E90Post
 


The Tire Rack
 
BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > NA Engine (non-turbo) / Drivetrain / Exhaust Modifications > PCV Valve failure symptoms



Reply
 
Thread Tools Search this Thread
      08-08-2018, 10:57 AM   #1
alexwhittemore
Lieutenant Colonel
109
Rep
1,951
Posts

Drives: 2009 Crimson 328i
Join Date: Oct 2012
Location: Los Angeles

iTrader: (0)

I'm chasing down power loss between 1.5k and 3k that throws no codes and seems to be worse when the engine's warm.

I've been educating myself about the PCV Valve thinking maybe that's to blame, and I came across this video, which suggests a symptom of a failed PCV valve is vacuum in the crank case/valve cover at idle - the PCV valve is failed open, letting the intake pull vacuum on the crank case when it shouldn't.



Sure enough, when I go out and pull the oil cap at idle, I hear a solid hiss as the pressure equalizes.

My question is, is that normal? Is vacuum in the crank case just stronger when the valve has failed, or is any noticeable vacuum a solid indication of a failed PCV valve?

EDIT: N51, FYI.

EDIT: Oh also - no engine codes, per se (lean, persistent misfire, etc). I did get one misfire, once, under load while the issue was acting up. And I do have a code for the secondary air injection system, which can be caused by a bad exhaust mix since the pre-cat O2 sensor is how the secondary air system verifies functionality.
Appreciate 0
      08-09-2018, 05:21 PM   #2
nsjames
Brigadier General
2440
Rep
4,333
Posts

Drives: 08 328xi Touring
Join Date: May 2017
Location: ohio

iTrader: (0)

normal for slight vacuum.

not normal if you pop the cap and the idle changes, or it starts sucching massive amounts of air through the oil cap.
Appreciate 0
      08-09-2018, 05:44 PM   #3
alexwhittemore
Lieutenant Colonel
109
Rep
1,951
Posts

Drives: 2009 Crimson 328i
Join Date: Oct 2012
Location: Los Angeles

iTrader: (0)

Quote:
Originally Posted by nsjames View Post
normal for slight vacuum.

not normal if you pop the cap and the idle changes, or it starts sucching massive amounts of air through the oil cap.
Damn - yea, I don't think either is happening.
__________________
Appreciate 0
Reply

Bookmarks

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -5. The time now is 09:56 AM.




e90post
Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
1Addicts.com, BIMMERPOST.com, E90Post.com, F30Post.com, M3Post.com, ZPost.com, 5Post.com, 6Post.com, 7Post.com, XBimmers.com logo and trademark are properties of BIMMERPOST