Exhaust Gas Recirculation: Testing and Inspection

Schematic View Of EGR System Operation:

Diagnostic Chart Of EGR System Operational Conditions:

EGR SYSTEM INSPECTION
1. INSPECT AND CLEAN FILTER IN EGR VACUUM MODULATOR.



(a) Remove the cap and 2 filters.
(b) Check the filter for contamination or damage.
(c) Using compressed air, clean the filter.
(d) Reinstall the 2 filters and cap.
HINT: Install the filter with the coarser surface facing the atmospheric side (outward).

2. INSTALL VACUUM GAUGE.



- Using a 3-way connector, connect a vacuum gauge to the hose between the EGR valve and vacuum modulator.

3. INSPECT SEATING OF EGR VALVE.
- Start the engine and check that the engine starts and runs at at idle.

4. INSPECT VACUUM SWITCHING VALVE (VSV) OPERATION WITH COLD ENGINE.
(a) The coolant temperature should be below 60°C (140°F).



(b) Check that the vacuum gauge indicates zero at 3,500 rpm.

5. INSPECT VSV OPERATION WITH HOT ENGINE.
(a) Warm up the engine to above 60°C (140°F).



(b) Check that the vacuum gauge indicates low vacuum at 3,500 rpm.

6. REMOVE VACUUM GAUGE.
- Remove the vacuum gauge, and reconnect the vacuum hoses to their proper locations.

7. INSPECT EGR VALVE.



(a) Apply vacuum directly to the EGR valve with the engine idling.
(b) Check that the engine runs rough or dies.
(c) Reconnect the vacuum hoses to the proper locations.

IF NO PROBLEM IS FOUND DURING THIS INSPECTION, SYSTEM IS NORMAL; OTHERWISE INSPECT EACH SYSTEM COMPONENT.