Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSTOYOTA1990TERCEL BASE, 2D COUPE, STANDARDREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCESYSTEMENGINE CONTROLS - SYSTEM/COMPONENT TESTS - 4-CYL CARBURETEDAIR SUCTION SYSTEMEGR SYSTEM TEST
1990 Toyota Tercel Base, 2D Coupe, Standard
EGR System Test
1990 Toyota Tercel Base, 2D Coupe, StandardSECTION EGR System Test
NOTE:
When diagnosing an EGR problem, refer to Figs. Fig 1, Fig 2 and Fig 3 for system components and operating parameters.
- Ensure modulator filter is clean and in good condition prior to performing test. Clean filter with compressed air as required. Disconnect vacuum hose from EGR valve.
- Using a "T" connector, connect a vacuum gauge in EGR valve vacuum line. Check that engine starts and runs at idle. This ensures proper seating of EGR valve.
- Different vacuum switching valves are used depending on model. See Fig 1, Fig 2 or Fig 3. The Bi-Metallic Vacuum Switching Valve (BVSV), Thermostatic Vacuum Switching Valve (TVSV), Vacuum Switching Valve (VSV) and EGR modulator can be checked with engine coolant below minimum temperature and specified engine RPM in accordance with application. See EGR SPECIFICATIONS table.
- 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.
- Operate engine at normal operating temperature and specified RPM. See EGR SPECIFICATIONS table for specified engine RPM. A low vacuum reading should be obtained.
- Disconnect hose from the "R" port of EGR vacuum modulator. Using additional hose, connect "R" port directly to intake manifold. High vacuum reading should be obtained at specified engine RPM. See EGR SPECIFICATIONS table.NOTE: Engine should misfire due to large amounts of exhaust gas being injected into intake manifold.
- To check EGR valve, apply vacuum directly to EGR valve with engine idling. Engine should run rough. If system did not operate as described, each component should be tested. See COMPONENT TEST in this article.
EGR SPECIFICATIONS
| Model | Minimum Temperature | Engine RPM |
|---|---|---|
| Corolla (4A-F) | 122°F (50°C) | 2000 |
| Pickup (22R) | 113°F (45°C) | 3000 |
| Tercel | 104°F (40°C) | 3000 |
RENDER: 1.0x
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.