Dr18 - Checking EGR Function
- Disconnect vacuum line at EGR backpressure valve that comes from throttle body or solenoid. Connect a vacuum gauge to line from throttle body or solenoid. Start engine. Disconnect AIS motor. When engine reaches normal operating temperature, raise engine speed to 2500 RPM. If vacuum gauge reads at least 5 in. Hg vacuum, note reading and go to next step. If vacuum gauge reads less than 5 in. Hg vacuum or zero, repair vacuum supply from throttle body or solenoid.
- With engine running, disconnect vacuum gauge and connect vacuum hose to backpressure valve. Disconnect vacuum line from EGR valve and connect a vacuum gauge to line. Raise engine speed to 2500 RPM. If vacuum gauge reads the same or near the same as in step 1), go to next step. If vacuum gauge is not reading the same or near the same as in step 1), replace EGR/backpressure valve assembly.
- Connect a vacuum pump to EGR valve. With AIS motor disconnected and engine idling, slowly apply vacuum. If engine speed begins to drop when vacuum reaches 2.5-3.5 in. Hg vacuum, go to next step. If engine speed does not drop, replace EGR/backpressure valve assembly.
- Apply 10 in. Hg vacuum to EGR valve. If vacuum holds without bleeding for at least 10 seconds, go to DR20. If vacuum bleeds down before 10 seconds, replace EGR/backpressure assembly.