What could cause white smoke from tailpipe and knocking noises in engine in a 1999 grand am?
Is the white smoke steam or oil vapor? If it's steam, it just needs to warm up, if it's oil vapor it's probably pretty serious. Same with the knocking. It could be timing or it could be a rod bearing or any of a number of potential problems that fall somewhere between the two in severity; it all depends on what it sounds like.