Cold Weather - Exhaust Question

[njswider]

Question regarding the stock exhaust with the low temps in the northeast these past couple weeks. I’ve noticed that when slowing down/coming to a stop, the exhaust note is much louder than normal as soon as it gets to 1500 RPM down to idle. Noticeably louder to the point where it sounds like I have an aftermarket system installed. Only way I can replicate is if the car is out in the teens for a bit of time. Car is garaged so it is warm when leaving in the morning but after an hour or so when getting off the highway for work it is obvious. Also happened today when car was parked outside for a few hours and temps were around 18F. I’m assuming it’s the temperature but I’m not educated enough to know what could be causing this? I do not have the flaps open full time either.

This week should be getting back to 30s or so for a few days so if it stops happening, I guess I can confirm my suspicions.

 

[tonipepperoni77]

It’s just a known thing that cold weather makes Exhausts deeper in sound. Aka Cold start scenarios


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[GTI Jake]

Engine/transmission mounts transfer more NVH when it’s cold out. It’s not really the exhaust note that’s louder

Cold start/high idle also increases the volume, but only for 30-60 seconds

 

[njswider]

The cold start example makes sense to me, I guess I’m just hesitant that after an hour drive on the highway when the car is clearly up to operating temps that this would happen. It’s a non-issue, I’m just curious.


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[tonipepperoni77]

The cold start example makes sense to me, I guess I’m just hesitant that after an hour drive on the highway when the car is clearly up to operating temps that this would happen. It’s a non-issue, I’m just curious.


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Yeah that was just an example but what happens is how the cold affects the exhaust tone in general compared to warm. No matter if the car is already warmed up but the sound the comes out in Lower temps just makes it deeper. There’s some science to it but that’s what’s happening.


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[cmgsar]

Yeah that was just an example but what happens is how the cold affects the exhaust tone in general compared to warm. No matter if the car is already warmed up but the sound the comes out in Lower temps just makes it deeper. There’s some science to it but that’s what’s happening.


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After 3 years in a cold climate my experience is flaps stay open at 15 degrees and below regardless of other variables.

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[tonipepperoni77]

After 3 years in a cold climate my experience is flaps stay open at 15 degrees and below regardless of other variables.

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The flaps do not stay open based on temperature. Our cars flaps are managed by the ECU and RPMs etc.


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[el_zorro]

Question regarding the stock exhaust with the low temps in the northeast these past couple weeks. I’ve noticed that when slowing down/coming to a stop, the exhaust note is much louder than normal as soon as it gets to 1500 RPM down to idle. Noticeably louder to the point where it sounds like I have an aftermarket system installed. Only way I can replicate is if the car is out in the teens for a bit of time. Car is garaged so it is warm when leaving in the morning but after an hour or so when getting off the highway for work it is obvious. Also happened today when car was parked outside for a few hours and temps were around 18F. I’m assuming it’s the temperature but I’m not educated enough to know what could be causing this? I do not have the flaps open full time either.

This week should be getting back to 30s or so for a few days so if it stops happening, I guess I can confirm my suspicions.

I had the same experience all last week. It was as if the soundactor was on high volume or flaps were open all the 45min ride from home to work and vice versa.

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[The Fed]

It's from the cold. It's been in the 30's and 40's here in the mornings and I also hear a noticeable difference in throatiness.

 

[vj123]

A theory behind this.
https://www.carthrottle.com/post/why-are-cold-starts-so-loud/

 

[Sasmf]

I have a 2015 R with completely stock exhaust. Car is garage kept in an unheated garage. This past 1.5 weeks in CT has been running between 5-15 F, and the car's exhaust is louder across the board, at idle all the way to redline.
There is also a very distinct burble when letting off the gas that makes it sound like an aftermarket system. Anything below 18 F and it exhibits this behavior. Several people on VWVortex have detailed the exact same experience.