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 95°F (35°C). Vacuum gauge should indicate low vacuum at 3500 RPM.
- Warm engine to normal operating temperature. Vacuum gauge should indicate low vacuum at 3500 RPM. Gauge should read zero at 5000 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 3500 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.