Exhaust Gas Recirculation: Testing and Inspection

EGR SYSTEM INSPECTION

1. Check and clean filter in EGR vacuum modulator.

EGR Vacuum Modulator Filter:

- 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.

3-Way Connection:

- 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.

Cold Engine Inspection:

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.

Hot Engine Inspection:

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 3,500 rpm.
- Disconnect the vacuum hose from port R of the EGR vacuum modulator and connect port R directly to the air intake chamber with another hose.
- Check that the vacuum gauge indicates high vacuum at 3,500 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.

EGR Valve Inspection:

- 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.