No boost issues

First post, been using for years.

I have an 03 ALH thats been down for a few months (stuck glow plug, couldnt salvage the head). Went ahead and rebuilt the turbo while it was out and decarbonized the intake components (couldnt fit my pinky inside it due to build up....). Swapped everything over and reassembled and now i have no boost.

I verified vacuum hoses.
I pulled apart all the intake components and cleaned them and cant find a boost leak.
Pulled around a liter of oil from the bottom of the intercooler
Turbo rotates freely and while i had the parts off, i verified that its actually push air through (although not much)
VCDS actual boost starts around 1000mbar and decreases to maybe 800 as the engine uses the air.
Turbo does rotate and blow, but you cant hear it like normal when driving, and its completely gutless.

I have vcds but this is the first time ive been stumped.
Any help is appreciated.

Check there's vacuum to the turbo actuator.

Tee a vacuum gauge into the line and start the car.
You should get around 10 inches of vacuum.

Make sure the arm the actuator attached to moves.
If you go to drive the vacuum should drop at first.

If you have a vacuum pump check the actuator arm starts moving at 4 inches and is full at 18 inches or so.
It should also hold vacuum.

There's a VW bulletin about the actuator rusting inside and not working correctly.

Who rebuilt the turbo, and what was done to it. It is possible to put the control ring in upside down, so the vanes don't open and close properly.

Ask me why I know.

I do have good vacuum readingsand mine actuates between 2.5 - 18 inch vacuum so i didbt see anything outside the norm. I even pulled the turbo again to make sure the vanes moved properly and that the ring was actually on all the vanes, but everything looked good, lubricated vanes anyway, reassembled and nothing changed.

Pudman, do you have any more info on which side should face what? Does this sound familiar to you? I did the rebuild. Wasnt a whole lot of info out there on vnt rebuilds to the level i wanted, so i went for it. Prpbably should have taken a lot more pics on disassembly, but hindsight and all. From what i remember i put the ring on so that all vanes aligned to center, then put it on and assembled completely....This is the first time that i cant figure something out without forum help.

Did you tee into the actuator line to check the vacuum in operation getting to the actuator?

In the control ring there are two slots near the actuator lever; a long one and a short one. As you face the turbo the long slot should be on the "left" side of the arm. Otherwise the turbo will not be able to spool to full boost.

Just from reading it seems the turbo is not especially user rebuildable. There is certainly some good you can do in there, but some of the bits need fine balancing and fitment to allow the 120,000 rpms those things spin at. Not trying to discourage anyone, some are successful.

Wonnebar: yes, i T'ed in and didnt see anything that caught my eye, also checked the actuator isolated to verify range. Checked fine.

Nevada: thanks for the info, guess ill be repulling that guy outta there to check -.- will probably post a few pics just to make sure its right.

Bob: i really couldnt find much on the whole process or anything technical in nature regarding vnt servicing. But with as much oil that i found everywhere, and since i was already swapping the head, figured why not. If i get another 20k out of it, ill take it.

Ill pull the turbo probably on sunday afternoon or monday, depending on the ferry getting out of here. Im at a wedding this weekend in the San Juan Islands.

Aljefanfrey said:

Wonnebar: yes, i T'ed in and didnt see anything that caught my eye, also checked the actuator isolated to verify range. Checked fine.

Click to expand...

If you didn't get vacuum there with the car running the actuator does not move as needed.

Wonnebar, sorry for the ambiguous answer. When i said nothing caught my eye, i meant it appeared normal. I have vacuum and can visually see/feel the actuator moving when the car starts, full motion. Nevada was right, i did put the ring on backwards. I started the car and i actually heard the turbo for the first time ib a while, sounded normal. Got excited and drove it around, but then still no power and couldnt hear turbo. As i sit here in front of VCDS im now (starting today) throwing a maf code, and i confirmed its going out with a meter. Would this cause my turbo problem to persist after the VNT ring correction? Replacing tomorrow regardless, i just need a glimmer of hope before my wife tells me to buy a new turbo...

OK, just wanted to make sure.
Go for a ride with the vacuum gauge tee'd into the actuator. The vacuum should be about 10 inches at idle and drop when you take off.

Try unplugging the MAF and go for a ride.
I think if you get more power then it's bad.
Doesn't make sense to me but I guess it sends bad info to the ECU.

Ok, i did have a bad maf (might have made it through summer, intermittant code). On the drive home i got a control pressure negative deviation, but it wont come back.
Ill see what i can do with the vac gauge when im not exhausted (hopefully tomorrow).
I do have a lot more smoke than usual, but i think thats expected right now.
Also i swapped my egr and n75 just to make sure.

Fun little tidbit though that has been kinda bugging me.... when i had my daughter romp it up to 4K rpm and then drop the pedal to 0, it actuated my antishudder valve. Granted i dont do a lot of throttling from the engine bay, but can someone tell me if this is normal?

For what its worth im prpbably going to change all the vac lines out for high temp silicone if anyone knows the size and qty needed.