Carbureted Corolla & Tercel
- 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 TVSV with coolant temperature below 122°F (50°C). Check that vacuum gauge indicates zero at 2000 RPM on FWD Corolla and 3000 RPM on RWD Corolla and Tercel.
- Check TVSV and EGR vacuum modulator with engine hot. Vacuum gauge should indicate low vacuum at 2000 RPM on FWD Corolla and 3000 RPM on RWD Corolla and Tercel.
- On FWD Corolla, 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 2000 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.
- On all models, 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.