HONDA Anti-AFTERBURN Valve: Testing

Remove air cleaner cover, then start engine and allow to idle. Place finger over air inlet tube and check for vacuum. There should be no vacuum.
- If there is no vacuum, proceed to next step.
- If vacuum is felt, replace anti-afterburn valve and repeat test.
Quickly raise engine speed to 3500 RPM and close throttle quickly. Again check for vacuum at inlet tube. There should be vacuum as throttle closes.
- If vacuum is felt, valve is okay.
- If vacuum is not felt, locate restriction or blockage and retest.
- If vacuum is still not felt, replace anti-afterburn valve and retest.
Fig 1: Testing Anti-Afterburn Valve
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Use finger to check for vacuum.