Hey guys, I hope you can help me with a problem I'm having.

I recently bought a used 1997/1998 A6 Quattro wagon with the 12 valve AFC engine in it. I've put a lot of time and effort into repairs. New head gaskets, EGR valve. O2 sensors, starter, water pump, timing belt, etc etc.

Anyway, there is one last problem that I can't seem to figure out. When I start the engine I start to get some white smoke out of the exhaust. I think it might be unburned fuel.

Now I know what you are thinking, head gasket leak right? The problem is that it's not consuming a drop of coolant! (I replaced the expansion tank so it's easy to see, and yes, I used the pink G12 coolant)

Anothe clue is that if I drive it around a little it seems to stop. I thought it might be unburned fuel as a result of a leaky fuel injector so I replaced those as well (They needed it after 186k miles)

It seems like it might be something to do with the computer controlling the rich/lean mixture (I only replaced the two O2 sensors in the exhaust manifolds and not the ones after the cat)

Any ideas? could it be the fuel pressure regulator? One of the few parts I did not replace were the Kombi (secondary air injection) valves. Could it be this? I cleaned the EGR passage in the intake manifold well when it was apart (man was it clogged!!)

Any thoughts would be appreciated,

Matt