Exhaust Gas Recirculation: Testing and Inspection

INSPECTION

1. Check and clean filter in the Exhaust Gas Recirculation (EGR) Vacuum Modulator.





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





2. Disconnect the vacuum hose from the EGR Valve and using a three-way union, connect a vacuum gauge to it.
3. Check seating of EGR Valve.
- Start the engine and check that the engine starts and runs at idle.
4. Check Vacuum Switching Valve (VSV) 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. Check VSV and EGR Vacuum Modulator with warm engine.
- Warm up the engine.
- Check that the vacuum gauge indicates zero at idle.





- 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.

NOTE: As a large amount of EGR gas enters, the engine will misfire slightly.

- Disconnect the vacuum gauge and reconnect the vacuum hoses to the proper locations.
6. Check 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 the proper locations.

If no problems are found with this inspection, the system is normal; otherwise inspect individual components as needed.