Chasing a flat spot

[stevieturbo]

Good result.

What is the makeup of it inside ? Is it just a restrictor ?

[JulianEdgar]

I haven't pulled it apart because I have only the one!

However, blowing through it and comparing it with the other dampers I got, the MAP sensor damper seems much more sensitive to speed of flow than the normal 'vacuum hose' dampers. For example, it has almost no restriction if blown through gently but when a quick puff of breath is forced through it, the restriction is high.

My guess is that there is some sort of mesh or gauze inside.

[stevieturbo]

Subaru's for years had some sort of solenoid in the line just before the map sensor. Not sure if it was some sort of damper or what it did really.

[Scott@FP]

http://en.wikipedia.org/wiki/Beat_%28acoustics%29

Essentially what is happening, but instead of sound amplitude, it is pressure amplitude as measured by the sensor as the engine RPM generated frequency and sensor sampling frequency coincide.