#### COMPONENT TESTING

##### 2TZ-FE Engine

###### SYSTEM CHECK

Fig. 1: Exhaust Gas Recirculation (EGR) system components — 1991–92 2TZ-FE engine

Fig. 2: Exhaust Gas Recirculation (EGR) system components — 1993–95 2TZ-FE engine

1. Check and clean the filter in the EGR vacuum modulator. Use compressed air (if possible) to blow the dirt out of the filters and check the filters for contamination or damage.

   Fig. 3: Check the filter of the EGR modulator for contamination or damage

2. Using a tee (3-way connector), connect a vacuum gauge to the hose between the EGR valve and the vacuum modulator.

   Fig. 4: Place a 3-way union on the EGR valve hose, then connect a vacuum gauge it

3. Check the seating of the EGR valve by starting the engine and seeing that it runs at a smooth idle. If the valve is not completely closed, the idle will be rough.
4. Connect a tachometer as per manufactures instructions.
5. With the engine coolant temperature below 99°F (37°C), the vacuum gauge should read 0 at 2500 rpm. This indicates that the Bi-metal Vacuum Switching Valve (BVSV) (1991–92 models) or TVV (1993–95 models) is functioning correctly at this temperature range.

   Fig. 5: With the coolant level cold, inspect the vacuum gauge reading

6. Warm the engine to normal operating temperature. Check the vacuum gauge and confirm low vacuum at 2500 rpm.

   Fig. 6: Inspect the vacuum gauge readings with the engine at normal operating temperature

7. Disconnect the vacuum hose from the R port on the EGR vacuum modulator and, using another piece of hose, connect the R port directly to the intake manifold. Check that the vacuum gauge indicates high vacuum at 3500 rpm.

   NOTE: Port R is the lower of the two ports. As a large amount of exhaust gas enters, the engine will misfire slightly at this time.

8. Remove the tachometer.
9. Disconnect the vacuum gauge and reconnect the vacuum hoses to their proper locations.
10. Check the EGR valve by applying vacuum directly to the valve with the engine at idle. (This may be accomplished either by bridging vacuum directly from the intake manifold or by using a hand-held vacuum pump.) The engine should falter and die as the full load of recalculated gasses enters the engine.
11. If no problem is found with this inspection, the system is OK; otherwise inspect each part.

###### EGR VALVE

1. Remove the EGR valve.
2. Check the valve for sticking and heavy carbon deposits. If a problem is found, replace the valve.
3. Reinstall the EGR valve with a new gasket.

###### EGR VACUUM MODULATOR

1. Label and disconnect the vacuum hoses from ports P, Q, and R of the EGR vacuum modulator.

   Fig. 7: Inspecting the EGR vacuum modulator with the engine stopped

2. Plug the P and R ports with your fingers.
3. Blow air into port Q. Check that the air passes freely through the sides of the air filter.

   NOTE: Port Q is the single port on the one side of the modulator.

4. Start the engine and maintain 2500 rpm.

   Fig. 9: Inspecting the EGR vacuum modulator with the engine at 2500 rpms

5. Repeat the test above. Check that there is a strong resistance to air flow.
6. Reconnect the vacuum hoses to the proper locations.
7. If the operation is not as specified, replace the EGR vacuum modulator.

###### BIMETAL VACUUM SWITCHING VALVE (BVSV)

1. Drain and recycle the engine coolant.
2. Remove the BVSV.
3. Cool the BVSV to below 99°F (37°C) with cool water. Blow air into pipe and check that the BVSV is closed.
4. Heat the BVSV to above 133°F (56°C) with hot water. Blow air into pipe and check that the BVSV is open. If a problem is found, replace the valve.
5. Install the BVSV as per instructions.
6. Refill the cooling system with the proper amount of water coolant mixture.

###### THERMAL VACUUM VALVE (TVV)

1. Remove the TVV valve from the engine.
2. Cool the valve to below 99°F (37>deg.> C) with cool water.

   Fig. 10: Place the Thermal Vacuum Valve (TVV) into cool water while blowing air into the top port

3. Make sure that air does not flow from the upper port to the lower port.
4. Heat the TVV to above 133°F (56°C) with hot water.

   Fig. 11: Next place the TVV in hot water and apply air to the top port

5. Check that air flows from the upper port to the lower port of the valve. If the operation is not as specified, replace the TVV valve.
6. Reinstall the TVV valve.

###### EGR GAS TEMPERATURE SENSOR

1. Remove the EGR gas temperature sensor.
2. Place the sensor in a container of oil.
3. Using an ohmmeter, measure the resistance between terminals.
   - 69–89 kilohms @ 112°F (50°C)
   - 11–15 kilohms @ 212°F (100°C)
   - 2–4 kilohms @ 302°F (150°C)
4. If the resistance is not within the specifications, replace the sensor.
5. Install and secure the sensor.

   Fig. 12: Place the EGR gas temperature sensor in a container of oil and measure the resistance

##### 2TZ-FZE Engine

###### SYSTEM CHECK

1. Check and clean the filter in the EGR vacuum modulator. Remove the cap and filter, then using compressed air (if possible) to blow the dirt out of the filter and check for contamination or damage. Reinstall the filter and cap.

   NOTE: Install the filter with the coarse side facing outward.

2. Using a tee (3-way connector), connect a vacuum gauge to the hose between the EGR valve and the VSV.
3. Check the seating of the EGR valve by starting the engine and seeing that it runs at a smooth idle. Check that the EGR valve is fully seated.
4. Connect a Toyota hand-held tester or OBDII scan tool. Refer to the manufactures instructions.
5. Inspect the Vacuum Switching Valve (VSV) with the engine coolant temperature below 113°F (45°C), the vacuum gauge should read 0 at 3500 rpm.

   Fig. 13: Read the vacuum gauge between the EGR valve and modulator hoses adjoined

6. Warm the engine to normal operating temperature. Check the vacuum gauge and confirm zero vacuum at 4500 rpm.
7. Lightly race the engine and check that the vacuum gauge reads a vacuum and then returns to zero vacuum immediately.
8. Checnge the vacuum hose between the EGR valve and the EGR vacuum modulator. Warm the engine to above 122°F (50°C). Check that the vacuum gauge indicates low vacuum at 3500 rpm.
9. Disconnect the vacuum hose from the R port on the EGR vacuum modulator and, using another piece of hose, connect the R port directly to the intake manifold. Check that the vacuum gauge indicates high vacuum at 3500 rpm.

   Fig. 14: Locations of port R and Q of the vacuum modulator during testing

   NOTE: As a large amount of exhaust gas enters, the engine will misfire slightly at this time.

10. Disconnect the scan tool and vacuum gauge, then reconnect the hoses to their proper locations.
11. Check the EGR valve by applying vacuum directly to the valve with the engine at idle. (This may be accomplished either by bridging vacuum directly from the intake manifold or by using a hand-held vacuum pump.) The engine should falter and die as the full load of recalculated gasses enters the engine.
12. If no problem is found with this inspection, the system is OK; otherwise inspect each part.

###### EGR VALVE

1. Remove the EGR valve.
2. Check the valve for sticking and heavy carbon deposits. If a problem is found, replace the valve.
3. Reinstall the EGR valve with a new gasket.

###### EGR VACUUM MODULATOR

1. Connect a Toyota hand-held tester or equivalent OBD II scan tool as per manufacturer's instructions to the DLC3.

   Fig. 15: Connect the hand-held tester to the OBD II DLC3 port

2. Label and disconnect the vacuum hoses from ports P, Q from the EGR vacuum modulator and plug them.

   Fig. 16: Inspecting the EGR vacuum modulator with the engine stopped

3. Disconnect and plug port Q also. Blow air into port Q. Check that the air passes freely through the sides of the air filter.
4. Start the engine and maintain 3500 rpms.

   Fig. 17: Inspecting the EGR vacuum modulator with the engine running at 3500 rpm's

5. Repeat the test above. Check that there is a strong resistance to air flow.
6. Reconnect the vacuum hoses to the proper locations.
7. Disconnect the scan tool.

###### VACUUM SWITCHING VALVE (VSV)-AIR FILTER TYPE

The VSV is attached to the No. 2 air inlet duct. Some VSV models are equipped with an air filter at the end.

1. Check that air flows from port E to the air filter.
2. Connect the vacuum switching valve terminals to the battery.
3. Check that air flows from port E to port F.
4. If the VSV fails this test replace it. Any doubts perform the following test.
5. Remove the VSV.
6. Check for an open circuit. Using an ohmmeter, measure the resistance (ohms) between the two terminals of the valve. The resistance (cold) should be 37–44 ohms. If the resistance is not within specifications, replace the VSV.
7. Check for a short circuit within the valve. Using an ohmmeter, check that there is no continuity between the terminals and the VSV body. If there is continuity, replace the VSV.

###### VACUUM SWITCHING VALVE (VSV)-NON-AIR FILTER TYPE

1. Check that air does not flow from port E to port F.
2. Connect the vacuum switching valve terminals to the battery.
3. Check that air flows from port E to port F.
4. If the VSV fails this test replace it. Any doubts perform the following test.
5. Remove the VSV.
6. Check for an open circuit. Using an ohmmeter, measure the resistance (ohms) between the two terminals of the valve. The resistance (cold) should be 37–44 ohms. If the resistance is not within specifications, replace the VSV.
7. Check for a short circuit within the valve. Using an ohmmeter, check that there is no continuity between the terminals and the VSV body. If there is continuity, replace the VSV.

###### EGR GAS TEMPERATURE SENSOR

1. Remove the EGR gas temperature sensor.
2. Place the sensor in a container of oil.
3. Using an ohmmeter, measure the resistance between terminals.
   - 64–97 kilohms @ 112°F (50°C)
   - 11–16 kilohms @ 212°F (100°C)
   - 2–4 kilohms @ 302°F (150°C)
4. If the resistance is not within the specifications, replace the sensor.
5. Install and secure the sensor.