This is essentially what the pressure waves would be... mild compression waves would travel outward as you pull a cylinder creating a vacuum. You've compressed

This is essentially what the pressure waves would be... mild compression waves would travel outward as you pull a cylinder creating a vacuum. You've compressed the entire atmosphere slightly, then you let some air expand back in through a small nozzle to fill the cylinder again. Then you open a port and push the air back out without changing it's volume, and close the port to complete the cycle... It seems like there's got to be something wrong with the concept, but I can't put my finger on what exactly.