VandykeT/A

Ok a guy I know has 02 a4 trans am. I put a air box lid on the car that didn't have the air provisions so I simply unhooked the pump and let the hose hang we'll the next time he drove the car it had what sounded like good ol traditional rod knock after getting a few miles away from home. We'll the car will actually not knock all the time. I pulled the trans and no cracked flex plate are they any way possible that the pump just being unhooked could cause this like some how build pressure. I believe not but two others believe it's the pump since it happened right after