Why is CT4 BW exhaust system hot on one side ?

[Chuck99]

I’m looking at a 2025 CT4 Blackwing automatic. I drove the car & have a question about the exhaust.

The dealer (not a Cadillac one) sent me some photos of the underside. One is taken with a thermal camera which shows some hot sections of the exhaust system.

The system does not appear symmetrical comparing both sides.

There’s a pipe that goes around each side of the differential. The one on the passenger side appears a bit larger & is hot according to the thermal image. The other side doesn’t even look warm.

The same for around the transmission. The passenger side has a hot section that is 2 to 3 times bigger in length than the other side.

Is this normal? Is the muffler being restricted at idle in order to make it quieter?

Thanks for any information.

 

[Kawman]

I would guess that has to do with the exhaust valves. When the car starts in regular mode the exhaust gases are flowing through one area, then hit the V-mode button opening the valves and the hot exhaust gases flow through a different area of the system.

 

[Chuck99]

I can't find anything on how the valves work or where they are located. It just seems weird that sometimes one side of the exhaust would get used more than the other. Wouldn't that create more back pressure in half of the cylinders?

 

[Todd]

Any CEL or codes in the ECU? If not, I wouldn’t sweat it. No way such a massive engine issue could be happening without setting a CEL.

Valves selectively are controlled, both fully open/closed and partially open/closed with drive mode, cold start, etc.

Mostly in the service of almighty emissions.

 

[Chuck99]

Here's the photo showing one side hot.

 

[ellteefour]

I wonder if both pipes are actually hot, but the FIR image is somehow affected by the "hot" side being clamped instead of flanged like the cooler looking side for some reason? There also appears to be something going on post x-pipe too.

Image from a Craigslist ad for a 2026:

 

[sps4runner]

I wonder how long the engine was off in that image. Did one side cool off faster than the other due to breeze, fan, A/C? Notice how the claps are hotter as if they're holding the heat longer. The pipes would warm up faster when started and cool off quicker. What is the threshold for the color shading on the thermal camera? Depending on settings, there might not be much temp difference...

 

[Chuck99]

I went to the dealer & they use a high-tech device called UVEYE to take pictures all around the car including the under body. They drive the car through the machine, Sort of like doing a CT Scan.

UVeye - The MRI for Cars

They did an appraisal on my possible trade in & one exhaust pipe is hotter than the other. The picture is called a rust view & the dealer sales person does not know the technology used. I’m guessing most of the staff is not going to know either. But it sure looks like a thermal image.

That one pipe on the right side of my car sits about a half inch lower than the left side. You can see this if viewing from behind the car. It’s been that way since new.

I’m presuming since it’s closer to a thermal camera it would display hotter than the other side. I’m guessing that’s what happening with the CT4 Blackwing.

Here’s a photo of my Charger.