Help with possible PCV Failure

[Josey12453]

I’m curious if anyone has had any issues with their PCV on the RS3. My current problem is I am getting a misfire on cylinder 5 and noticing just a small amount of smoke coming from the engine bay when the car is first shutoff. As far as cylinder 5, I have swapped plugs and coil packs and the misfire has remained on cylinder 5. The misfire itself only really occurs when restarting the car after coming up to temp and usually happens around idle RPMs. It has never occurred at high RPMs nor does it come in multiple times. Other info about the car is that it is tuned by Unitronic with stage 1+ and stage 2 TCU. I have tried putting the car back to stock and it didn’t make a difference. I’ve attached a short video of my removing the oil cap and the car making a weird noise. It isn’t the high pitched whistle I have heard from other cars having a PCV issue, but it does sound like it is coming from that area of the car. Any help would be greatly appreciated.



https://youtu.be/SQVMrRs4GEY

[Rommies]

I don't think it's very expensive to replace the PCV....but they are known to give issues on the MQB platform.

Funny enough...i have not heard about PCV failures on the 8v2 RS3 (EA855 Evo) engines.

So you might be the first person I hear of!

Sent from my SM-G998B using Tapatalk

[o1turbo30v]

How did you determine your misfires? CEL or through logging, some misfires are common and not to worry about.

Also if your pcv is bad you will certainly get a CEL for system to lean or evap leak along with engine running issues.

[Josey12453]

The misfire is causing the check engine light to come on when it occurs.

[o1turbo30v]

The misfire is causing the check engine light to come on when it occurs.

Could be a fuel injector issue since you’ve already ruled out plugs and coils

[Effchuck]

Are you having any idle issues? Over / underboosting issues? Odd but intermittent throttle related issues during daily driving?

FWIW - I had some of the items noted above, which was identified as my PCV and fresh air tube (cracked) running from the PCV to the turbo. Didn't set any soft or hard codes and wasn't picked up by doing a smoke test or boost leak test.

[Josey12453]

Are you having any idle issues? Over / underboosting issues? Odd but intermittent throttle related issues during daily driving?

FWIW - I had some of the items noted above, which was identified as my PCV and fresh air tube (cracked) running from the PCV to the turbo. Didn't set any soft or hard codes and wasn't picked up by doing a smoke test or boost leak test.

I appreciate the reply. I’ll do some more checking with the vehicle. I haven’t been driving it since this occurred out of an abundance of caution. I did notice that the first time I removed the oil cap and it made that noise, when I put the oil cap back on smoke did come out from that junction between the PCV body and the fresh air tube that goes to the turbo inlet. I’m just trying to be as certain as possible that this is the cause before I start throwing more parts at the car since they aren’t very cheap for a Pcv and related components.

[Josey12453]

Has anyone who has a properly functioning PCV had their car make a noise when they removed their oil cap like the one I linked above?

[Effchuck]

Yes, my car made a strange noise like that from the diaphragm area. Was strange oscillating noise with the oil cap off and then got more intense for a brief moment by shutting the car off