Deceleration Valve: Testing and Inspection

COLD ENGINE

1. Ensure that coolant temperature is below 158 deg. F.
2. Disconnect air suction lower hose at anti-afterburn valve.
3. Start engine and quickly raise engine speed to 3500 RPM on 1983 models and 2500 RPM on 1984-86 models, then quickly close throttle.
4. If there is no vacuum, proceed to step 11.
5. If there is vacuum, check for voltage at anti-afterburn control solenoid valve.
6. If there is no voltage on Prelude models, refer to"Troubleshooting, 1983-86 Prelude." If there is no voltage on Accord models, check for continuity between speed sensor and thermosensor wire terminals. If continuity is not present, replace thermosensor. If continuity is still not present, replace speedometer/speed sensor.
7. If there is voltage, disconnect vacuum hose from anti-afterburn valve and check for vacuum at hose.
8. If there is no vacuum, check for leaks or disconnected hose.
9. If hoses are satisfactory, replace anti-afterburn control solenoid valve and repeat test.
10. If there was vacuum in step 7, replace anti-afterburn valve and repeat test.
11. Raise and support from of vehicle, block rear wheels and apply parking brake.
12. Place shift lever in second or "2" position and accelerate, then quickly release throttle and check for vacuum during deceleration above 15 mph on all models.
13. If there is vacuum, perform hot engine test.
14. If there is no vacuum, check for voltage at anti-afterburn control solenoid valve above 15 mph.
15. If there is voltage on Prelude models, refer to "TROUBLESHOOTING, 1983-86 Prelude." If there is voltage on Accord models, replace speed sensor.
16. If there is no voltage, disconnect vacuum hose from anti-afterburn valve and check for vacuum above 15 mph on all models.
17. If there i vacuum, replace anti-afterburn control valve and repeat test.
18. If there is no vacuum, disconnect vacuum hose from anti-afterburn valve and check for vacuum at hose.
19. If there is no vacuum, check for leaks or disconnected hose and repeat test.
20. If there is vacuum, replace anti-afterburn valve and repeat test.
21. For 1983 California models, test secondary air supply system.
22. For all vehicle, perform hot engine test.

HOT ENGINE

1. Ensure that coolant temperature is above 158 deg. F.
2. Disconnect air suction lower hose at anti-afterburn valve.
3. Start engine and quickly raise engine speed to 3500 RPM, then quickly close throttle.
4. If there is no vacuum, check for voltage at anti-afterburn control solenoid valve.
5. If there is voltage on Prelude models, refer to "TROUBLESHOOTING 1983-86 Prelude." If there is voltage on Accord models, replace thermosensor.
6. If there is no voltage, replace anti-afterburn control solenoid valve and repeat test.

TROUBLESHOOTING 1983-84 PRELUDE

NOTE: If necessary to test Speed Sensor, proceed to SPEED SENSOR, TEST

1. Test thermosensor as follows:
a. Ensure that engine is sufficiently cold by disconnecting hose No. 19 at charcoal canister. There must be no vacuum at idle.
b. Disconnect connector at control unit.
c. Check for resistance between blue/yellow and white/black terminal 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.
2. Turn ignition switch on and check for voltage at black/yellow wire at control unit connector. If there is no voltage, checkwiring.
3. On 1983-84 models, ensure black wire shows continuity between control unit and suitable ground.
4. On 1985-86 models, ensure brown/black wire shows continuity between control unit and suitable ground.
5. If no faults are found replace control unit and repeat test.