I have a 92 maxima se 5speed and heres whats going on. I just replaced all of my fuel injectors and its running like a beauty. Like a week or two after my car was finally running on 6 cylinders this noise poped up. It sounds like worn bearings or a loose pulley or something? It also only makes this noise when you acclerate!! Any suggestions on what to look for?? Im going to take a video now so you can hear what it sounds like.

 

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i know it sounds very very rare but you might wanna check your harmonic balancer. i have seen some that come loose in the middle and they look like they are still all in tact but it really is slipping itself. idk how to explain it and i know it might confuse you but you never know

 

Try a mechanics stethoscope.