System Check
- Visually check EGR system. Replace any hoses that are cracked or broken. With engine stopped, check EGR valve operation with hand vacuum pump.
- With engine running, check EGR valve and thermal vacuum valve for normal operation. Place mirror under the diaphragm of EGR valve. When engine temperature is below 41°F (5°C), EGR valve should not operate when engine speed is increased.
- When engine temperature is above 57°F (14°C), EGR valve should operate when engine speed increases. If EGR valve is not operating properly, disconnect one end (EGR valve side) of vacuum hose which connects to the vacuum amplifier. Make sure that sub-venturi vacuum is present.
- If there is no vacuum, replace thermal vacuum valve. If there is vacuum, replace vacuum amplifier.