Exhaust Gas Recirculation System

Inspection

PROCEDURE

1. If you suspect the system is faulty, disconnect the hoses from the EGR valve, backpressure valve and thermal vacuum valve and blow them out. If the hoses are not clogged, reconnect them.

2. For thermal vacuum valve checks, refer to item 2 of subsection 6.4.2.3.

3. To check the EGR valve, disconnect the vacuum hose from the top of the valve and connect another hose to the valve fitting. Draw air through the hose; check that the valve diaphragm lifts and quickly returns when you stop drawing air. The diaphragm movement can be checked by touching the underside of the valve with your finger. If the diaphragm moves stiffly or does not move at all, replace the EGR valve.

4. If you are sure the thermal vacuum valve is serviceable, the backpressure valve can be checked as follows. Warm up the engine to normal operating temperature and disconnect the vacuum hose from the EGR valve. Close the disconnected hose opening with your finger and briefly increase engine speed. When engine speed (and exhaust back pressure) increases, vacuum should be present in the hose. When engine speed drops, the backpressure valve should stop vacuum from reaching the hose. If not, the valve is faulty and must be replaced.

All models with fuel injection system

5. The EGR system can be checked as described in items 1–4, skipping the information on the thermal vacuum valve. A control solenoid valve is installed together with the thermal vacuum valve on these models. This solenoid valve is the same valve that controls the evaporative emission control system, and it can be checked as described in items 2–5 of subsection 6.4.2.3.