Exhaust Gas Recirculation: Testing and Inspection

INSPECTION





1. Inspect and clean filter in exhaust gas recirculation 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 exhaust gas recirculation valve and exhaust gas recirculation vacuum modulator.
3. Inspect seating of exhaust gas recirculation valve.
- Start the engine and check that the engine starts and runs at idle.





4. Inspect vacuum switching valve operation with cold engine.
- The engine coolant temperature should be below 47°C (117°F).
- Check that the vacuum gauge indicates zero at 2,500 rpm.





- Check that the exhaust gas recirculation pipe is NOT hot.





5. Inspect operation of vacuum switching valve and exhaust gas recirculation vacuum modulator with hot engine.
- Warm up the engine to above 53°C (127°F).
- Check that the vacuum gauge indicates low vacuum at 2,500 rpm.





- Disconnect the vacuum hose port R of the exhaust gas recirculation 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 a large amount of exhaust gas enters, the engine will misfire slightly.





6. Remove vacuum gauge.
- Remove the vacuum gauge, and reconnect the vacuum hoses to the proper locations.
7. Inspect exhaust gas recirculation valve.
- Apply vacuum directly to the exhaust gas recirculation valve with the engine idling.
- Check that the engine runs rough or dies.
- Reconnect the vacuum hoses to the proper locations.
8. If no problem is found with this inspection, system is normal; otherwise inspect each part.