Exhaust Gas Recirculation System (EGR)

1. Make a thorough visual check of system, wiping oil as necessary to facilitate inspection. Replace any broken or cracked hoses and ensure that electrical connectors are securely connected.
2. On non-turbocharged models, ensure EGR control valve diaphragm does not move when engine coolant temperature is below 140°F and engine speed is increased from idle to 3000-3500 RPM. The diaphragm should move when engine coolant temperature is above 140°F and engine speed is increased from idle to 3000-3500 RPM.
3. On turbocharged models, proceed as follows:
a. Disconnect EGR vacuum hose from back pressure transducer valve and ensure vacuum is present at 2000 RPM under no load.
b. Reconnect EGR vacuum hose to back pressure transducer valve, then disconnect hose from EGR control valve.
c. Ensure throttle vacuum is present when engine speed is increased from idle to 3000-3500 RPM.
d. Reconnect vacuum hose to EGR control valve.