Engine noise
 

‘99 Boxster Base, manual trans. I have a ‘buzzing’ noise from 3100 rpm thru 3400 rpm that comes and goes. It’s pretty subtle in volume. I haven’t been able to correlate it to any particular set of circumstances. It happens engine cold or hot. I hear it around 70% of the time. Varying the throttle makes no difference in the volume.
I’ve checked around the exhaust system and various pieces of engine sheet metal with no luck. Any suggestions? All help appreciated.
Jim

You say the volumne doesn't change, but does the frequency?

Have you tried getting someone to hold it at 3100 rpm while you go around the car and/or engine compartment to try to isolate the source?

I'll try both suggestions. Thanks!!!!!

Well, I went out to the shop today ready to make some headway against the buzzing noise only to have the car not make any sounds other than the ones we love to hear. The only thing I've changed since the first post on this problem is the battery. Now, in no way, do I think that changing the battery 'cured' the problem, but it's not there today. I drove the car more than an hour and it just sounded normal.
If the buzzing comes back, I'll do the checks suggested and report back. Thanks again for the help.
Jim

probably not very helpful but mine buzzes when it's cold, always has and owned for 3 years. Buzzing goes away once warmed up. Buzzing lasts a bit longer during colder months.

Turns out my car buzzed cause it was low on power steering fluid. Buzzing is gone.

Thanks for the follow up. I’ll check mine.

I should have titled this thread 'engine compartment noise'. As it turns out, my power steering fluid was low. No more noise.