Silver37

I'm experiencing an unusually loud noise coming from my car only in the colder months, and only for the 1st 25 minutes I drive it each day. Here's what I know:

1) the exhaust noise is loud and makes a pulsing noise similar to how a Subaru WRX exhaust sounds. Power is fairly good when this happens, although it's hard to tell for sure with all the noise and commotion going on.
2) the sound is only present when the outside temperature is below 60 degrees F. Above that temperature, no issues.
3) the noise gets louder the colder it gets, and eventually plateaus.
4) the noise is loudest right below the driver's seat and will last for approximately 25 minutes in normal driving, then, like clockwork will clear up and everything sounds as it should. Smooth sounding and pulls great. Exhaust seems tight and nothing is loose underneath the car.
5) everything is stock, and I have good plugs, belts, oil, antifreeze, thermostat, etc.
6) everything under the hood sounds normal - I don't seem to be having any VVEL noise like I've heard on other threads.
7) this isn't the normal loud exhaust startup noise that our cars have...I'm the original owner and very used to that.
8) this is the 2nd winter this has acted up - I'm fine for the rest of the year.
9) only showing one code - U1000 which is transmission related. No engine codes to date.

Any suggestions of what to check out before running it into the dealer? Any help would be greatly appreciated.

Baby Jumpman

iTrader: (18)

Loud like what? Metal on metal? Something shaking or loose?

crookncastle

possible crack on a weld for some exhaust component or bad gasket. as the exhaust sys warms up the metal it seals the noise. hard to say since we can't hear the noise and drive the car to determine what exactly u are talking about.

Silver37

The noise is mostly a loud and rough exhaust which sounds similar to how a WRX exhaust sounds with an aftermarket exhaust. Like I'm hearing a lot of the individual exhaust strokes. I was also thinking it was a leaky exhaust, but everything looks tight. Was wondering if there's something internally wrong with a muffler or maybe something in the variable valve train set up that's making it sound that way. I've never had the "bees in a can" issue...I think that affected cars built before mine.

ANMVQ

iTrader: (13)

Sounds like an exhuast leak that seals as the metal heats and expands .

And your cold is below 60 :/, Try 24 this morning when I left for work.

Silver37

Yeah...we've had those temps down here this week, so the car noise is driving me crazier...thus the post. The 60 degree mark is just my observation over time....we've had a lot of ups and downs on cold this winter, and when it hits that mark all seems OK. Very weird but predictable.

former520

I have the exact same scenario to the T. Same location and all. I am going to bring it in to an exhaust shop to have it all tightened up/ gaskets replaced if needed.

Has happened to everything I have owned, a good shop should knock it out easily.