VeeDubTDI said:
Have someone look to see if it's open or closed when you try to start it. It takes vacuum to close it... the ASV is normally open, but I'm more inclined to say that there's air in the fuel system.
Have you checked the timing?
If it won't run for more than a split second, you can't really check timing.
Damn electronic TDIs...
When it does run, for that split second, how does it seem? Rough/smoky/sputtering or running sort of OK? After that, if you crank it, does it act completely dead or does it seem like it almost wants to run? Smoke? Signs of life?
If it starts up well, then suddenly kills and acts completely dead when you try to crank it further, I would suspect the anti-shudder valve. You can pull the vac line off it to rule it out as a possibility.
If it doesn't start great, runs funny, then tries to start and smokes etc later but won't stay running, then you are most likely looking at a timing issue. Go back to square 1 and check that your basic timing is correct at the cam and at the pump. I find that when I set ALH motors very carefully in basic timing, their actual timing in VAG-COM ends up perfect almost every time and needs no further adjustment. If you do that basic setup right you will get it very very close, certainly close enough to run OK. You may be a tooth off somewhere.
It can take a while to get all the air bled out of the injector pump. Have you tried force-feeding it with a small low-pressure electric pump (Facet or similar) in line before the filter? That can be very helpful in ensuring a good bleed.
Go into VCDS with the key on and engine off and look at all the sensor value that the ECU pays attention to at startup. You are looking at temperatures (air, fuel, coolant), barometric pressure, and other external conditions (the motor does not care about MAF, O2, etc at startup). Ensure that all your values are reasonable and nothing is way off. If the engine is cold, for instance, all three temp readings should be very close to each other.
If nothing seems to be working, try unplugging the coolant temp sensor (at the rear of the head underneath the coolant manifold piece back there) and starting it with that unplugged. That makes the car think it is at the north pole and goes to full extreme cold setting, gives you lots of timing advance and fuel which will help it stay running at least long enough so you can check timing and figure out what else is going on.
