i have a 2000 civic ex and whenever the rps get to 2700 rpm it makes a humming/ buzzing noise ONLY at that rpm in every gear. i can hold the rpm at 2700 and it doesnt stop buzzing but it goes away when i accelerate or decelerate from that rpm. does anyone know what it could be??

 

Something is resonating at that exact harmonic frequency

 

maybe the heat sheilds rattling or is your cat gutted or anything? I put a factory axle back on an aftermarket midpipe and hear and it would have an annoying ass rasp around 3k rpm

 

everthing on the exhaust is stock. it be some loose metal or something resonating? what could be some possibilities?

 

It could be anything.

I recommend having someone sit in the car, rev to that rpm and hold it while you walk around and listen

 

thanks ill try that. its not bad right now but my gf has the same problem but her's is REALLY bad and i dont want mine to get to that point.

 

your girls can is loose, wut?

 

something is resonating when she hits a certain rpm but hers sounds like her car is going to blow up. she drives a toyota rav4

 

took off the heat sheild underneath the cat. converter and the header and it still makes that noise. what else could be resonating?!

 

broken catalyst? resonator crapping out? muffler?