VACUUM MODULATOR
- Disconnect vacuum hoses from ports "P", "Q" and "R" of vacuum modulator. Plug ports "P" and "R" (2 ports on same side) and blow through port "P" (single port on opposite side). Air should escape freely from filter.
- Start engine and run at 2000 RPM on Camry and 3000 RPM on Celica. Repeat blowing test. There should be strong resistance to air flow through modulator. If not, replace modulator. Reconnect vacuum hoses to proper locations.
BI-METALLIC VACUUM SWITCHING VALVE (BVSV)
- Drain coolant and remove BVSV valve. Place sensing portion in cool water, but do not allow water into valve.
- Cool BVSV to below 113°F (45°C) on Camry and below 86°F (30°C) on Celica. Blow air into bottom port and check that air escapes through filter.
- Heat BVSV to above 150°F (66°C) on Camry and above 111°F (44°C) on Celica. Blow air into bottom port and check that air escapes through top port.
- Apply liquid sealer to threads of BVSV and reinstall. Fill radiator with coolant. If problem is found, replace BVSV.
Scheme 37
- 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 BVSV with coolant temperature below 113°F (45°C) on Camry and 86°F (30°C) on Celica. Check that vacuum gauge indicates zero at 2500 RPM on Camry and 3500 RPM on Celica. (Scheme 37): EGR System (Celica)
- Check BVSV and EGR vacuum modulator with engine hot. Vacuum gauge should indicate low vacuum at 2500 RPM on Camry and 3500 RPM on Celica.
- 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 on Camry and 3500 RPM on Celica. 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.