EGR System Toyota Tercel L30

DESCRIPTION

The Exhaust Gas Recirculation (EGR) system is used for the reduction of NOx emissions by lowering combustion temperatures. Recycling metered amounts of exhaust gas back into the intake system lowers combustion temperatures.

Each system has a vacuum-operated EGR valve and a vacuum modulator. Temperature sensing devices control EGR operation.

Temperature sensing device used could be a Vacuum Switching Valve (VSV), a Bi-Metallic Vacuum Switching Valve (BVSV), a Thermostatic Vacuum Switching Valve (TVSV), Vacuum Control Valve (VCV) or a combination of these valves. A check valve, EGR cooler and computer may also be used on some models.

OPERATION

When engine is below operating temperature, no exhaust gas recirculation is obtained. Increase in engine temperature allows control valves to regulate vacuum to EGR valve for gas recirculation.

Vacuum modulator is used to regulate exhaust backpressure, balance atmospheric pressure and vacuum to allow EGR operation at heavy throttle. The EGR cooler, used on the Cressida and Supra assists in reducing exhaust gas temperature before entering combustion chamber.

Scheme 25

1. EGR vacuum modulator may be a 2 port or 3 port depending on application. On 2 port models, disconnect hoses from vacuum modulator. Plug one end of hose connection on EGR vacuum modulator.
2. Apply air pressure through remaining port. Air should pass freely through air filter side. On 3 port models, disconnect all hoses. Block "P" and "R" ports. Apply air pressure to "Q" port. (Scheme 25) Air should pass through the air filter side freely.
3. On all models, operate engine at specified RPM. See «EGR VACUUM MODULATOR SPECIFICATIONS»(/toyota/tercel/l30-1986-1990/remont/testing-diagnostics/#egr-system) table. Repeat previous test procedure. Strong resistance of airflow should be felt. Replace EGR vacuum modulator if resistance is not felt.

Camry (2.5L), Corolla (EFI), Corolla FX-16, MR2, Pickup (Turbo), Tercel Sedan & Van

1. Drain cooling system and remove BVSV. Using cool water, cool BVSV to below minimum temperature according to application. See «BVSV SPECIFICATIONS»(/toyota/tercel/l30-1986-1990/remont/testing-diagnostics/#egr-system) table.
2. On all models except Tercel Sedan, apply air through top port of valve. Air should not exhaust through bottom port. Heat BVSV valve to above maximum temperature according to application. See «BVSV SPECIFICATIONS»(/toyota/tercel/l30-1986-1990/remont/testing-diagnostics/#egr-system) table. Apply air in top port. Air should exhaust through lower port. Replace assembly if defective.
3. On Tercel Sedan with M/T, a 3 port BVSV is used while a 2 port is used on A/T applications. On both applications, cool BVSV to below minimum temperature. See «BVSV SPECIFICATIONS»(/toyota/tercel/l30-1986-1990/remont/testing-diagnostics/#egr-system) table.
4. On A/T models, apply air to top port of valve. Air should exhaust from lower port. On M/T models, apply air to the center port. Air should exhaust from the upper and lower ports.
5. Heat BVSV valve to above maximum temperature. See «BVSV SPECIFICATIONS»(/toyota/tercel/l30-1986-1990/remont/testing-diagnostics/#egr-system) table. On A/T models, apply air to top port. Air should not exhaust through lower port. On M/T models, apply air to the center port. Air should not exhaust through any port. Replace assembly if defective.

Camry (2.0L), Pickup (2.4L Carbureted & Non-Turbo), 4Runner (2.4 EFI) & Celica (2WD)

1. Drain cooling system and remove BVSV. Cool BVSV to minimum temperature according to application using cool water. See «BVSV SPECIFICATIONS»(/toyota/tercel/l30-1986-1990/remont/testing-diagnostics/#egr-system) table.
2. Apply air to the lower port. Air should escape from air filter located on top of valve assembly. Heat BVSV valve to maximum temperature according to application. See «BVSV SPECIFICATIONS»(/toyota/tercel/l30-1986-1990/remont/testing-diagnostics/#egr-system) table.
3. Apply air to the lower port. Air should exhaust from the upper port but not through the air filter. Replace assembly if defective.

Corolla (Carbureted), Corolla FX-16 & Tercel Wagon

1. Drain cooling system and remove TVSV. Cool TVSV to 45°F (7°C). Apply air pressure to port "J". (Scheme 28) Air should escape from ports "M" and "L".
2. Apply air pressure to port "K". Air should escape from port "N." Heat TVSV to 63-122°F (17-50°C). Apply air pressure to port "K". Air should escape from ports "N" and "L". Apply air pressure to port "J". Air should escape from port "M".
3. Heat TVSV to 154°F (68°C). Apply air pressure to port "K". Air should escape from ports "M" and "L". Apply air pressure to port "J". Air should not escape from any ports. Replace assembly if defective.

Scheme 26

Corolla (EFI), Corolla FX-16, MR2 & Supra (Turbo)

1. Connect battery to VSV terminals. (Scheme 27)- (Scheme 31). Apply air pressure to port "E". Air should escape from port "F". Disconnect battery terminals.
2. Apply air pressure to port "E". Air should now escape from air filter. Using ohmmeter, check for continuity between terminals and VSV body. Replace unit if incorrect airflow or continuity exists.
3. Using ohmmeter, measure resistance between both terminals of valve assembly. Resistance should be 38-44 ohms at 68°F (20°C) for Supra models or 33-39 ohms at 68°F (20°C) for all others. Replace valve if resistance is not within specification.

Scheme 27

Scheme 28

Scheme 29

Scheme 30

Scheme 31

Pickup & 4Runner (3.0L)

1. Connect battery to VSV terminals. (Scheme 27) Apply air pressure to port "E". Air should escape from air filter. Disconnect battery terminals.
2. Apply air pressure to port "E". Air should now escape from port "F". Using ohmmeter, check for continuity between terminals and VSV body. Replace unit if incorrect airflow or continuity exists.
3. Using ohmmeter, measure resistance between both terminals of valve assembly. Resistance should be 30-50 ohms at 68°F (20°C). Replace valve if resistance is not within specification.

Celica (4WD) & Land Cruiser

1. Apply air pressure to port "E". Air should escape from port "F". (Scheme 27) Connect battery to VSV terminals. Apply air pressure to port "E".
2. On Celica models, air should escape from air filter. On Land Cruiser models no air should escape from port "F".
3. On Celica models, using ohmmeter, check for continuity between terminals and VSV body. Replace unit if continuity exists. Using ohmmeter, measure resistance between both terminals of valve assembly. Resistance should be 33-39 ohms. Replace valve if resistance is not within specification.

Cressida

1. Connect battery to VSV terminals. (Scheme 27) Apply air pressure to port "E". Air should escape from port "F". Disconnect battery terminals.
2. Apply air pressure to port "E". Air should not flow from port "F". Using ohmmeter, check for continuity between terminals and VSV body. Replace unit if incorrect airflow or continuity exists.
3. Using ohmmeter, measure resistance between both terminals of valve assembly. Resistance should be 38-44 ohms at 68°F (20°C). Replace valve if resistance is not within specification.

Supra (Non-Turbo)

1. Connect battery to VSV terminals. (Scheme 27) Apply air pressure to port "E". Air should escape from port "F". Disconnect battery terminals.
2. Apply air pressure to port "E". Air should not escape from port "F". Using ohmmeter, check for continuity between terminals and VSV body. Replace unit if incorrect airflow or continuity exists.
3. Using ohmmeter, measure resistance between both terminals of valve assembly. Resistance should be 38-44 ohms at 68°F (20°C). Replace valve if resistance is not within specification.

Pickup (Turbo)

1. Using vacuum pump, apply 1.18 in. Hg to port "S". (Scheme 29) With vacuum applied air should be drawn in at port "Z". Remove vacuum supply.
2. Apply air pressure at port "Z". Air should escape through air filter. Replace valve assembly if defective.

Scheme 32

VACUUM CHECK VALVE

Apply air pressure to one side of check valve. Air pressure should flow easily in one direction and should not flow through valve when air pressure is reversed.

Cressida, MR2, Supra, Pickup & 4Runner (3.0L)

Disconnect coolant temperature sensor. Using ohmmeter, measure resistance in accordance with coolant temperature. (Scheme 33) Replace sensor if not within specification.

Scheme 33

JET

Blow through jet. Replace jet if airflow is restricted.

1. Ensure modulator filter is clean and in good condition prior to performing test. Clean filter with compressed air if necessary. Disconnect vacuum hose from EGR valve.
2. Using a "T" connector, connect a vacuum gauge in EGR valve line. Check that engine starts and runs at idle. This ensures proper seating of EGR valve.
3. The BVSV, TVSV, VSV and EGR modulator can be checked with engine coolant below minimum temperature and specified engine RPM in accordance with application. See «EGR SPECIFICATIONS»(/toyota/tercel/l30-1986-1990/remont/testing-diagnostics/#egr-system) table. Different valves are used depending on model. (Scheme 34)through (Scheme 49).
4. Operate engine with engine coolant below minimum temperature and specified RPM. No vacuum reading should be obtained when operated with engine coolant below minimum temperature.
5. Operate engine at normal operating temperature and specified RPM. See «EGR SPECIFICATIONS»(/toyota/tercel/l30-1986-1990/remont/testing-diagnostics/#egr-system) table for specified engine RPM. Low vacuum reading should be obtained.
6. Vacuum reading of 2.6 in. Hg should be obtained on Cressida and Supra models. On Cressida, Land Cruiser, Pickup and 4Runner (3.0L) and Supra non-turbo models, check that no vacuum is shown at idle. Also check Corolla models with EFI, Corolla FX-16 and the MR2 models at 5000 RPM. No vacuum should exist.
7. Disconnect hose from the "R" port of EGR vacuum modulator on all models except the Celica 4WD, Tercel Wagon, Pickup (turbo) and Supra (turbo) models. (Scheme 34)through (Scheme 49).
8. Using additional hose, connect "R" port directly to intake manifold. High vacuum reading should be obtained at specified engine RPM. See «EGR SPECIFICATIONS»(/toyota/tercel/l30-1986-1990/remont/testing-diagnostics/#egr-system) table. NOTE: Engine should misfire due to large amounts of exhaust gas being injected into intake manifold.
9. Disconnect vacuum gauge and install vacuum hoses. To check EGR valve, apply vacuum directly to EGR valve with engine idling. Engine should run rough. If system did not operate within specifications, each component should be tested. See «COMPONENT TEST»(/toyota/tercel/l30-1986-1990/remont/testing-diagnostics/#egr-system).

Scheme 34

Scheme 35

Scheme 36

Scheme 37

Scheme 38

Scheme 39

Scheme 40

Scheme 41

Scheme 42

Scheme 43

Scheme 44

Scheme 45

Scheme 46

Scheme 47

Scheme 48

Scheme 49

EGR SPECIFICATIONS

EGR VACUUM MODULATOR

EGR VACUUM MODULATOR SPECIFICATIONS

BVSV

BVSV SPECIFICATIONS

See also:
• EGR VACUUM MODULATOR SPECIFICATIONS