engine falls flat with WOT

As I start out I give it lots of throttle, and its not cold. It's like I shut the key off [flat on its face]. After that it runs normal - torquy even with lots of throttle. I can't figure out what happens, because it runs normal, except when this happens.
Anyone have this happen?

That's known as limp mode.


http://forums.tdiclub.com/showthread.php?t=179589

Not really. If it runs as normal after falling flat without cycling the key that's not limp mode. If your MAF is bad and you have a MAF delete tune it'll run like crap at first and then switch to MAF delete and run OK. Jeff doesn't usually do that, however.

Not an expert but I've always considered limp mode as any of several condition, so closely related to low power they can be troubleshot as the same. It's usually some component of the engine management. Any stored codes can give a clue. There are good troubleshooting guides here and at myTurboDiesel, but do be careful what you read on the interweb.

Falls flat at WOT

This happens if I open to WOT quickly, but if I nurse it up slower to run thru the gears it's OK. 7/8 open is always good, but sometimes a quick full pedal is the problem. A full run thru the gears [like the 1/4 mile] is good because your never WOT in first from a start. Could be a lot worse issues, I know

I had a sticking turbo act this way. The vanes stick until it warms up. If I remember right I never got a check engine light but sticking vanes can act weird. I finally gave up after a few cleanings and changing parts and put another turbo in and the problem was cured.
The best way to figure this out is to have someone watch the computer with VAGCOM as you drive cold under a full load. If the boost is a lot lower than what is requested then the turbo control is the issue.

I had a similar issue, couldn't gun it, but if I was gradual I was golden. Turned out to be a collapsing vac line, I assume between the N75 and the actuator. Put all new vac lines on and it cured that right up.

Even with the old vac lines they'd hold 24inhg just fine, but couldn't do it so abruptly. Have you replaced yours lately?

Sounds like a fueling problem to me. Either a streaming injector or the pump is failing to deliver fully when requested. Look at injector balance and run a log for pump delivery versus request.