The FVC thread.

A6 All/ S6 All
#1

FVC, it’s just an anagram for free venting crank.

Moving on!
So in a thread by vtgt here: http://audirevolution.net/forum/index.php?topic=4939.0.
I wrote that I cured my misfires, rough idle and so on, by deleting my PCV system.
User justincredible told me to be careful, and I totally agrees, but I seen multiple other people doing this over the years and with great results.
I’ve even done it on our old A3, an 2010 2.0 TDI with 140hp tuned to 200hp with DPF and EGR delete.
It did 160.000km with no issues, other than a hefty oder from the FVC system. New owner also runs with the system, I know this because he is my neighbor.

So in the previous mention thread, justincredible told me to test:

So! Here I am, the FVC guinea pig.
If all goes wrong, spare engines in Germany isn’t super expensive and a drive across the border is short and fun -at least on the Autobahn 8)

So, last monday me, my girlfriend and our to kids drove to italy and back.
A total of >3000km (1860miles) was covered, no issues at all and the car just went away … at least on the autobahn which is fun … in a V10 ::slight_smile:

So now the log begins!
One of the concerns is increased oil use, so I’m now testing that. Anything else you guys want me to test, just tell me and I’ll do my best!

Oil level is at max and the odo is at 192.750km

https://d2aztkdj0ezvrk.cloudfront.net/items/1t41153q1Y3u1Y123B2x/Skærmbillede%202019-07-16%20kl.%2021.04.24.png

#2

You’ve got to appreciate a man who steps up when called upon. I’m interested to see your results, and man I’m jealous. Unfortunately, there’s no Autobahn’s here… just aggressive speeding on HOPEFULLY empty highways ;D

#3

Kimovitzh thanks for this thread. Having other options on this monster of a motor is a good thing. There are so many ways these cars can get misfires all we can do to cut the carbon and misfires issues the better.

If you can. Please do what you can to show how you have the system set up. Great work keep us posted.

#4

I’ll keep you guys posted!
It’s worth mentioning that I’ve carbon cleaned the intake and gutted the internals of the manifold.
Other that that the car is stock.

Oh, yes. The autobahn is amazing to drive on, there weren’t many fast cars this time. But I did manage to outrun a Porsche macan turbo and a BMW M2 from ≈100 - 200km/h in this old car with four passengers, luggage and tree cases of sodapops :joy:.

Funny thing though, dosen’t seem to be limited to 250km/h🙈

Right now the venting is done from a 22mm radiator hose on each side down to the under tray, on one side the it vents though the AC hole in this under tray. And on the other side I made a matching hole.
I’ve got som stainless pipe and a bender and will make most of this with a hard pipe to avoid any bends with the hose.

#5

So I’m at 194.422km and since first post I’ve done 1.672km or 1.039miles.
No change in engine behavior, but since last time I’ve looked out for the oil smell and it’s noticeable with the windows down when having a long wait at the red light. Doesn’t bother me that much, but coming from a diesel - no wonder! Oil fog on those are really smelly!
No change in engine behavior.

Oil stick is at just under max, and looks a lot like the picture in first post.

+1.672km photo:

https://dzwonsemrish7.cloudfront.net/items/1f0A323X2M0S0I1N0O1I/Skærmbillede%202019-08-05%20kl.%2020.37.43.png

I actually expected a noticeable usage.
Both measurements were done at the same parking space and the ground is level.

I haven’t had the chance to make the stainless pipe so still no pictures of the set up.

#6

Update time!

So everything is still fine, oil usage is low and at respectable levels.
Only oil related problem was a bad oil pressure sensor, the plastic on it somehow got bad and threw oil all over the front of the engine.
Lost about ~4L of oil on that occasion :grimacing:

Lately I’ve thought of putting an oil-air separator in the mix.
With this the two lines will be joined, the line will be filtered and I can, to some extent, supervise the oil escaping the system.

#7

Great update and this is a good amount of time to look at the range on this. The fact that it’s consuming oil proves its still pulling vac. It would be interesting to see what the bac diff is.

What are your fuel trims at. Can you measure them and report back… thanks for checking back in

#8

I’m guessing that it’s the short time fuel trim and the long time fuel trim?

When I looked ad it, it wasn’t a steady number, seemed to go up and down all the time.

B1 S: 0
B1 L: -3.9
B2 S: -2.3
B2 L: 1.6
B3 S: 3.1
B3 L: -1.6
B4 S: 0
B4 L: -5.5

So, what does the numbers show and are there at specific way to log them, like only ignition on, or at speed or …?

#9

Long term fuel trim should be a number that isn’t moving. Generally you can check it after a drive to see where it comes in at. Chances are if you had numbers that were not steady that is short term trim.

#10

Late to the thread. The first link above is no longer working. Excuse my ignorance but what is the objective of a FVC? Is this to eliminate the PCV system and what would be the benefits of doing so? Would love to see pics and explanation of benefits to this.

#11

Well, coming from a common rail diesel, EGR + PCV was a bad combo.
I removed both and over the +100.000km after that, less issues arrived.

When I removed my IM to gut it, a shit load of oil came out, and oil was found all the way to my valves. Giving the car some pedal on the highway was a cloudy mess.

Instead of replacing the defective PCV I just completely removed it.
Now 11 months and +25000km later, I see less oil consumption.
Removed the IM the other day to clean my injectors and the inside of the IM was bone dry.

#12

I’ve got a VCDS cable now, what and how should I measure the fuel trim?
With engine off after a long drive or huh?

#13

LTFT are long term fuel trims. You would want to gather that from each bank.

The LTFT Data will be shown at idle and then at part throttle values. So you don’t need to log it’s simply just the range percentage wise.

#14

So, it’s been a year and I’ve been driving a lot.

Bought the car with 184.xxx km and is at 216.xxx km.
The PCV delete has been in place at >28.000km.

A couple of months ago I removed the IM to remove the lower part of the internals of the IM to have more air ready in the intake chamber (so far it seems to have a small benefit, but I have nothing more that a butt feel atm), what I noted was a bone dry intake and only a small amount of carbon on the valves.
But with nothin to compare against is just a hunch that is has worked.

Oil consumption was very low until a couple of months ago after a regular service interval, just to get the stamp in the book.
I need to check the underside again to see if it’s a leak or that they used the wrong oil.
What I could gather is that wrong oil could increase oil consumption do to viscosity.

However, I’m afraid that it’s a leak.
Will look in to that later this week.

I’ll see if I can remember to note them tomorrow.
I guess - look at idle with a hot engine?

#15

Oil consumption is kinda normal on these aluminum cars. What’s your consumption rate per 1000 miles?

The fuel trim data is usually good after a short drive as long as you didn’t clear or reset your ECU.

#16

So from what I could gather i should look for block 32

After my drive from home to work this is the values presented in block 32

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