S4 Turbo Won't Start/Stay Running. AFM?
 

Hey, I'm new to the forum, so I'm sorry if something similar has been posted/answered before but I couldn't find an exact match to the issue I'm having.


Months ago I had been trying to get the car to run properly. It would start up fine but had this surging idle that I couldn't do anything about. If you tried to give it gas it just tried to stall out. That was months ago, but I felt I should include it as it might be important in diagnosing my issue.


Since then, the car has been sitting for a few months. I finally got some time and funds to work on it, but couldn't get it to start. I eventually managed to get it to start using the ATF trick. It ran rough at first, but after a few tries it managed to smooth out. However, it would only run for about 15-30 seconds before randomly dying. I could get it to go longer with a small spray of starter fluid when the RPMs started to dip since I at least wanted it to get to operating temp before it died out. I eventually gave up on it for the night since it was already late and I didn't want to annoy my neighbors any more than I already had. A day goes by and I go to start er' up, and I cannot get it to start again. I tried deflooding it and then the ATF trick to no avail. The fuel pump is on and working, and with the key ON, engine OFF, I get a little above 40psi fuel pressure. I believe, although I'm not 100% sure, when I had it running the other day I had the AFM disconnected. When trying to start the car the AFM flap doesn't move at all, and with myself being a novice mechanic at best I wasn't sure whether or not that was normal. I just replaced the leading ignition coil since I noticed the leading plugs weren't sparking. After replacing it I managed to get spark, got it start, and got it to idle properly around ~1000RPM, but since then I've been having the issue described.


Based on what I could find on the forum, I believe my issue has to do with the AFM. I'm fairly certain I don't have any vacuum leaks, although of course I'll be sure to double check. My question is, is there anyway to test or adjust the AFM? There's an adjustment screw on it, however I haven't a clue how or where it should be adjusted to. Should I just bite the bullet and get a "new" AFM for $100+? I imagine the S4 Turbo has an AFM specific to it, and I can't use one out of an S5, or a N/A. Any help would be greatly appreciated, so thanks in advance!

EDIT: Just remembered when I had it running the other night I had the AFM disconnected

Do Not adjust the air bypass on the AFM. There is a procedure laid out in the FSM to test the AFM. It's a fairly simple procedure.