Cressida & Supra
- Check and clean vacuum modulator filters with compressed air before proceeding with test. Disconnect vacuum hose from EGR valve and, using a "T" connector, connect a vacuum gauge. Check that engine starts and runs at idle.
- Check VSV with coolant temperature below 135°F (57°C). Check that vacuum gauge indicates zero at 2500 RPM.
- Check VSV and EGR vacuum modulator with engine hot. Vacuum gauge should indicate about 3 in. Hg at 2500 RPM and zero at idle.
- 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 gauge and reconnect vacuum hoses to proper locations. Engine should run smooth. If no problem is found with this inspection, system is okay.