Black Soot

[Sierra Dan]

26 minutes ago, US Dashworks said:

good ol direct injection. big black puff on startup everytime.

My soot reference wasn't just the puff on startup, but the Soot from a richer running engine.

You can also see it collect on the back of the muffler out the drain hole as well as Tailpipe.

None on mine with E85 

[SS502]

On ‎8‎/‎25‎/‎2018 at 1:21 PM, Sierra Dan said:

ZERO Soot on mine.

Then again I run E-85

Hey Dan...I am assuming you are running the 5.3 FF to be able to run E85? The OP has the 6.2 and doesn't have that option or at least I don't think he does. I am asking because I've read that there is a way to (well on the 2018 Yukon) to add the sensor and somehow reprogram fuel mapping (I don't even pretend to know what that entails) via a tuner. If you have the 6.2 and did all that how much of a pain is it?

[TRKLGND]

On 7/28/2018 at 5:13 AM, Retired Bob said:

My 2014 looks the same way. When it was still under warranty I took it to the dealer and lead mechanic said that was normal. It still bothers me today when I wash the truck and see the muffler. I have tried E65 and I do like the way the truck behaves, esp the transmission.  But locally the only E85 is from a Spinx brand station (not Top Tier) but they do sell E85, pure gas, etc - the price for E85 is only $0.10/gal less than Regular, so the reduced miles per gallon for E85 does not make this a good buy. So I'll live with the sooty muffler.

The OP was talking about the 6.2L.  It is not rated for E85 and without an alcohol sensor and tune it will barely run and throw codes.

[TRKLGND]

On 8/25/2018 at 1:21 PM, Sierra Dan said:

ZERO Soot on mine.

Then again I run E-85

The OP has the 6.2L.  Not E85 compatible. 

[Black02Silverado]

11 minutes ago, paracutin said:

The OP was talking about the 6.2L.  It is not rated for E85 and without an alcohol sensor and tune it will barely run and throw codes.

Funny, our Suburban isn't E85 capable and my 2002 isn't either and they both run just fine on E85.

[TRKLGND]

6 minutes ago, Black02Silverado said:

Funny, our Suburban isn't E85 capable and my 2002 isn't either and they both run just fine on E85.

I'm not willing to risk trying it on my 2018.  
I do see from your signature that your 02 is tuned.  Could that be the reason it doesn't have an issue with E85?  Just asking.  

[Black02Silverado]

2 minutes ago, paracutin said:

I'm not willing to risk trying it on my 2018.  
I do see from your signature that your 02 is tuned.  Could that be the reason it doesn't have an issue with E85?  Just asking.  

Yeah, my 2002 is tuned but not for E85.  It doesn't have the sensor.  I notice better throttle response and a little more power at least it seems that way when I run E85 in it.  As for the tune I run the 93 performance tune on it from BB and so the higher octane of the E85 probably helps.

[L86 All Terrain]

It's the nature of modern Direct injection engines, most do it when you hammer down on the gas. Not sure if it is oil entering the intake because of crankcase pressures, or unburnt fuel. Any pickup I have followed in recent years has done this when they floor it to pass someone, Ram Hemi, Ford Eco and 5.0L and the GM trucks. You can see it puff out pretty good when they mat it, not on diesel levels but as much black smoke as a modern "clean" diesel. 

[Black02Silverado]

48 minutes ago, L86 All Terrain said:

It's the nature of modern Direct injection engines, most do it when you hammer down on the gas. Not sure if it is oil entering the intake because of crankcase pressures, or unburnt fuel. Any pickup I have followed in recent years has done this when they floor it to pass someone, Ram Hemi, Ford Eco and 5.0L and the GM trucks. You can see it puff out pretty good when they mat it, not on diesel levels but as much black smoke as a modern "clean" diesel. 

All vehicles do it when you floor it and it down shifts.  My 2002 does it, and I have seen several cars as well puff out the exhaust when they go to pass the car in front of them or pull out in front of me from an intersection.  Our 2008 Acadia had black tail pipes and it wasn't DI. 

[crushNchowda]

vehicles run pig rich from the factorty.......high power, direct injected, premium octane guzzling vehicles produced by GM are probably THE WORST offenders of this (along w/ pulled timing, low shift torque, high interference of torque mgmt, etc.) - which is also why you have historically seen GM smallblock V8's produce big power gains from tuning alone.

[Black02Silverado]

2 minutes ago, crushNchowda said:

vehicles run pig rich from the factorty.......high power, direct injected, premium octane guzzling vehicles produced by GM are probably THE WORST offenders of this (along w/ pulled timing, low shift torque, high interference of torque mgmt, etc.) - which is also why you have historically seen GM smallblock V8's produce big power gains from tuning alone.

Not necessarily, I've seen a bunch of BMW's where the back of the vehicle was black, not just the tailpipes.  LOL

[crushNchowda]

19 minutes ago, Black02Silverado said:

Not necessarily, I've seen a bunch of BMW's where the back of the vehicle was black, not just the tailpipes.  LOL

well they're typically DI turbos now.....whole other level of running factory rich lol! - also, the NEWEST ones you should see less of that, but was also a big reason for the documented soot build up on valves, which is entirely different situation & much more common vs. the camp arguing for catch cans on N/A DI motors like ours.

[Z45]

Never seen any of my black soot on 3 (12,15 & 17) 6.2L trucks.  I always use (WM) Murphy 91, and rarely Shell,  lowest prices here, no 93 available here.   It could be the brand of gasoline in your locale.

[SS502]

I get it on mine, regularly. I had a local muffler shop (been in business here for over 30 years and is a favorite for the muscle car crowd) install my Borla cat-back. He wanted me to come back after 300 miles so he could re-torque everything after a few good heat cycles. Well I (he lets me in the shop) noticed the soot and asked him about it because my old a$$ immediately thought it was running too rich. He told me that he sees it every single day on the new vehicles be it car or truck, from every manufacturer. Comes off easy if you keep up with it...I check my oil once a week and then use the paper towel to wipe the soot off.

[Glava2876]

It is definitely a GM DI 6.2 normal situation. My 15 Denali, previous 15 Corvette and the 19 Corvette I traded it in on all have the same soot. Like others have said, not too bad if you keep up with it -sort of like brake dust on rims. When I wash my vehicles I do the tailpipes -I have been using Mothers Mag & Aluminum Polish and it comes off very easy.