what is the most common PVC failure on 30v 2.8
 

I have a 98 A6 2.8 30v. valve covers and cam tensioner seals are dry, but I get a pretty bad oil smell inside the car but only when I stop at a stop light after a few miles of 55-60mph driving. in town driving I get no smell. I know I have one bad leak from the crank seal or oil pump housing, but that is below any heat source to cause smell inside the car. I have never done anything with the PVC system and I am really totally unfamiliar with it, I don't have vac leaks but where does it clog and what do I need to look for? How to test it?

thanks

Did you check your head plugs? They are behind the cylinder head and like to leak. And when they leak, oil will drip on exhaust pipe causing it to burn. This will produce a smoke that will enter the cabin and smell like burning oil or rubber. It will only begin to appear after the engine is hot. When the car is running smoke may dissipate and maybe this is why you feel it only when you stop.
Pass you finger behind cylinder head and see if there is oil.
The plug looks like this:

http://www.ecstuning.com/Audi-C5_A6-...tml?imgID=7873

A clogged system may lead to this leak. Not only the PCV but suction pump also. It is a good idea to clean it all before things get bad.

I have checked them, no leaks anyplace around the valve cover or tensioner seals.
but I have heard of the PVC causing leaks or getting plugged, visually my hoses look good and I believe they may have been replaced at some point but wanted to see what I need to check on for the PVC system. is it only the 2 hoses, one I think goes from valve cover to valve cover (rear of drivers valve cover and not sure where it goes from their) and one up front on Pass side, not sure where it goes, but I had to unplug one end to do the T-Belt.

Oil vapor runs inside those hoses. The other end goes to the throttle body and suction pump.

so basically if I can blow thru them they are ok? probably only need to remove one end and blow? no valves to worry about?

From head to head up to the PCV yes, but further than this you have valves.
Be careful: if they are old will crack like egg shell. The full hose system including the PCV is sold as one part only.