Hey ppl, I've been having a stupid P0171 system too lean (add) code since last week when I replaced one of my hoses that connects from the back of valve cover down to the crank case. I'm running a 1.8T quattro 6 spd, diode modded ( don't hate, it works when done properly) 17psi, 3 degree timing adv., TT dv valve, custom 3" magnaflow exhaust w/ highflow cat, TIP, TurboXS MBC. I've been running this set up for about year now with no issues at all, including fueling.

After I repaired the hose Mentioned above ( never had the code when the hose was disintegrated either), I notice my fuel mileage went to **** and my boost wasnt building as fast. I checked for vacuum leaks with ether and got nothing, cleaned and tested my maf and all is good. I know the P0171 indicates a lean mixture at idle and I'd assume a vacuum leak but my boost gauge tells me -22inHg which is normal and 2.8g/s from Maf. I notice that 032 block on vagcom read something like -9% and 0% which also indicates leak at idle but when I reset my ecu and went for a drive it was just like nothing had happened. The car idles fine, and is normally peppy but when he code was registered, it was super sluggish. Also, my MAF tells me it sucks in 149g/s at 4300rpm in 3rd. Still about normal. Any ideas will help!