Air Injection: Testing and Inspection

1. Disconnect air suction hose (lower hose) from anti-afterburn valve and plug it.
2. Raise and support front of vehicle, block rear wheels, and apply hand brake.
3. Remove air cleaner cover and filter.
4. Start engine and check for a bubbling noise from air suctionport at idle.
5. If there is no bubbling noise, proceed to step 11.
6. If there is a bubbling noise, disconnect hose routed from control switch at air suction cut off diaphragm.
7. If bubbling noise is still heard, replace air suction cut-off diaphragm and retest.
8. If bubbling noise stops, check for voltage at control switch solenoid valve.
9. If there is voltage, replace speed sensor and retest.
10. If there is no voltage, replace control switch solenoid valve and retest.
11. Engage transmission in second gear and accelerate above 15 mph, then suddenly release throttle and check for bubbling noise.
12. If bubbling noise is not heard, disconnect hose from air suction cut-off diaphragm valve and connect vacuum gauge to hose. Accelerate above 15 mph in second gear, suddenly release throttle, and check for vacuum.
14. If there is vacuum, check air suction line from air cleaner to exhaust manifold through air suction valve for leaks or bad connection. If hose is satisfactory, replace air suction valve and retest.
15. Remove cover from emission control box. Disconnect hose from control switch and check for vacuum during deceleration above 15 mph.
16. If there is vacuum, replace control switch and retest.
17. If no vacuum, check for voltage at control switch solenoid valve.
18. If there is voltage, check vacuum line to intake manifold for leaks, blockage, or disconnection. If hose is satisfactory, replace control switch solenoid valve and retest.
19. If there is no voltage, check wiring and fuse and, if satisfactory, replace speed sensor and retest.