There is no iac it uses a throttle servo to adjust idle heres a tip I found for code P0171 let me know what you find.
If you have a B7 (2005.5+) Audi A4 with the 2.0 that has a rough idle and complaint of hesitation along with a lean code and other codes (mine was a misfire, fuel pressure reg code, and idle speed code). Try and take the oil cap off when it is idling. If you cannot or when you do it sucks a rush of air into the engine then you have a PCV issue. These PCV's are crappy and have been revised (so I hear). It is located under the engine cover on the drivers side of the valve cover (see pics). The normal problem is they crap out from the boost pressure and then leak boost into the engine giving you a lower than expected boost pressure. Some times (like this) they can be damaged enough that they give a straight vacuum to the valve cover. Although they shape and design might be vastly different then that of other normal PCV's it is still suppose to perform the same task. There are after market tuning companies that make full metal versions of this unit that retail from 99-150 dollars. The dealership had them for about 60 bucks. Your choice.
October, 1, 2012 AT 1:13 AM
Wow lots of suction in the oil cap. I hope to replace the PVC tomorrow. I'll keep you up to date on what I find. Are the pictures located somewhere else?
October, 1, 2012 AT 1:35 AM
Heres the pics let me know how it turns out.
October, 1, 2012 AT 2:02 PM
Where can the metal aftermarket PVC be purchased from? Do you have a reputable site you trust?
Also, if I went with the dealer, is there a way I can order that part online? Or do I need to call them. I live in a city that does not have an audi dealer.