Failed MD emissions twice due to HC, NEED HELP

[ThikStik]

I believe that black liquidy crud is from additives that are in lead free gasoline to give it octane. All cars , hot rod or not ive seen have it.

 

[ez at nova]

So in most passenger vehicles, it gets burned or trapped in the exhaust somewhere? And since my GN's system is relatively high flowing (big pipes, no cat, etc), it spills out like a kid with the flu?

 

[ThikStik]

Maybe on a cooler exhaust system it can become liquified and carried out. Whereas it is vaporized on a hotter temp exhaust.
My 71 gto leaves pure black blots all over my garage door, and above its valance panel.

 

[ez at nova]

That's true. 90% of it is when I start the car, or if I stab the gas after just starting it. If I let it sit a few minutes, it cuts way back on the black stuff. I have a feeling it could be more than just a byproduct of gas though, since my pipes would shoot some residue no matter how hot the car got, before I did all the cleaning/tuneup stuff I listed above. Now it seems to only do it when it is first started.