What is the reason for a rough idle in an Audi 80?

I have noticed a rough idle in my Audi 80 and I'm wondering what could be causing it. The car runs smoothly while driving but shakes and sputters at idle. Is this a common issue with Audi 80s and what can be done to fix it?

The most common reason for a rough idle in an Audi 80 is a dirty or faulty idle control valve. This valve controls the amount of air flowing into the engine while idling. If it is clogged or malfunctioning, it can cause the engine to run roughly. I would recommend cleaning or replacing the idle control valve to fix the issue.

Another potential cause for a rough idle is a vacuum leak. Check for any cracks or damage in the vacuum lines and replace them if needed. It could also be caused by a faulty oxygen sensor, so it's worth checking that as well. An Audi mechanic can diagnose the issue and recommend the best course of action.

If your Audi 80 is equipped with a carburetor, a malfunctioning or dirty carburetor can cause a rough idle. It may need to be cleaned or rebuilt to fix the issue. You can also try adjusting the idle speed screw to see if that improves the rough idle.