarily accelerate to about 1800 rpm while observing vacuum gauge. Gauge should read over 2 inHg and less than 10 inHg. The EVRV should not be energized in park or neutral.
6. If vacuum reading is within specification, EGR system is functioning properly.
7. If vacuum is over 10 inHg, clean or replace EGR filter.
8. If vacuum is less than 2 inHg, check vacuum lines for restrictions.