Figured this title would get all of the degenerates to at least pay attention..
When I start my GTS up in my garage, all sorts of soot or whatever spits out from the pipe and onto my daughters' bike, garage floorand the wall behind.
yes, I know this is normal. BUT. super dirty and annoying.

Three questions:
Why does it do it?
Any way to stop it?
Best way to clean the drywall and daughters' bike? (I've heard from someone to use spray-away)..

Thanks in advance!

 

Don't back in just go in the normal way.

 

Combination of carbon deposits and condensation (mixed) that gets ejected? It sounds like you back your car into its spot in the garage? if so, why don't you park "nose in" and lift the overhead door before you start the engine. Otherwise, a couple of coats of an oil base exterior paint should be more washable than interior paint on drywall. And ... move your daughter's bike out of the way.

 

Be safe; wrap up you tips before up before turning her on

 

Listening

 

Same with mine. I'm quite proud of it. Seems to be a lot more juice if she stays parked longer.

 

Nerd time: Actually, much of that water is a byproduct of combustion. You are combining hydrocarbon-based fuel with oxygen and igniting it.... some of the by-products are water (H2O), carbon monoxide, carbon dioxide, and others. Once the exhaust system and gases are hot enough, that water stays in vapor form and you don't notice it. However, when the exhaust is cooler, the water can condense on the cooler metals on its way out and pick up some carbon deposits in the exhaust, and you get the blackened spitting. All cars do it to varying degrees, its just more noticeable on some. There's no way to stop it other than just shielding things or pointing the exhaust in a more harmless direction as previously recommended. Less idle time before departure helps too, just roll out sooner.

 

Love the comments about not backing the car in...,,

 

I wish I had seen this post sooner, I have way too many kids!

OP- I drive my 911 two, sometimes three times per month at most, and when I turn her on her pipes are extra juicy. It's just mother nature doing her thing, and it's completely normal.

 

By far the best answer

The Fat Kid wins

 

This.

 

I've heard that some people pay good money for stuff like that

 

I have a black metal diamond print piece of aluminum on the wall of my garage for this very reason. I have to back in when I want to put it on my 4 post lift (due to a beam in the ceiling) and I get the exhaust within millimeters of a white wall.