Was driving yesterday breaking in my motor when at one stop sign i noticed my idle was about 250-300 higher than usual, TPS was reading 0% and i checked all the usual vacuum leak spots everything was good. Got back to the garage and ended up finding out when i squeezed the PCV hose closed the idle returned to normal, my first thought went straight to worst case scenario, i blew out a gasket or RTV seal in the oil pan or front cover but after checking the check valve is fully operational so no boost went into the oil system. this morning checked the floor under the car no dripping oil, also for context i have an aftermarket oil filler neck and also dont have the OEM PCV valve I'm simply using a one-way check valve that allows vacuum but prevents boost from going the other way, in between a hose that connects the filler neck to the UIM, i also have a stock port engine so it pulls a healthy 19-20 inHg of vacuum at idle. Is it actually a possibility that i SUCKED IN a seal or gasket somewhere from to much vacuum and now i have a vacuum leak from somewhere in the oil system? I've heard of overpressuring the oil system and blowing a seal out but never sucking one in. (also linked a video for reference)

 

this could be it, proper pcv valves don't create vacuum leaks. check this info from radium engineering:
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Very interesting, so to confirm a REAL PCV valve can actually modulate the AMMOUNT of vacuum that is placed on the "crankcase" instead of being full vacuum all the time like a simple check valve. This helps put my mind at ease EXCEPT for the fact that this symptom started randomly and the car was idling fine with the check valve for a few hundred miles of driving, hopefully this is just a coincidence.

 

https://www.tomorrowstechnician.com/...re-pcv-system/

 

Also consider your IAC (Idel Air Control) valve might be sticking. This has happened in several cases recently up here. Fairly easy to remove the IAC valve to check. (Don't drop the little screws!)

Also gasket if NLA, so be gentle with it.

 

My IAC actually isnt plugged in right now so i know for certain its not that haha, im going to be repining my harness to get the IAC to work on my Haltech soon.