Black smoke staining bumper

[T_E]

Appears to be a rich mixture issue...and it happens with non-ethanol gas, too.

Just some extra work to clean it up....I have applied several coats of was around the exhaust tips of the Equus and this comes off with either glass cleaner, Honda Spray, or Griot's fast wipe wax.

I have this issue on a Honda Rune, too. Exhaust deposits all over the exhaust and rear drive housing. Lots of extra cleaning required.

My LS series Lexuses didn't have this issue but they exhausted under the bumper....

 

[1FstYota]

It all boils down to function and looks, personally I like how the exhuast looks. I know from the get go that the bumper will stain eventually. It's the same as my cutout on my supra the whole rear end would be covered in soot and where the factory exhaust tip is you can see the bumper turning brown (white car as well).

Running rich is probably GDI and how it's tuned, thinking about it 333hp from a high compression v6 that you can run normal gas in, that's unheard of 5 to 10 years ago, so the richer mixture is probably to prevent the engine from pings and knocks when people don't want to pay for premium in the car.

So it's only a problem when people make it a problem.

 

[Retry]

Has anyone confirmed that premium fuel creates soot? I've not tried any but just wonder if the slower burning properties of premium would have any effect on the knock sensor which might in turn have a corresponding effect on varying the timing which in turn might result in a cleaner combustion. Say what? Now I've confused my own self.

 

[PSL]

Fair question I think about premium fuel creating more soot? I don't know the answer, but I'm sure someone on this forum does. I'm confused abut the second part of your question too.

 

[Gunkk]

Has anyone confirmed that premium fuel creates soot? I've not tried any but just wonder if the slower burning properties of premium would have any effect on the knock sensor which might in turn have a corresponding effect on varying the timing which in turn might result in a cleaner combustion. Say what? Now I've confused my own self.

I steered my friend away from the 5.0 when he bought his WHITE 2012 for just this reason.

I recently plugged in a cheap OBDII sender, and it outputs advance timing to my phone via the Torque app. The spark timing in my 4.6 varies all over the place dynamically with throttle position, engine speed, etc. every second or so on the app (likely much faster inside the engine). I saw numbers from +3.5 to -40 degrees or so with limited testing (dangerous to drive solo and watch the app closely!). Bugs in this code are probably why we get the shake-rattle-roll starts occasionally. I'm sure the spark timing in the GDI's is even more challenging to program than the original Tau.

So based on this, I would surmise that yes are you going to have some GDI soot no matter your driving style, fuel quality, and conditions.

 

[1FstYota]

I steered my friend away from the 5.0 when he bought his WHITE 2012 for just this reason.

I recently plugged in a cheap OBDII sender, and it outputs advance timing to my phone via the Torque app. The spark timing in my 4.6 varies all over the place dynamically with throttle position, engine speed, etc. every second or so on the app (likely much faster inside the engine). I saw numbers from +3.5 to -40 degrees or so with limited testing (dangerous to drive solo and watch the app closely!). Bugs in this code are probably why we get the shake-rattle-roll starts occasionally. I'm sure the spark timing in the GDI's is even more challenging to program than the original Tau.

So based on this, I would surmise that yes are you going to have some GDI soot no matter your driving style, fuel quality, and conditions.

I think your seeing the activity also depends on closed loop or open loop tuning. I'm sure the o2 sensor is making adjustments constantly.

It's just nature of the fuel we run it will get soot, I run e85 in the other car a lot less but still present.

 

[gkbatc]

My white 2013 Genesis' exhaust also leaves black and brown stains on the exhaust tips and bumper. Every dealer seems to have a different excuse why this happens. The simple fact is that if an engine is properly tuned, it will not leave black residue. Black residue means that the fuel is not being burnt cleanly. In other words, there is a problem with the fuel/oxygen mix or the catalytic converter is not working properly. Has anyone had their exhaust emissions checked? Thanks! gkbatc

 

[PMCErnie]

My white 2013 Genesis' exhaust also leaves black and brown stains on the exhaust tips and bumper. Every dealer seems to have a different excuse why this happens. The simple fact is that if an engine is properly tuned, it will not leave black residue. Black residue means that the fuel is not being burnt cleanly. In other words, there is a problem with the fuel/oxygen mix or the catalytic converter is not working properly. Has anyone had their exhaust emissions checked? Thanks! gkbatc

You have a lot to learn.

 

[sluggo]

Based on the reading I've done while on the throne, this is not a gasoline problem. The soot is from oil droplets from the crankcase that get recirculated to the air intake stream via PCV. When the oil droplets hit the back of the intake valve, they bake and leave solids that later get sucked into the combustion chamber and then blown out the exhaust.

This process does not happen in port-injected engines (even though they also have PCV systems) because port injection "rinses" the oil off the back of the intake valve and then combusts the oil in the cylinder, producing few solids.

So I don't think you're going to fix this problem by changing gasoline. Maybe some oil brands produce less soot. Might be interesting to test.

 

[NSXNEXT]

Based on the reading I've done while on the throne, this is not a gasoline problem. The soot is from oil droplets from the crankcase that get recirculated to the air intake stream via the EGR valve. When the oil droplets hit the back of the intake valve, they bake and leave solids that later get sucked into the combustion chamber and then blown out the exhaust.

This process does not happen in port-injected engines (even though they also have EGR systems) because port injection "rinses" the oil off the back of the intake valve and then combusts the oil in the cylinder, producing few solids.

So I don't think you're going to fix this problem by changing gasoline. Maybe some oil brands produce less soot. Might be interesting to test.

Nice write up. Curious who has installed an oil separator or catch can and the results.

I know jnc was looking into having one built for us.

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[Chris5.0rspec]

I got a 2013 genesis rspec 5.0 and I had the back stain also until I changed my exhausted. Now it's gone. It's because all the car run the fuel and air mix very rich and that is what causes it.

 

[PMCErnie]

I got a 2013 genesis rspec 5.0 and I had the back stain also until I changed my exhausted. Now it's gone. It's because all the car run the fuel and air mix very rich and that is what causes it.

You changed your exhausted?

 

[Chris5.0rspec]

I did a muffler silencer delete and left my stock muffler on the car.

 

[Bill K]

I have to clean my exhaust tips every 3 weeks, but have no problem with the bumper.
.

 

[SH66]

Since we are on this topic. How do you clean the exhaust and bumper. Please be specific as what cleaning technique you use, products, and how much time you spend on getting it looking new. Thanks

 

[Bill K]

Since we are on this topic. How do you clean the exhaust and bumper. Please be specific as what cleaning technique you use, products, and how much time you spend on getting it looking new. Thanks

I have yet to have to clean my bumper, but I use an old nylon pot scrubber to clean the tips. The black comes off easy with little pressure. Not sure if I would use the scrubber on paint. You might try a product called "Magic Eraser".
.
If you let the carbon bake on the tips for a long time, you may have to use harsher cleaners.
.

 

[amartz]

I have found that the windshield washer sqeegee at most gas stations works resonably well. Just be sure to rinse it off well in the bucket when finished.

 

[Batwingz]

Just bought a 2012 Genesis, 3.8 premium in white. I am having the same issue. My wife's car is a 2007 Acura TL in white. Her car has NEVER had any black, even inside the tips. There is no comparison and I am totally rethinking my position on this car. Look at the maintenance schedule calling for a periodic Injection cleaner recommendation (not necessary if top tier fuel used) They know they have an issue.

 

[scottdk]

Just bought a 2012 Genesis, 3.8 premium in white. I am having the same issue. My wife's car is a 2007 Acura TL in white. Her car has NEVER had any black, even inside the tips. There is no comparison and I am totally rethinking my position on this car. Look at the maintenance schedule calling for a periodic Injection cleaner recommendation (not necessary if top tier fuel used) They know they have an issue.

You're not understanding the issue. Your 2007 Acura TL does not have a direct injection engine like your Genesis. Please read the thread again because this is the cause, or spend a few minutes with Google. You will find enough info to make your head spin. Audi, BMW, and others' with GDI engines all have this trait. It's not specific to Hyundai.

 

[Chris5.0rspec]

I have posted how to fix this problem. All you have to do is cut out the exhaust salancer in the middle of the car. That's what holds all the carbon. I did this to my 5.0 rspec and never had a problem. The factory settings on the car to run rich. You will also get a better tone out of the exhaust.