Cold start, exhaust black crap!

[Hyper_Mike]

Hey,

The title best depicts what I am getting. black crap coming out the exhaust on cold starts. This pic below is 2 starts worth and seems like and awful lot!
I am running a turbo back exhaust with only a 100cell cat and the rear muffler and only started really doing it after i got the exhaust fitted at the start of the year.

Any input would be great! Cheers

 

[BMGTZ]

unleaded petrol leaves a soot residue.

A good cat turns unburned hydrocarbons into carbon dioxide and water.....soot mixes with water= black shit on drive way until the exhaust heats enough to dry out the condensate.

Well at least that is what my pissed brain is remembering.


Just tells me your cat is working and your old one wasnt

 

[Django]

do you get smoke from the exhaust when warm?

 

[evo-gsr]

What the pisshead said is correct.

 

[Hyper_Mike]

do you get smoke from the exhaust when warm?

Nope none whatsoever. Sounds like it's all good

 

[BYBY5L]

Mine does that but I dont have a cat?
I thought my gsr was just obnoxiously rich, guess it must have a cat after all

 

[3VOLUTIONIST]

mine does that (albeit not THAT much) and I've just got straight through piping from the turbo to the outlet, no cat. Assumed it was just carbon

 

[unhuman]

+1 no cat but still does it just not to that extent.

 

[BMGTZ]

Im guessing that no one has a cat converter in their mouth either.... But on a cold day we can see condensation on our breath too for the same reason a car even with out a cat converter will do this in a cold climate. PUT a cat in and it will do it to a much greater extent and for longer.

 

[GeoKez]

My whole shed floor is covered with that shit. Got annoying after a while. I used to wrap a towel loosely over the end of the pipe till it got warm. Not to practicable for a daily thou. Dog got it in its eyes once when it walked round the back of the car, it fucken wasn't happy bout it either.

 

[MDK87]

My understanding is that you have increased the amount of surface area for the water to condense on. Until the complete exhaust system is hot, the water will condense on the cold pipes, mix with the soot and spit out the tailpipe. I believe stock systems combat this by using the final muffler as a 'catcher'. That's why the bottoms of them always rust out, because the water can pool up there.

EDIT: You can visually see this when you take an oxy-acetylene torch to a cold piece of steel.

 

[BYBY5L]

Ah thats why when I had the quiet apexi muffler on it didnt show up really,not that the black spots a concern, just gotta remember to not warm the car up when its backed in the garage