You joined only a month ago? It sounds like you suggested changes too quickly. Egos may be hurt by the new guy saying "you're doing everything wrong."

Poltics goes a long way in this. You need to make others happy first and build up some goodwill first. If you want to tough it out here, do this first, make some allies, and then slowly suggest changes.

Don't suggest to everyone at once, try to build consensus for your changes one engineer at a time. Ideally you'd make friends with the lead or others you can pitch to first privately.