Help...boost nearly gone and flapping sound under acceleration

[dankaudi]

Driving home yesterday, boost dropped from normal 17-19psi to 3-4psi...under WOT in 3rd and 4th I can climb to 9 psi around 5500rpm...figured it was boost leak so I did check sure enough the pipe off the turbo was partially off...fixed it said hell yeah and went for a spin...boost still not back, did another boost leak check to ensure no other leaks, and there were none...took n75j valve off and I put the greddy profec back on...boost still not back...actually lower...when I was under there I noticed the SAI pipes intake was missing ( i had a small cone since I have a K&N cone)...unplugged SAI and still boost is gone.e flapping sound sounds like a card in a bicycle wheel.....this leads me to believe my turbo is bad (no smoke, nothing out the exhaust), wastegate is stuck closed, or SAI sucked something up since filter was gone...anything else anyone can think of??? No CEL except for turbo underboost code which I have had since i did the FMIC...turbo is a k04 off s3 i believe, and is about 2000 miles old...any help appreciated.

[Saturnine]

Check your dv would be my guess

[dankaudi]

Checked itout seems good... I think the wastegate is stuck shut and that's the flapping I'm hearing...thoughts?

[old guy]

Have you reset any codes since the initial incident? Are you running the N249?

[dankaudi]

Yes I have reset them numerous times, underboost is only code I am throwing...yes I have the n249 valve still in place...fluttering is at idle as well just more prevalent with acceleration...pulled on wastegate arm, it has almost no play, think that is my problem, should I disconnect n249?

[old guy]

I doubt it's the N249 but it's one variable that is easy to eliminate. Run the DV directly to the manifold nipple and see if it makes any difference. Instead of futzing around underneath the manifold just cut the DV line in front of the block and hook it to the manifold nipple. Use a hose barb connector to connect the other cut end to the line you pulled off the nipple. That way it is very easy to reverse and doesn't require standing on your head underneath the manifold.

[skiibum]

I had a similar situation recently and it was the diaphragm on the waste gate actuator. It took forever to pinpoint and diagnosis. The dealership would say you need a new turbo, but you can buy the part separately on ECS if this turns out to be your issue.

[Dwaller]

i had that exact problem it was the dv!!!!

[dankaudi]

Ahhh problem solved...Took turbo off car today, as soon as I pulled it I saw my problem...wastegate actuator arm was slanted, causing the wastegate to not open...you could not push it open unless u gave it brute force, which I did not cause that's all I need...repositioned it back to normal by loosening compressor housing and realigning...wastegate opened with a slight tug perfectly...took her for a spin and all is good...sidenotes: did not tighten intercooler pipe to turbo and got a great pop when I let off gas after 45 sec, tightened, fixed...oil filter was loose, explaining the oil all over my engine, replaced, fixed...fluttering was boost going into wastegate and wastegate not dumping into exhaust, fixed with repositioning arm...took about 5 hours total with futzing around and taking apart old k03 cause I wanted to swap housings...also bought 5th bottle of pentafrost, guy gave it to me free!!! Whole day costs $20 for oil and filter...