EGR System
- Check and clean vacuum modulator filters with compressed air before proceeding with test. On California carbureted vehicles, disconnect and plug vacuum hose at distributor main diaphragm.
- Disconnect vacuum hose from EGR valve and, using a "T" connector, connect a vacuum gauge. Check that engine starts and runs at idle.
- Check BVSV with coolant temperature below 113°F (45°C) on Camry and 86°F (30°C) on all others. Check that vacuum gauge indicates zero at 3000 RPM on carbureted vehicles, and 3500 RPM on fuel injected vehicles.
- Check BVSV and EGR vacuum modulator with engine hot. Vacuum gauge should indicate low vacuum at 3000 RPM on Federal carbureted vehicles, and 3500 RPM on fuel injected vehicles. High vacuum reading should be observed at 3000 RPM on California carbureted vehicles.
- On all except California carbureted vehicles, 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 3000 RPM on Federal carbureted vehicles, and 3500 RPM on fuel injected vehicles. 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.