Exhaust 'spray' on start up.

[johnvw]

Greetings All,
I have just received my 2010 A4B8 2.0LT Quattro ( still in love), 1060 Klms on the clock.
Any idea what the ' black soot like substance with water, possible condensate', from the exhaust might be ??.
Each time I start the car I seem to leave this 'spray' of substance on the driveway.
Persistent hosing will remove the substance, but I would like to know just what it may be.
Best Regards and thank you in advance.
John

[johnvw]

See what happens the the boss pressures you to send an email.

The car is petrol not diesel.

[sunil1234]

might just be old crap sitting in the exhaust from when the car was sitting around prior to being owned by you.

I think you need to drive it hard and give it a good spanking, do you do only short journeys?

thanks

[Crasher]

Carbon combustion residue mixed with water vapour condensate from the fuel and the air.

[XM640]

Hi Johnvw,

I can only guess as for an answer but just so you know ...

My B8 2.0TFSI does exactly what you have described, and even after 30,000km it continues to leave a wet sooty streak on the garage floor. The majority of my use is for long trips so it isn't due to 'short trip' water condensation/carbon build up.

I do note that on cold start up, for about 30 sec, the engine idles very fast which I understand pre-heats the exhaust catalytic converter. My guess is that this is a very rich fuel mixture which creates the excess spray out the back.