On my '87 GTi there is a vacuum hose that starts at the bottom side of the short plastic boot attached to the throttle body and ends up connected to a nipple on the cylinder head. Does anyone know what this vacuum hose is for?
Also, on my car someone has carved a small (about 2 mm dia.) hole at the elbow of this hose. It most certainly is done deliberately as there is nothing even close to rubbing against that spot. I'll happily take suggestions on what the purpose of this hole might be.