Exhaust Gas Recirculation: Testing and Inspection

1985 1C ENGINES

1. Connect vacuum gauge in line between EGR valve and VCV using a suitable fitting.
2. Start engine and ensure engine runs properly at idle. If engine runs rough or stalls check for improper seating of EGR valve.
3. With coolant temperature below 122°F run engine at 1300 RPM and observe vacuum gauge. If gauge reading is not zero, BVSV is defective.
4. Warm engine to normal operating temperature and observe gauge reading at 1300 RPM. Gauge reading should be more than 7.87 (1985, 5.31) inches Hg.
5. Gradually reduce engine speed while observing gauge. If reading does not drop to zero below 1100 RPM, check for defective VSV, speed sensor or computer.
6. Gradually increase engine speed to 5000 RPM. Vacuum reading should rise, gradually decrease to 5.31 inches Hg, then drop to zero as engine speed exceeds 5000 RPM. Do not hold engine at high RPM for extended periods of time as engine damage may occur.
7. If system fails to perform as outlined in step 8, test VRV as follows:
a. Disconnect output hose from VRV and connect gauge to valve.
b. Gradually increase engine speed from idle to 5000 RPM while observing gauge.
c. Gauge reading should gradually decrease, then drop to zero at 5000 RPM.
d. If VRV fails to perform as outlined, valve is defective.
8. If incorrect readings were obtained in step 8, but VRV performs properly, VCV is defective.