EGR Function Testing Toyota Tercel L20

VACUUM MODULATOR

1. Disconnect vacuum hoses from both ports of vacuum modulator. Plug port nearest EGR valve and blow air into port farthest from EGR valve. Air should escape freely through air filter of modulator.
2. Start engine and maintain engine speed at 3000 RPM. Repeat blow test. There should be strong resistance to air flow. If not, replace vacuum modulator. Reconnect vacuum hoses to proper locations.

THERMOSTATIC VACUUM SWITCHING VALVE (TVSV)

1. Drain coolant from radiator and remove TVSV. Place threaded end of valve in container of ice water with thermometer. With temperature below 45°F (7°C), check that air flows from port "J" to ports "L" and "M" and from port "K" to port "N". (Scheme 25)
2. Heat water to 63-122°F (17-50°C). Check that air flows from port "K" to ports "N" and "L" and from port "J" to port "M".
3. Continue heating water to above 154°F (68°C). Check that air flows from port "K" to ports "M" and "L" and does not flow from port "J" to any other port.
4. Apply liquid sealer to threads of TVSV and reinstall. Fill radiator with coolant. If problem is found, replace TVSV.

Testing Thermostatic Vacuum Switching Valve (TVSV). Scheme 25

CHECK VALVE

Disconnect vacuum hoses and remove valve. Blow through valve. Air should flow from Orange side to Black side, but not from Black to Orange. Replace valve if it does not perform as outlined.

Scheme 26

1. 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.
2. Check TVSV with coolant temperature below 122°F (50°C). Check that vacuum gauge indicates zero at 3000 RPM. (Scheme 26): EGR System
3. Check TVSV and EGR vacuum modulator with engine hot. Vacuum gauge should indicate low vacuum at 3000 RPM.
4. 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.