Impreza - Air Suction Valve Noise

Some SUBARU IMPREZA'S are equipped with air suction valves (ASV). These valves may make some noise for brief periods of time during initial cold start up and driving. They sound very much like lifter noise.

This condition is considered to be a NORMAL OPERATING CONDITION and NO REPAIRS should be made. We should also remember that this is an emission control device and can not be legally tampered with.

The noise reported usually shows up at ambient temperatures of approximately 40 degrees F. or lower with engine speeds of 2,000 RPM's or higher. The noise may go away during this time if your foot is removed from the gas pedal and may return if the throttle is again applied. Once the engine has warmed up slightly, the noise goes away and will not return again until the engine has had an extended cool down period. Usually overnight.

If you have a customer complaining of a noise in his engine when cold. it may very well be the ASV'S that are causing the noise. Question the owner about when the noise is there and how the vehicle is being operated before attempting any repairs.

If you have any questions concerning this matter, contact the Technical Helpline.