Built motor PCV woes - Input appreciated... Excessive blowby? Vent to atmosphere PCV?

[Quebster]

Sorry guys, I didn't mean to create this thread and then ghost it. Been a busy week, and since the site changeover I don't get notifications on my phone anymore.

What's plugged into the integrated boost tap on the Spulen plate?

I have it plugged, nothing is using that port.

And what TIP are you running? It's not in your build list.

Currently have a BMS TIP.

This is somewhat speculation, but only reasonable explanation was oil was pooling up in the valvecover and blocking the pcv vent basically, then I'd get back on the throttle and the blowby pressure would just push/suck the liquid oil straight out. I overfilled a VTA can at one point and oil started spraying onto the headers, I'm just lucky the car didnt catch on fire.

That's actually pretty interesting, I have a fairly knowledgable buddy that speculates the same, more or less. He keeps saying he thinks it's an oil drain issue to where oil isn't draining from the head fast enough.

 

[Quebster]

Did the 'pull the dip stick out to see if the idle gets rough' and nope, no change. Unscrewed the oil filler cap and it's pushing air out. fml
It's some how adding more pressure to the crank case which is uber no good.

The pressure didn't seem to cause any issues as compression is still good on the car and it runs great, but ugh about the whole situation.

Honestly that test is only good for the OEM PCV. The OEM PCV puts the crankcase at vacuum whereas aftermarket plates do not. It's normal for nothing to happen when you remove the oil dipstick and/or oil cap with one of the PCV replacements on, from my understanding.

EDIT: What he said:

...but it looks like the OEM pcv is a 2 way system that applies a suction on the crankcase at idle/cruise. And the aftermarket plates are simply a metal piece with some baffling that vent out the hose to the air intake. So with aftermarket plate, you'd expect some positive pressure when removing the oil fill cap etc. Also I don't think idle is going to be affected by pulling off the oil cap or dipstick. That is likely only applicable to engines with MAF and pulling in unmetered air in those scenarios.

With OEM PCV you should absolutely get rough idle if you pull out the dipstick and oil cap.

 

[Quebster]

I know most of you will laugh, but Nik from CTS is sending me their PCV plate to try. I've seen several people talk about how it has solved their oil surge issues on track as well. Essentially when I get my turbo back, I'm doing all the health checks (mainly compression), throwing OEM PCV on, and testing/tuning more. When I confirm all is well, I'll experiment with PCVs again.

FWIW my OEM PCV has held up to 40PSI bursts early in the year when we started tuning for the EFR7163 and I had all my wastegate issues. It's survived most of the year holding 32+ psi, including a track night. So it has held up well for me, granted I doubt I've driven the car as much as y'all. My only issue with OEM has been the oil surge stuff at track.

I have the BL, probably going to try the BM too. DBV2 Dan has told me the BL is actually for the 1.8, and the BM is for the 2.0L... I really doubt it makes any difference, but hey.. worth trying and not too expensive.

Other thing I still have on the back burner is possibly running a non-return vented system. Tap the top of the catch can, block off the port that returns to intake. No idea if this will help anything or if oil will just push up through the breather filter, lol.

 

[Quebster]

Is there a baffle in the "doghouse" on top of the Spulen PCV plate? The VWR plate has one that more or less forces the oil to climb over it before it can flow to the CC. It would probably be an improvement to either design to have the hose fitting on top of the doghouse (exiting vertically) rather than in front...

Yeah:

 

[aaronc7]

I thought a little bit more about the rough idle when pulling the oil cap thing on oem pcv. On most speed density cars it would not have such an issue because the air being sucked in would be seen and measured by the MAP sensor. But the pcv layout on this car, the air that sucked back into engine is basically right at the intake valve and I guess it's likely the MAP sensor isn't picking up on it. Don't mean to derail just wanted to close the loop and correct myself on that one! Just my theory anyways.

 

[THEREALVRT]

I know most of you will laugh, but Nik from CTS is sending me their PCV plate to try. I've seen several people talk about how it has solved their oil surge issues on track as well. Essentially when I get my turbo back, I'm doing all the health checks (mainly compression), throwing OEM PCV on, and testing/tuning more. When I confirm all is well, I'll experiment with PCVs again.

FWIW my OEM PCV has held up to 40PSI bursts early in the year when we started tuning for the EFR7163 and I had all my wastegate issues. It's survived most of the year holding 32+ psi, including a track night. So it has held up well for me, granted I doubt I've driven the car as much as y'all. My only issue with OEM has been the oil surge stuff at track.

I have the BL, probably going to try the BM too. DBV2 Dan has told me the BL is actually for the 1.8, and the BM is for the 2.0L... I really doubt it makes any difference, but hey.. worth trying and not too expensive.

Other thing I still have on the back burner is possibly running a non-return vented system. Tap the top of the catch can, block off the port that returns to intake. No idea if this will help anything or if oil will just push up through the breather filter, lol.

can you compare the PCV plates of the cts and spulen when you have them both please!!

AS far as the non vented system, just buy a -10 an cap, but it on the TIP and run the line that goes from the CC to the TIP in your fender well or something like that. see if the car runs different. Just don't cover your tire in oil if alot comes out

 

[Twist1]

I thought the ECU relies on the excess crank case pressure and oil to be used in calculating the air mass, pressure, etc.?

Does bypassing the recycled tract cause issues with driveability?

Both myself and my friends 500+hp s3 need to create a system that simply just vents to atmosphere but we are unsure if that would have effects on car

 

[Quebster]

can you compare the PCV plates of the cts and spulen when you have them both please!!

AS far as the non vented system, just buy a -10 an cap, but it on the TIP and run the line that goes from the CC to the TIP in your fender well or something like that. see if the car runs different. Just don't cover your tire in oil if alot comes out

Sure, I will. And oh yeah, DUH. I'm an idiot. Why am I thinking I need to drill a hole when I can just use the -10AN output of the catchcan. LOL. ?

I thought the ECU relies on the excess crank case pressure and oil to be used in calculating the air mass, pressure, etc.?

Does bypassing the recycled tract cause issues with driveability?

Both myself and my friends 500+hp s3 need to create a system that simply just vents to atmosphere but we are unsure if that would have effects on car

 

[donefor]

Cool, thanks for the pics. The design with the bolts coming in from the bottom makes me nervous ☠

Oh yeah there was some explanation of the stock PCV and oil separator here: https://www.golfmk7.com/forums/index.php?threads/smoke-factory-at-the-track.365799/

 

[jimlloyd40]

I thought the ECU relies on the excess crank case pressure and oil to be used in calculating the air mass, pressure, etc.?

Does bypassing the recycled tract cause issues with driveability?

Both myself and my friends 500+hp s3 need to create a system that simply just vents to atmosphere but we are unsure if that would have effects on car

If you are asking if the recycled tract causes issues with drivability with regards to a system like the Spulen the answer is no. If it vented to atmosphere wouldn't the blow by mist being spraying all over the engine compartment? If what I said doesn't relate to what you were asking then I don't understand what you meant obviously. ?

 

[aaronc7]

All the aftermarket pcv plates basically turn the pcv system into a more simple vented setup and abandons modern "2-way" pcv system operation. It's just whether you vent back to the intake/pre-turbo, or to atmosphere. Since these cars are speed density or MAP based, any vented pcv fumes won't affect fueling calcs or fuel trims. It's a factor on a MAF equipped car that keeps a factory vacuum assisted 2 way setup. I prefer to route pcv back into the intake/engine vs VTA. Yeah it's possible to get oil back into the intake tract, but with a properly vented/baffled system it's minimal and if you have a shit ton... it probably means your engine is hurt. Venting to atmosphere is simple and sometimes the way to go if routing back to intake just isn't possible or feasible. But you will probably get some oily mist in the engine bay and it will smell through the air vents. Everyone's tolerance of smells etc is different. On my cammed C5Z I don't mind the catless smell but blowby fumes under the hood/thru the air vents I did not like at all.

 

[Quebster]

I prefer to route pcv back into the intake/engine vs VTA. Yeah it's possible to get oil back into the intake tract, but with a properly vented/baffled system it's minimal and if you have a shit ton... it probably means your engine is hurt.

Any idea how it’s hurt if it is? Less than 10k on the motor build. By hurt you mean what, like excessive blowby? In which case I should have crappy compression and leak down tests?

 

[Diggs24]

Hurt= bad rings
Only thing I can think of on a built motor.

 

[jimlloyd40]

Any idea how it’s hurt if it is? Less than 10k on the motor build. By hurt you mean what, like excessive blowby? In which case I should have crappy compression and leak down tests?

Do you have good compression and leak down?

 

[aaronc7]

Built motors tend to have more blowby in my experience to just being looser.... wider piston gaps for example. When I added a built motor to my other car, I had all sorts of blowby issues. I think over time it broke in more and went down, but I also went overboard and added more vents to the valve covers. I went as far as using a pressure gauge on the dipstick tube to measure pressure and see what was up. In my particular case I had a lot of blowby past 4k rpm, even if low load. Googling it sounded a lot like 'ring flutter' but I wasn't interested in pulling the motor again any time soon and just rode it out and upgraded the ventilation as already mentioned. Hasn't been an issue since so I'm happy.

If you've got several thousand miles on it, it's probably safe to say it's as broken in as it's going to get. Leakdown test and comp test would be the best place to start like you already mentioned!