2003 Odyssey Abnormal Noise During Low Speed Acceleration

I have a 2003 Odyssey. We only go around 40,000 miles on the car. Just last week, the car develped an abnormal noise during low speed acceleration. Test it on the freeway seems normal. Stop the car, put it on "P" and ramp the engine seems OK. My wife toke it back to Honda, they checked it out ( charge us $130 for looking ) and said the problem is a broken internal part of the muffler just aft the catalytic converter. They recommended to replace it parts+labor around $600. We have them order the part on Friday, however when we drove the car yesterday and today, the noise went away. If the muffer is broken, it would not fix itself. Does anyone have this experience before. Need help!

well maybe the loose metal part inside the muffler is rattling and the flow of exhaust is keeping it from making noise also 40,000 miles isnt this car still under warranty if so then you shouldnt have to pay for anything i would double check and make sure its not under warranty before paying

Some dealers will sock you with a diagnostic fee regardless of warranty or not.:banghead: I guess they have to make money some way. I know there was a TSB for a heat shield above the secondary shaft, between the exhaust and the trans. Non-rotating related noises can take some time to pinpoint.

Joel