Audi Repair Questions? Ask a Mechanic for Answers ASAP
Thanks for choosing Just Answer . I'm Wolfgang here to help!!Below is my first answer or request for more information. If you do not understand it, or you need more information from me, or need me to go in more detail. Do not rate yet, just reply. Put yourself in my shoes, I can not see, smell, hear, feel or touch your car, nor do I know any history on it. So take into consideration I am doing my best based on what you tell me. Also understand fixing cars often requires sophisticated tools, that you may not own. So even if you can not do what is outlined in my answer, that does not mean my answer is wrong deserving to be rated negative.
the first thing is to address the p0171 fault. what scan tool are you using ? make and model?
can you get miture readings while running ? can you emulate vag mode and do a basic settings test 107?
Please do need to see if the engine is running lean at idle or not
This is where the scan tool is absolutely necessary to read the mixture values and start to use carb spray to isolate vacuum leaks first or pinch hoses and look at the readings. Dirty test if you see oil residue around any of the breather connections is a tell tale sign of a vacuum leak/air leak.