Exhaust Gas Recirculation: Testing and Inspection

1. CHECK AND CLEAN FILTER IN EGR VACUUM MODULATOR
- Remove the cap and filter.
- Check the filter for contamination or damage.
- Using compressed air, clean the filter.
- Reinstall the filter 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 EGR vacuum modulator.
3. INSPECT SEATING OF EGR VALVE
- Check that the engine starts and runs at idle.





4. INSPECT VSV OPERATION WITH COLD ENGINE
- The engine coolant temperature should be below 45°C (113°F).
- Check that the vacuum gauge indicates zero at 2,500 rpm.
- Check that the EGR pipe is not hot.





5. INSPECT OPERATION OF VSV AND EGR VACUUM MODULATOR WITH HOT ENGINE
- Warm up the engine to above 50°C (122°F).
- Check that the vacuum gauge indicates low vacuum at 2,500 rpm.
- Disconnect the vacuum hose from port R of the EGR vacuum modulator and connect port R directly to the intake manifold with another hose.
- Check that the vacuum gauge indicates high vacuum at 2,500 rpm.

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

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





7. INSPECT EGR VALVE
- Apply vacuum directly to the EGR valve with the engine idling.
- Check that the engine runs rough or dies.
- Reconnect the vacuum hoses to their proper locations.
IF NO PROBLEM IS FOUND DURING THIS INSPECTION, SYSTEM IS NORMAL; OTHERWISE INSPECT EACH PART.