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Received this comment on the blog and reposting here for discussion:

My 2011 STS pipes are always black. I have 40,205 miles on my car. Dealer states it is normal. I am a woman and don’t know what to do because it is thick. When I wash the car and clean it out it will return. Any ideal what this could be? The car seems to run hard to me but dealer said it is normal.

Bruce

2016 Cadillac ATS-V gray/black

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Please explain what you mean by "RUN HARD"

Is it a V8 or V6?

Can you take a picture of the exhaust to show what you mean??

Mine stay sorta black but it is not THICK...

Is there another Cadillac dealer close to you??

if there ism take it to them and see if they will diagnose it for you.

Since it is still under warranty, you need to get it fixed ... (assuming something is wrong with it)...before it is runs out of warranty.

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I would agree. It should not be blowing black smoke. Can you be more soecific. If it were having a egr problem it would blow black smoke.

Is the check engine on?

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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If your OnStar is working, push the blue button and ask for the OBD codes, and write them down. Post them here. If there is something wrong with the fuel injection that is making the car run rich, as it certainly seems like is happening, there will be OBD codes that will tell what the problem is.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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Unfortunately, it is considered normal right now. I've had a 2008 cts and a 2011 cts with the same 3.6 engine, and they both did that. I now have a 2013 buick regal gs 2.0 turbo and it does this as well. All of the forementioned engines are direct injected, so it seems this is common with these engines. It cleans off pretty easily, but comes back wihin a few days.Never had any driveabilty problems. If you are having driveabilty problems, then there is another problem. Hope this helps.

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This perplexes me. Direct injection improves power, economy, and emissions by providing better combustion. If the combustion is better, then now is unburnt *carbon* getting clear through the cat and settling on the tips???

The only thing that I can think of is that when the car is running open loop right after starting, before the cat lights off, it is rich enough to have a light carbon mist *and* the moisture in the exhaust is condensed by the cold exhaust, so that a light film of carbon accumulates inside the tips. If that's all it is, it's cosmetic. If it's worse that that or accumulates during running with the DFI in open loop, then it's bad enough to ruin the CAT well before any current EPS-directed warranty period.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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It is safer for cars to run a bit rich at WOT than lean. It tends to cool the engine and it is safer to avoid detonation under load.

Bruce

2016 Cadillac ATS-V gray/black

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Yeah, that's why it does it when it runs open loop, cold, or when there is a sudden power demand, etc. But the soot will form, it seems to me, only when the exhaust is cold and condenses moisture out of the exhaust gas which catches the carbon.

I would ignore it. You will burn it off if you drive 45 minutes a trip with a warm engine. A lead foot helps, which is probably why I never saw the problem.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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The first few months I had my car, the exhaust tips were VERY clean...

You could hardly tell there was anything on them at all.

After I had it TUNED... they stay a dark blackish gray...

Doesn't matter if in town or on the highway... they stay the same...

Like this picture I just took.

.

20130910_095844_zpsb5cd682e.jpg

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