Exhaust Gas Recirculation: Testing and Inspection

EXHAUST GAS RECIRCULATION (EGR) SYSTEM INSPECTION

1. Check and clean filter in Exhaust Gas Recirculation Vacuum Modulator.

Exhaust Gas Recirculation (EGR) Modulator Components:

a. Check the filter for contamination or damage.
b. Using compressed air, clean the filter.

Testing The Exhaust Gas Recirculation (EGR) Modulator:

2. Using a 3-way connector, connect a vacuum gauge to the EGR valve vacuum hose as shown in the illustration.

3. Check seating of EGR valve. Start the engine and check that the engine starts and runs at idle.

4. Check VSV with cold engine.






a. The engine coolant temperature should be below 47°C (117°F).
b. Check that the vacuum gauge indicates zero at 2,500 rpm.

5. Check VSV and EGR vacuum modulator with hot engine.






a. Warm up the engine.
b. Check that the vacuum gauge indicates low vacuum at 2,500 rpm.
c. Check that the vacuum gauge indicates zero at idle.






d. Disconnect the vacuum hose from port R of the EGR vacuum modulator and connect port R directly to the intake manifold with another hose.
e. Check that the vacuum gauge indicates high vacuum at 2,500 rpm.

HINT: As EGR gas is increasingly recirculated, the engine will start to misfire.

f. Disconnect the vacuum gauge and reconnect the vacuum hoses to the proper locations.

6. Check EGR valve.

Checking The VSV And EGR Vacuum Modulator:

a. Disconnect the vacuum hose from the EGR valve.
b. Apply vacuum directly to the EGR valve with the engine idle.
c. Check that the engine runs rough or stops.
d. Reconnect the vacuum hoses to the proper locations.

If no problem is found during this inspection, the system is normal; otherwise inspect each part.