AFM not opening.
 

when the car is started the AFM doesn't open for air to travel to the engine.
what could be the problem?

Huge vacuum leak, stuck/sticky AFM, or TOTAL loss of compression in your motor (but even then I'd think it would pull SOME air).

Are you sure it's not opening? Or are you looking at an electrical reading that implies it's not opening? If the latter then it could always be something wrong with the wiring (poor contacts, poor grounds, broken wires, et cetera).

oh god... it can't be total loss of compression :(
i'm sure its not opening though because we have to keep it open in order to for the car idle.

Sounds like a massive leak in your intake, is this turbo or N/A?

turbo 1988

Sounds like between the turbo and the afm you got a bad leak and it's sucking in enough air to not move the flapper in the afm

lol i just changed that piping though :\

Then check it all again. Maybe something got left open/unclamped. I only mentioned total loss of compression because I was trying to think of all the physically possible ways this could happen. I do think it's highly unlikely.

If you have to keep the flapper open to make it idle you might have a bad AFM, that's a key bit of information that would have been good to mention at the start. Test it according to the FSM.

they've all worked before so I have no idea why they stopped now :\
I clamped all the hoses down for the intake tubing, still nothing.
thanks for the help still guys. I appreciate it

How hard is the flapper to move by hand? There's nothing jamming it or making it stick is there? I can't see any way for the flapper to not move at all except for there to be a massive air leak after it some where check your entire intake piping after the afm all the way to the motor, including intake manifolds. I think some one suggested to pressurize your intake? Could have been a different thread but it's a good idea.

If he had no compression the motor wouldn't start and run whether he held the flapper open or not. The fsm test are only gonna tell him if the electronics in it are fine. Mechanically the only thing I can think of that could physically go wrong with an afm is the spring, but that would stop it from closing after it opens. Which leaves me to believe something could be jamming the flapper but he states he can hold it open and keep it running. And if it's not pulling enough air through the afm to open the flapper by itself but he can hold it and it runs then it's getting air from somewhere else = air leak, a massive one. Now if he could drive it at all and tell if it's boosting properly we could tell if it's before or after the turbo. But it's not driveable as is.

would a crack on the bac valve do anything?
I've went through the intake manifold already and resealed it and still nothing.

Well, does the AFM get stuck? Stuff like this sometimes ends up being something really stupid and you kick yourself for being such a dolt (most of us have been there). You said you have to hold the flapper open for it to idle. That doesn't necessarily mean it's supposed to open as much as it's being held open, it could mean that it's out of whack/faulty.

With filter and filter box removed look into the afm without touching it and have some one crank it, see if it moves at all, if it does it might be electronically faulty, or an electric issue anyways, see if there is anyone close to you with an s4 turbo that will lend you there afm long enough to throw it in and see if thats the issue.

Depending on location and size yes. After thinking for a few hours, unbolt it from the intake and find a way to temperarily plug the wholes in the intake manifold and try to start it. It's after the turbo, your afm might be getting a false reading due to the intake leak.