So within the last few days to a week or two, our A4 Avant 2.0t (I carpool with a family member, but use and work on it in my spare time. I have an A6) has been having a really difficult time with cold starts.

The check engine light came on Friday, code P0171 System too lean. Yesterday we disconnected and checked the MAF which was in perfectly clean condition. But on cold starts, especially in the mornings, it has been progressively having a harder time starting. It will crank 10-15 times, then get itself going. According to my brother it has surged while idling, as well as the RPMs dropping below 400 after starting until he gives it gas.

It always runs rough in the cold, lots of vibration that you can feel through the entire car. It also runs very loud, almost a knocking/associated vibration creating sound. It always goes away once the engine warms up

Again, it almost always happens on a cold start if its under about 55 degrees outside. Rarely happens if its above that temperature. I've heard it could be the PCV?Screenshot_2018-10-01-07-13-39.jpeg

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