elf_cruiser

So I decided to look under the hood and see just what's going on with this whole carbon deposit build-up issue. I'm starting this thread because I'd like to find a way to prevent it. I have about 5500 miles on my S5, so it's not too late to start preventative measures and protect my valves. I snapped a couple of pics to start off with - let's look at the culprit...

In case you're not familiar with PCV - I circled the PCV hose in blue.
Pic 1 - the attached PCV hose - The engine sucks air from the valve cover to keep a slight vacuum inside the crankcase. The crankcase needs to be ventilated for air temp differences between a cold and running engine.

Pic 2 - close up of said hose...

Pic 3 - valve cover port, see the oil droplet? That's going straight into the intake...

Pic 4 - the throttle body port for the PCV hose, you can see the shiny oil residue there.

Pic 5 - inside of the PCV hose - same shiny oil residue.

elf_cruiser

So , as of this moment, my plan is to set this up like you would a race car (no emissions, etc.) and get one of these PCV filters -


I'll stick this on the valve cover, and cap off the port on the throttle body. Simple. We will see what happens.
I can't believe that there is no valve or filter on this PCV hose, come on Audi???!!!
I also didn't see any sensors, so if the ECU is monitoring crank case vacuum, the sensor must be somewhere else. I'll find out on Saturday if the new setup causes any problems, and report back...

Please let me know if this has been tried before, in case I am wasting my time...

rs4-380

well, you are missing some fairly important things here.

One, the valve cover does not go directly to the TB. The hose from the valve cover goes to an oil separator, which then goes to the TB. Now obviously the functionality of it may not be perfect, but it is much more effective then a hose from the valve cover to the throttle body.

secondly, running an open element filter is asking for trouble. Not only will it most likely make a mess of your engine bay, I also pretty much guarantee it's going to throw codes as well as pulling moisture directly into the engines lubrication system.

Alkivar

agreed...

if you are worried... put in a catch can, but an open filter is begging for problems down the road.

elf_cruiser

Ahhhh - I will check it out this weekend, then. I guess their oil separator is not up to the task? As far as moisture getting into the crankcase - I've never been too concerned on buggy motors, but with something I'll be driving everyday, that's a valid point.

rs4-380

also, an atmospheric vented system (especially one that is not vented through a catch can) will vent vapors into the engine bay and into the car (no matter how good the interior air filtration system is). I doubt that is something people will put up with on a 45+ thousand dollar car.

rs4-380

may not be a problem in arizona as it can be in other parts of the country, but overnight temp swings can cause condensation to form.

IAS5

serious question- how big of a problem is this really? from what i've read, this is not really a common issue.....

are you experiencing issues from this? are you looking for preventative measures that may not even be necessary?

Steve

BlueSander

I do not think what you do would fix the problem. Keep in mind there are a few top rated Gas brands out there that Audi recommended (I know, I was one of those opposing this but after looking used R8s and problem ppl run into, i will follow Audi's recommendation from now on). That should help a bit.

elf_cruiser

IAS5 - you certainly could be right. I am just trying to take preventative measures based on what i've seen around the net. It's entirely possibly that on my 2010 model, Audi has already solved the problem and I have nothing to worry about. But - I am going to find out for myself.

As for the condensation - if you think about it, the possibility exists anyways - cold air can flow through the airbox and stock filter, to the throttle body, and on down into the crankcase. Putting a PCV breather on the valve cover may make it a bit more likely, but I'm not sure that it wouldn't happen anyways... And besides - oil temps in a running engine should be over 250 deg. So any water in the oil would evaporate quickly after you've had the thing running for a bit...

Hey - this is all about learning, and getting the info out there. If there happens to be an easy fix then why not do it?? If not, then I wasted a little time and money - wouldn't be the first time...