EGR System
- Check and clean vacuum modulator filters with compressed air before proceeding with test. Using a 3-way connector, connect a vacuum gauge to the hose between EGR valve and EGR vacuum modulator.
- Check seating of EGR valve by starting engine. Engine should start and run at idle.
- Check BVSV with coolant temperature below 86°F (30°C). Vacuum gauge should indicate low vacuum at 2500 RPM.
- Warm engine to normal operating temperature. Vacuum gauge should indicate low vacuum at 2500 RPM.
- Disconnect vacuum hose from port "R" of EGR vacuum modulator and connect port directly to intake manifold vacuum. Vacuum gauge should indicate high vacuum at 2500 RPM. Disconnect vacuum gauge and reconnect hoses to proper locations.NOTE: This will cause slight engine misfire due to a large amount of exhaust gas being injected into intake manifold.
- With engine idling, apply vacuum directly to EGR valve. Engine should run rough or die. Remove vacuum and reconnect vacuum hoses to proper locations. Engine should run smooth. If no problem is found with this inspection, system is okay.
- Check computer control of vacuum switching valve (VSV). Disconnect vacuum hoses from ports "E" and "F" of VSV. See Fig 2. With engine idling, blow into port "F". The valve should close and not allow air to escape through port "E".
- Increase engine speed to above 1500 RPM. Again blow into port and note that valve should open to allow air to escape from port "E". If no problem is found with this inspection, system is okay.