: Strange exhaust system noise



cam30era
03-06-11, 11:25 AM
I have noticed a strange resonance that appears to be coming from the exhaust system. It only happens after a cold start. The first time you accelerate from a stop, around 1500 RPM. Only lasts about 1 second. Then it's gone, and doesn't do it again until the vehicle sits long enough for the engine to cool off (several hours). It's a low frequency, coarse sound. Definitely coming from under the vehicle, seems to be towards the back. Almost sounds like a brief exhaust "ground out".

After the brief, 1 second sound, you will not hear it again until the engine cools off.

This has me mystified that it only does it when the engine is cold, and only does it once.

Anyone else experience this?

coolbeans
03-07-11, 11:38 AM
Hi,
Yes, I was in the car yesterday, and decided to just listen to the radio while waiting for the wife, (alot of you guys know how that goes)..anyway, I noticed the exhaust note change as you stated, but I figure it's the engine system doing it's warm-up thing..(real technical sounding eh?) Kind of like the butterfly in the exhaust finally opening all the way after the engine warms up. I'm sure someone with a much more informed answer will come along shortly.

cam30era
03-07-11, 11:53 AM
Hi,
Yes, I was in the car yesterday, and decided to just listen to the radio while waiting for the wife, (alot of you guys know how that goes)..anyway, I noticed the exhaust note change as you stated, but I figure it's the engine system doing it's warm-up thing..(real technical sounding eh?) Kind of like the butterfly in the exhaust finally opening all the way after the engine warms up. I'm sure someone with a much more informed answer will come along shortly.

Thank you for the feedback. For the record, it's not really objectionable. But I noticed it and wondered if it was common to most/all vehicles, or if it was a "defect" on mine. I appreciate your response.