Just picked up our '09 EX 4-cylinder and have noticed a droning sound when cruising at 1500RPM. It’s loud, definitely noticeable buzzing noise. It seems to come through the floor, exhaust pipe or engine or transmission. I am concerned that it may be a defective muffler/resonance. Has anyone else experienced this or is it just my Accord?

i think thats from the "high flow" exhaust system the lx-s and ex has to get the extra horsepower.

No it's not just you, I kinda experience that too when the car is holding a high gear a little too long. I've found the optimum cruising rpm is around 1700, when it drops to 1400-1500 there's vibration and the engine sounds kinda weird.

my car has the same sound, especially when taking my foot off the accelerator and the grade logic control kicks in and uses the engine for braking. I enjoy the sound and grade logic a great deal. It is one of my favorite features, reminds me how sophisticated this little I-4 is.

Manual or Auto? I have a manual and i am getting the same buzzing/rattling noise in 1st gear. I can never get the dealer to hear it though...

It's ATX. The annoying noise at 1500rpm can be described as drone/resonance. I can duplicate it when the car is in P or N status. Can't endure it even if turn on the audio.

What's the reason? Exhaust system flaw? Poor assembling quality or defective muffler?

It's probably the inherent instability of I4's, just a natural design flaw shared by every I4 engine.

FYI, today dealer checked my car and adjusted the exhaust pipe. Now It's as quiet as what I would expected. I am very satisfied with the result.

Thanks for your information.

What did the dealer do to it then? Did they say what the problem was? What was the fix?

I'm experiencing the exact same thing. Any info you guys can provide would be much appreciated. Sounds almost as if the exhaust is right under my feet instead of at the rear of the car.

If it's a rattling or sounds like something is shaking because it's lose, it might be the exhaust gasket!

I took my car into today to the dealership and they said the exhaust gasket isn't right and it came from factory like that, it's right between the engine and the headers. Waited 6 hours until they figured out what was going on. Wel that's what they say anyway, I'll be getting the part installed sometime next week and I will update everyone then.

So then, likely the drove was from the muffler as the overall sound that it was trying to control wasn't what it originally was designed for because it was changed due to this leak at the manifold.

Is this the gasket at the exhaust manifold to the engine? Or is it after the manifold and on part of the exhaust pipe before the cat?

Just curious what the location is.
This may very well be the cause of another car I've seen, older Accord. If the manifold or gasket is cracked/leaking then it would change the exhaust note but might not be loud enough to hear it under the hood.

Any thoughts?