black soot out of exhaust

[45ACP]

Originally Posted By: chevyboy14
Mines not real watery its more dry black [censored].


Hmmmm. I wish i had a video or picture of when mine did.

Does it shoot out like a mist or like little droplets coughing, getting spit out by the exhaust gas and makes little black spots on the ground? And it sits on the ground like black water? Or is yours like a powder? It used to leak out in a half-liquid form, and it was black.. a black, inky goo that had the consistency of water and felt somewhat hot.

 

[Dakota1820]

When you would give it gas it would spray your hand with black spots . It wast watery though it was kinda like when you get your hands dirty and wipe them off on your jeans or something and it would have that dirty film on them. But doing it and letting it go on the ground made a black stain as big as my hand Atleast. I guess from doing a piston soak. That's only thing i can think of.

 

[45ACP]

Originally Posted By: chevyboy14
When you would give it gas it would spray your hand with black spots . It wast watery though it was kinda like when you get your hands dirty and wipe them off on your jeans or something and it would have that dirty film on them. But doing it and letting it go on the ground made a black stain as big as my hand Atleast. I guess from doing a piston soak. That's only thing i can think of.


That might be it. Carbon being blown out.

Did you take her on the highway and do WOT open accelerations from 30MPH to 60MPH or 70MPH and get the car good and HOT like an hour run? Mine had smoke coming from its exhaust when i did that too. I beleive it created a blockage and was temporarily causing smoke to come out the pipe under the driver seat untl it got blown out. I seafoamed a car a second time, and possibly a third. Didnt piston soak it, however. That was next on my list.

That black liquid is weird, it was like a spatter if you put your hand by the exhaust. Like a blown head gasket would look, minus the smoke and the liquid was black, otherwise the same. I forget if it went away, this long time ago on a K5 or K15.

 

[Dakota1820]

Yea I drove it for about 50 miles. Seems to have settled down. But It was dark so it was harder to see.

 

[Mark_Walk]

My Chevy Trailblazer (132,000 miles) was doing the same thing and getting bad gas mileage. My thought was, the O2 sensor had never been changed and was giving a bad reading causing the computer to run really rich. So, this weekend I put in a new O2 sensor and it fixed it. No more soot and the MPG's went up by 4.

Every time I would start it a blast of black [censored] would shoot out the tailpipe making a big spot of black sooty [censored]. Immediately fixed it after the O2 sensor change.

MPG went from 13.6 to over 17.

 

[ltslimjim]

^Interesting experience. Could it be the 02 was weak and not adjusting the fuel-trims right, causing a rich condition to the point of build-up?

 

[ltslimjim]

chevyboy14, I'd perhaps recommend one more top-end cleaning. Try out Amsoil's Power Foam. It's a huge 18 ounce can! I love it because you can get carpel tunnel by the time it's all over, just a preference for me. :grink:

Seriously, though, I suppose GM's top-end product, AC Delco or Mopar "CCC"(Combustion Chamber Cleaner) would still do the trick. Perhaps wait until your next actual oil change.

Maybe 1 more piston soak(how many have you done now?), and you should be good to go. Stick with good maintenance practice on top of the other things you had laid out in the other thread already.

I mean: Piston soak, top-end foam spray soaking, Kreen/MMO/SeaFoam to crankcase used as directed etc etc...high quility syn and a high-efficiency oil filter is the only other thing to do, really.

Also, have you done anything to treat the fuel system? Red Line SI-1 or Amsoil Pi, etc? Lastly, any serviceable fuel filter?

 

[Virtuoso]

My SL1 did the same thing - it got worse the more oil it burned.

 

[Mark_Walk]

Originally Posted By: ltslimjim
^Interesting experience. Could it be the 02 was weak and not adjusting the fuel-trims right, causing a rich condition to the point of build-up?


I've heard that old O2 sensors get "lazy" and just slowly begin to fail. As you say, I think it was giving a false oxygen reading causing the engine to run really rich to the point of too much fuel build up. This tar like junk would shoot out the tail pipe on start up. Also, the tail pipe is very sooty looking. Didn't look like that in the past.

 

[mechtech2]

Could simply be water that is flushing out crud.
Water is a combustion by product that turns liquid in the exhaust until it heats up.
Some cars are much worse than others regarding this harmless trait.

 

[CBR.worm]

My brothers last Trans Am had dual exhausts that pointed straight back. He would back into the garage. There are still dark circles and black spray/drip marks on the wall from that car. He bought it with 26K on it and sold it around 70K. The engine never gave him a problem, although he could not keep a drivers side t-top on it to save his life.

 

[SteveSRT8]

Most cars do this. Pig rich tuning to light the cats when cold causes a bit of black soot. The water naturally produced will then carry it out.

You should see it drip from the muffler weep hole on our vans with 4 cats!

 

[rslifkin]

^ Yup. Most cars are tuned to run very rich when cold. Since the mods and tuning, the Jeep doesn't run nearly as rich at cold start as it did stock, so it definitely smells for longer after a cold start (cat doesn't light off as fast).

 

[Vikas]

Is there a black oily soot inside the tail pipe? Take a napkin and wipe it out. Don't burn your fingers!

 

[another Todd]

O2 sensors bad. Your tail pipe should look like bare metal on the inside. Black and sooty, sometimes wraping around the outside of the tailpipe about 1/8th inch or so, indicates a bad o2 sensor. When my vehicles exhibit that, I replace the o2 sensor and after a few weeks all the black is gone again and just bare metal is visable. Increased gas mileage is an added bonus of replacing the o2 sensor.

 

[Mark_Walk]

exact situation i had with my trailblazer. soot wrapped around tailpipe about 1/8".

 

[Vikas]

So, yesterday afternoon I took a stroll through our company's parking lot. It is a high tech mega corporation and we have lots of cars. I was hard pressed to find a single vehicle with black soot on the tail pipe or on the bumper. Some Toyota tail pipes were blacker than the others.

If your tailpipe has black soot, you should have the CEL on with O2 sensor code. You are running too rich.

- Vikas

 

[hattaresguy]

If you have soot on the tail of a modern car you are running extremely rich, I'd be shocked if your cat's are not fried or [censored] near.

 

[SteveSRT8]

Soot in the tailpipe-yes. On the bumper-no.

In any modern car there is a short period of time at startup where the mixture is extremely rich and the cats are dead cold. Usually this is just seconds, but it is enough to give the deposits.

Then, at wide open most cars dump fuel like crazy, many times running all the way down to 10 to 1 air/fuel ratio. No cat can process all that fuel, thus a bit more soot.

Anyone ever hear of cat protection mode? That's yet another scenario where excess fuel can soot up your tailpipe.

In short, a little black inside the pipe can be perfectly normal. If you have a black bumper that's a bad thing.

 

[MONKEYMAN]

My 99 SL2 has a black ring on end of tailpipe. Replaced O2 sensor recently. That did not change it. About every S-Series Saturn has that ring on tailpipe. It is normal for that car. Only time I notice carbon is when I floor the car getting up to highway speed.

Now when I see a Ford Focus or some cars with a Mazda engine it will look rusty inside tailpipe. I see no carbon at all.