Pretty much the title, I been trying to fix my 4.0 in my 95 xj for a few days now. One of the injectors wasn’t connected, so I ran it for a while without it while i diagnosed it/got it home, but as soon as i got the injector hooked up again for a bit it started making this whining sound. Still makes it when i unhook the injector. Any ideas?

 

I would try taking off the belt and see if the noise goes away .and see if it is loose .