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Our exhaust tips looks pretty dark visually, not quite "black" but not the light "tan" that indicates more complete combustion. Any comments from others?
 

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Our exhaust tips looks pretty dark visually, not quite "black" but not the light "tan" that indicates more complete combustion. Any comments from others?
I noticed this way back when I purchased a 2011, 2.4 Equinox. The inside of the tailpipe was sooty black. I asked the dealer to determine why this was happening; the car had about 1,000 miles at the time. All of my other vehicles had clean tailpipes, no deposits at all.

The dealer checked the fuel trim calibration and a few other things. It was determined at that time that everything was normal, and the black sooty deposits were the result of the new direct injection fuel system.

My port injected vehicles have clean pipes; my vehicles with direct injected engines have black sooty deposits in the pipes.

My point is that what you are seeing is supposedly normal for a direct injected engine.

I remember when I was young, had older carbureted cars, and we had leaded fuel; We could determine how well the fuel system was working and the general condition of the engine by the color of the tailpipe deposits.

If it was snow white inside the pipe, it was running at the optimum calibrations.

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I remember when I was young, had older carbureted cars, and we had leaded fuel; We could determine how well the fuel system was working and the general condition of the engine by the color of the tailpipe deposits.

If it was snow white inside the pipe, it was running at the optimum calibrations.

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Right you are.

I can get my 2014 3.6L Nox to run much cleaner at the tailpipes if I use 91 octane gas.
On another note, my 2018 Encore 1.4L Turbo with Sequential Port Injection runs very clean with 89 octane.
 

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Right you are.

I can get my 2014 3.6L Nox to run much cleaner at the tailpipes if I use 91 octane gas.
On another note, my 2018 Encore 1.4L Turbo with Sequential Port Injection runs very clean with 89 octane.
Yes, when I had my 2004 LS1, GTO with port injection; the pipes were absolutely clean inside, same is true with my 2009, 5.3, Silverado.

All of the direct injected vehicles I own have black soot inside the tailpipes: Three of the four in my signature below.

My thoughts are: How can the O2 sensors remain effective with all of the hydrocarbon deposits that must be accumulating on the sensors as the engine runs. If it's in the pipe, it also must be on the sensors too.

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Our 2018 2.0t is black too, has been that way since new.
My 2019, 2.0 Redline is the same. Black residue collects inside the tailpipe and around the edge of the exhaust outlet tips.

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It cleans off easily when washing vehicle (if you wash by hand). In summer, I only hand wash and every vehicle we have gets the pipes cleaned during wash. All three have the exhaust soot but it's not nearly what occurred on the VW diesels we used to own.
 

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Do you use anything special to clean the black sooty deposits off of the chrome exhaust?
The deposits wash of quite easily with car wash solution, but doing so contaminates the wash mitt or cloth that is being used.

I usually use a paper towel laced with WD-40 or just some water/car wash solution on a paper towel.

Either will remove the deposits, and using a disposable paper towel prevents getting your wash mitt contaminated with soot.

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My 2020 Terrain Denali has the black on the exhaust tips too....I was thinking of maybe an oil catch can....it worked on my C5 Vettes......what does anyone think of this ?
 

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My 2020 Terrain Denali has the black on the exhaust tips too....I was thinking of maybe an oil catch can....it worked on my C5 Vettes......what does anyone think of this ?

I think this is caused by the Direct Injection, and I doubt if the catch can will help. I think that people that have used Tier 1 gasoline have had better success.
 

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when I hand wash, I use a little dish soap in wash bucket. when washing the car, I wash the exhaust tips. Getting the wash mit dirty is what's supposed to happen to the mit. it's not difficult to wash the black soot off.
 

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I have so far only used tier 1 gasoline 93 octane
Same here, although early on I did fill a couple of times with 91 octane (no ethanol)

If it's a direct injected engine, most likely you will experience a buildup of unburned hydrocarbons inside the tailpipe; regardless of the fuel used. :sad:

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That makes no sense to me but.....what do I know....back in the day you wanted white at exhaust tips
When we had carbureted engines and used leaded fuel, an indication that the engine was in good mechanical condition and the ignition and carburetion was tuned properly; the tailpipe deposits would be snow white.

When unleaded fuel was mandated, and fuel injection was the norm, this wasn't so much of an indicator of a healthy running engine. In many cases, there were no deposits at all; it was the lead that was added to the fuel that made up the bulk of the observed deposits in the older cars.

Fast forward to today's vehicles with tiny displacement, turbocharged, direct fuel injected engines; the way the fuel trim is calibrated and the incomplete combustion during cold start/run conditions, we are back to deposits in the tailpipe. Unfortunately now sooty black deposits are what's normal for the current engines.

It's hard to believe these engines can meet emission standards while emitting soot from their exhaust system.

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One interesting thing I've noticed - - -
The 2015 Equinox we had with the 3.6L LFX V6 engine was very sooty. A week or two driving would make the tail pipe ends and insides black.
The 2017 Chevy Colorado and 2019 GMC Acadia we have with the 3.6L LGX/LGZ V6 engines have much . .. . MUCH . .. less soot at the tail pipe ends.

Even after +3 years and +20K miles on the Chevy Colorado, the tail pipe ends get only light soot that I can only see if I don't wipe them off of many months. I think I may have wiped them down only 2 or 3 times a year when doing a good hand wash.

Based on that. . . somehow the newer LGX/LGZ V6 engines run cleaner.
 

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One interesting thing I've noticed - - -
The 2015 Equinox we had with the 3.6L LFX V6 engine was very sooty. A week or two driving would make the tail pipe ends and insides black.
The 2017 Chevy Colorado and 2019 GMC Acadia we have with the 3.6L LGX/LGZ V6 engines have much . .. . MUCH . .. less soot at the tail pipe ends.

Even after +3 years and +20K miles on the Chevy Colorado, the tail pipe ends get only light soot that I can only see if I don't wipe them off of many months. I think I may have wiped them down only 2 or 3 times a year when doing a good hand wash.

Based on that. . . somehow the newer LGX/LGZ V6 engines run cleaner.
You've mentioned this before; I wonder what has changed to make the current engines produce less unburned hydrocarbon deposits.

Is it merely a fuel trim adjustment or maybe some other more significant changes?

Whatever the differences, it would be nice to incorporate these changes into the prior models.

It's a wonder the fuel trim calibrations can be maintained in the engines that produce so much soot; imagine the deposit buildup on the tip of the O2 sensors!

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