Exhaust Gas Recirculation: Testing and Inspection

EGR SYSTEM INSPECTION

1. Inspect and clean filter in EGR vacuum modulator.





- Remove the cap and 2 filters.
- Check the filter for contamination or damage.
- Using compressed air, clean the filter.
- 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 idle.

4. Inspect VSV operation with cold engine.
- The coolant temperature should be below 50°C (122°F).
- From idle, race the engine to 3,500 - 4,000 rpm (throttle valve opening angle to about 1/3 of maximum).
- Check that the EGR pipe is not hot.
- Check that the vacuum gauge indicates zero.

5. Inspect VSV operation with hot engine.
- Warm up the engine to above 50°C (122°F).
- From idle, race the engine to 3,500 - 4,000 rpm (throttle valve opening angle to about 1/3 of maximum).
- Check that the vacuum gauge indicates low vacuum.

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