So I started diagnosing the issue from that.
#Volkswagen 2.0t sucking air dip stick code#
I didn't have any check engine light but on one of those cold mornings, I had a fault code detected with OBDELEVEN =P0171 SYSTEM TO LEAN. RPM was normal, but when trying to rev up a little bit the rpm would go up and down (i have a video if that would help). the rough idle disappeared after the temp gauge started to move a bit and that's it , Two weeks ago I started having rough idle only on cold morning start ups. I have an Audi 2008 A3 2.0T with 107,000 km on the clock. Unit.I'm a little bit confused about an issue I was having, Valve N548 is activated by a PWM signal ↗ from the engine control The vent line when the engine is idling if the oxygen sensor detectsĪn excessively high hydrocarbon concentration from the positiveĬrankcase ventilation system. Idling performance is improvedīy the crankcase ventilation shut-off valve N548. To reduce noise, a plastic coil was integrated into the pipe system.Ī high hydrocarbon concentration in the crankcase could impair The clean air then flows into theĬrankcase through a line connection on the fine oil separator.ĭuring the development of the system the following objectives To purge the crankcase, air is extracted from the clean air line
Manifold and thus engine oil being drawn in via theĬrankcase breather or seals being damaged. It prevents the same vacuum forming as in the intake Gases in the crankcase and feeding it back to theĪ pressure control valve limits the intake manifold It has the task of separating oil from the blow-by The cyclonic oil separator is in the cylinder headĬover. The blow-by gases in the crankcase are drawn in byĪnd then fed back into the intake manifold. The crankcase breather systemĬonsists of vent ducts in the cylinder block andĬylinder head, the cyclonic oil separator and the (blow-by gases) reaching the outside atmosphereįrom the crankcase. It prevents vapours enriched with hydrocarbons
I have read of some people making a vacuum gauge that is connected to the oil cap and which can then accurately measure the vacuum. Perhaps it is this part of the system not working properly and as such is not reducing vacuum as much as it should? At the moment we know there is vacuum but don't know how much?Īn objective test would be to measure the vacuum to see whether it is in line with the design spec. The extract notes that the system is designed to reduce the vacuum from 700mbar to approx. Reading the feedback it seems as if a vacuum pressure of some sorts is not abnormal.īelow is an extract from the dealer as to how the system works which they sent to explain why there will be vacuum. According to my dealer this high crankcase vacuum is normal.ĭoes anyone else have some info on if this is how it is supposed to be? It will be a huge help if some readers can check their own 3.0TFSI motors to see if you also experience abnormally high vacuum in the crankcase at idle?Īs I understand it there is only supposed to be a very slight vacuum just to scavenge any possible blowby air at idle. The fault code has gone but I still experience the high vacuum pressure in the crankcase. I had the PCV valve and PCV pressure control solenoid replaced by the dealer. I also had a PCV fault code and I understand that this combined with the excessive vacuum are signs of a faulty PCV system.
It requires a force of about 2 to 4 lbs to open it. This is noticeable when you remove the oil cap as it is difficult to remove whilst the engine is running. My 3.0TFSI (Supercharged) engine has a high level of vacuum in the crankcase. I am hoping a couple of readers can help me out!
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