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      12-12-2021, 12:56 AM   #18
ctbear
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Drives: 2015 335i m-sport
Join Date: Dec 2018
Location: LA

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Quote:
Originally Posted by audi01 View Post
Sorry for the delay and long post.

Hi, I replaced the sensor and although it gave a stable reading according to ISTA it did not fix the problem. I did another visual inspection of the intake and crankcase ventilation systems and found no visible cracks or leaks and then did a test of the pcv. I connected a pipe to the pcv valve nipple and dipped the end into a small bottle containing some oil. Started the engine at cold and initially did not see any suction of the oil but within 10-20 seconds (after the idle started to come down) the oil was being sucked up the pipe to a height of about 15-20cm and held at that level so I assume that there was some vacuum had been generated at the pcv for a short period of time during that startup process. I re tested after the idle had settled down to normal (650rpm) by disconnecting the pipe, reattaching it and the oil was slowly being sucked to a height of about 5cm so the vacuum had dropped but was still present. I think there is a small leak in the pcv although I still don't understand why it is worse at cold start (fault code 101F01 & 118001) and not during normal operation. There are no oil leaks around the VC so I think it's just the pcv diaphragm which has a small tear.

Can anyone confirm that the PCV should not have any vacuum at the nipple at any time? From what I read online one side of the valve is open to atmosphere so that when a vacuum is created by engine on the other side, the diaphragm closes against the internal spring and closes (or opens)? a valve to divert oil vapour into the turbo inlet pipe. Want to confirm before I go ahead and order an new VC. Thanks.
Have you tried using ISTA to Calculate a TEST plan?

Refer to 8:00 mark in this video:



The TEST plan will evaluate all codes and walk you through it step by step starting with what is most likely to least likely cause of the codes.
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