Air Injection: Testing and Inspection

NOTE: On California models, this test must be performed on cold engine.

1. Disconnect air suction lower hose from anti-afterburn valve and plug hose.
2. Remove air cleaner cover and filter.
3. Start engine and check for bubbling noise from air suction port at idle.

NOTE: If working with hot engine on Federal models, check for bubbling noise within 3 minutes after starting engine.

4. If bubbling noise is not heard, proceed to step 11.
5. If bubbling noise is not heard, check for voltage at air suction control solenoid valve.
6. If there is no voltage, refer to "Troubleshooting, 1983 Prelude."
7. If there is voltage, disconnect vacuum hose No. 5 from air suction cut-off diaphragm.
8. If there is no vacuum at hose, check for leaks or disconnected hose.
9. If hoses are satisfactory, replace air suction control solenoid valve and repeat test.
10. If there was vacuum at hose, replace air suction cut-off diaphragm and repeat test.
11. Raise engine speed above 3150 RPM.
12. If bubbling noise is now heard, check for voltage at air suction control solenoid valve.
13. If there is voltage, refer to "TROUBLESHOOTING 1983 Prelude."
14. If there is no voltage, replace air suction control solenoid valve and repeat test.


TROUBLESHOOTING 1983 PRELUDE

1. On 1983 models, inspect control switch as follows:
a. Push voltmeter positive probe into gray wire terminal at connector of emissions control box No. 1 and connect negative probe to suitable ground.
b. Start engine and check for voltage during deceleration.
c. If there is no voltage, disconnect vacuum hose No. 2 from emission control box No. 1 and check for vacuum.
d. If there is no voltage, check for leaks, blockage, or disconnected hose, correct as necessary, and repeat test.
e. If there is vacuum, check vacuum line for leaks in emissions control box No. 1.
f. If vacuum line is satisfactory, replace control switch and repeat test.
2. turn ignition switch on and check for voltage at blue wire at control unit connector. If there is no voltage, check blue wire between ignition coil and control unit.
3. On 1983 models, test air suction vacuum switch as follows:
a. Disconnect vacuum hose to vacuum switch and connect vacuum pump to hose.
b. Apply vacuum to vacuum switch and check for voltage at vacuum switch.
c. Voltage should be available under conditions sown, Fig. 72.
d. If there is no voltage, replace vacuum switch and repeat test.
4. Test or 15 mph speed sensor as outlined under "Speed Sensor, Test" procedure.
5. Test thermosensor as follows:
a. Ensure that engine is cold by disconnecting vacuum hose No. 19 at charcoal canister. There must be no vacuum at idle.
b. Disconnect connector at control unit.
c. Check resistance between blue/yellow and white/black terminals on 1983-84 models or blue/yellow and brown/black terminals on 1985-86 models. Resistance should be above 1k ohm.
d. Run engine until it reaches normal operating temperature, then check resistance again. Resistance should be approximately 200 ohms.
e. If resistance is not within specifications, replace thermosensor and repeat test.
f. If ohmmeter shows no continuity, check wires.
g. If wires are satisfactory, replace thermosensor and repeat test.
6. Turn ignition switch on and check for voltage at black/yellow wire at control unit connector. If there is no voltage, check wiring.
7. Check black or brown/black wire for continuity between control unit and suitable ground. There should be no continuity.
8. On 1984-86 models, test intake air temperature switch as follows:
a. Disconnect intake air temperature switch electrical connector, then check continuity between terminals.
b. Continuity should not be present if air temperature is above 73 degrees F. Continuity should be present if air temperature is below 40 degrees F. Replace sensor as required.
9. On 1984-86 models, inspect vacuum switches for proper operation.
10. If no faults are found in steps 1 through 9, replace control unit and repeat test.