Idle running rough - faulty PCV valve?

Hi everyone,

"Recently, I've noticed that the idle speed on my EOS is unstable. It's not always visible on the tachometer, but you can feel occasional jolts or vibrations from time to time."
I read the idle speed data using VCDS and logged it, setting a marker each time I felt a jolt. The markers and downward RPM spikes correlate well. These spikes represent a measurement of approximately 720-730 RPM instead of the average of 760 RPM.
In addition, the EOS requires slightly more oil than before.
I haven't noticed any decrease in performance, but I also haven't checked the readings or performed any test drives yet.

Could it be that the PCV valve (positive crankcase ventilation) is defective? Is there a way to check this more precisely?

Hi,

Quote:

From time to time, you feel a jolt/vibrations

.
Have you already ruled out issues with the air conditioning compressor or electrical loads?

Quote:

Could it be that the PCV (Positive Crankcase Ventilation) valve is defective? Is there a way to check this more precisely?

"Sorry, I haven't used this with a TSI before..."

Best regards, Rainer.

I would rule out load as a factor. For example, I've also logged the engine load and ignition timing before. The engine load was constant, and there were only minimal fluctuations in the ignition timing. Also, I was parked in the garage with the door open, and the air conditioning was turned off.
Ah yes - occasionally, the "pop meter" and measuring device detect a "surge" every 5-10 seconds.

Thank you for the hints .

Hi,

While I can't quite imagine how the PCV (Positive Crankcase Ventilation) system could only occasionally cause a drop in RPM, I think there's some very good information about it here:
http://20tfsi.blogspot.de/2013/11/guide-pcv-ventil-tauschen-20-tfsi.html

BTW: I would avoid getting a PCV fix for as long as possible.

"Edit: Please check the lambda control factor in MWB field 3, along with MWB 3 and MWB 31 (actual and target lambda values). This might give you an idea of whether the interruptions are caused by the lambda control loop, especially if the control factor is at the edge of the target range (-10.0 ... 0.0 %) or significantly outside of it."
However, most of this is just guesswork; I don't have any personal experience with these kinds of problems.

Just a quick update.

I logged the specified engine parameters while idling and under acceleration at a standstill, and I didn't observe any anomalies in the lambda values.

I also removed the cover to access the hose leading to the PCV valve, and I blew into the hose. The PCV valve is sealed .

"I had previously performed an oil change. Afterwards, the vibrations felt noticeably reduced, and in some cases, were no longer present. I repeated the measurement using VCDS and calculated the rate of change in RPM (RPM gradient), which is now significantly lower. Before the oil change, the peak values were between -80 and -123 1/min/s. After the oil change, the peak values were approximately 50% smaller, ranging from -40 to -55 1/min/s."

The oil level was already at a similar level before the oil change.

Thank you for the information, even though it doesn't provide a clear explanation for the problem .

For now, I'll just be observing. Therefore, I won't be exchanging anything at this time.