Exhaust Gas RECIRCULATION (EGR) System Test
NOTE:
EGR systems contain different components and have different operating parameters depending on application. See Figure-31. When testing EGR system and components, use proper illustration to determine component location.
- Ensure EGR vacuum modulator filter(s) are clean and in good condition. Clean filter(s) with compressed air (if necessary).
- Using "T" connector, install vacuum gauge in vacuum line to EGR valve. Start engine. Ensure engine runs idles smoothly to ensure proper seating of EGR valve.NOTE: The EGR system components can be checked with engine coolant temperature less than minimum temperature and engine at specified engine RPM.
- Operate engine with engine coolant temperature less than minimum temperature and at specified RPM. See EGR TESTING SPECIFICATIONS table. No vacuum reading should be obtained.
- Warm engine to normal operating temperature. Operate engine at specified engine RPM again. See EGR TESTING SPECIFICATIONS table. Ensure a low vacuum reading is now obtained.
- Disconnect vacuum hose from port "R" of EGR vacuum modulator. See Fig 1.
- Using additional hose, connect port "R" of EGR vacuum modulator directly to intake manifold. High vacuum reading should be obtained at specified engine RPM. See EGR TESTING SPECIFICATIONS table.NOTE: Engine should misfire due to large amounts of exhaust gas being injected into intake manifold.
- Remove vacuum hose and reconnect original vacuum hose to EGR vacuum modulator.
- To check EGR valve operation, remove vacuum hose from EGR valve. Using vacuum pump, apply vacuum directly to EGR valve with engine idling. Engine should run rough or stall. If EGR system does not operate as described, each individual component should be tested.
EGR TESTING SPECIFICATIONS
| Application | Minimum Temperature | Engine RPM |
|---|---|---|
| Paseo & Tercel | 117°F (47°C) | 2500 |