Catastrophic VNT 17 failure

So I pulled the turbo, cleaned the vnt again and set the actuator to lift at 4. It took one full turn for it to lift at 4. It now hits the stop at 19. Still getting overboost at high rpm wot.

Requested boost maxes out at 2050mb and actual is approx 2500mb when the limp mode hits. I had seen the actual boost hit 2599mb when the actuator was lifting at 3, I guess this is the limit the 2.5 map sensor can read. So it does seem to have dropped a bit.

Do I need to lengthen the actuator a bit more, maybe to lift at 5? Or is this a normal situation when a vnt17 is installed and the ecu still think a vnt15 is installed?

Any info appreciated.

What actually triggers overboost, i presume its a certain difference between requested and actual for a certain amount of time? Anyone know the exact figures?

I have read and re-read, and re-read this thread, and something isn't making sense to me, actually a couple of things have me scratching my head; the long discussion about how much difference in the way the turbo will behave if the actuator is set at 3" Hg versus 4" Hg, versus 5" Hg. RyanP, I know you know your stuff, I don't and that is why I am wondering about the "...are you sure that is long enough..." question. Having just got done resetting the actuator rod length on my new 17/56 to where it start to move around 3-3.5" Hg, and hits the stop at just past 18" Hg.
If the actuator is set too short there might be some terrible spikes at less than WOT, and if the actuator is too long (provided the vacuum system is in top shape) boost might be delayed or not reach requested boost, is this correct?
I guess what I am not grasping is why 3" Hg apparently dangerous to your turbo/engine?
My current tune is still for the vnt-15 and .205 nozzles I used to have; basically a Stage 3 18 PSI tune. With significantly more air and significantly more fuel, I am having no spikes and no boost creep, and my requested and actual boost are still the same as they were before. With a 10 mm increase on my compressor wheel and my lift point at ~3", why am I not having any spikes and why is my boost following requested?
I am being sincere here, what part of the conversation am I missing? Other people are having massive issues and catastrophic failures due to excess boost on their vnt-17's and I am not?

Well, I figured I would bring sexy back and resurrect this thread. My VNT17 has a catastrophic failure. I’m hoping the car isn’t dead for good. I took it to the dealership because I was 850 miles from home when it happened. Told them it was probably better not to drive it, that I didn’t want metal in the oil or intake... Well, the tech drove it. I ordered a new VNT17 plus. I hope it does better than the turbo currently in the car.

FixItDaily said:

Well, I figured I would bring sexy back and resurrect this thread. My VNT17 has a catastrophic failure. I’m hoping the car isn’t dead for good. I took it to the dealership because I was 850 miles from home when it happened. Told them it was probably better not to drive it, that I didn’t want metal in the oil or intake... Well, the tech drove it. I ordered a new VNT17 plus. I hope it does better than the turbo currently in the car.

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They DROVE it? Even after you told them the turbo grenaded? I'd do a compression test, just for safe measure.

I would suggest pulling your intercooler and cleaning it meticulously and wiping the whole tract out. There may be chunks and slivers caught in there that could work their way to the intake.

Nero Morg said:

They DROVE it? Even after you told them the turbo grenaded? I'd do a compression test, just for safe measure.

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Yep! Tech proudly told me it ran really well. Asked if I wanted to sell it. These guys kill me!

I ordered the VNT17 Plus hopefully it lasts longer than the last one! I’m going to install a new MAF and change the N75 valve. Checked the vacuum system and the only leak was a very slight one in the N75 valce. Hope there’s no damage to the engine.

FixItDaily said:

I took it to the dealership

Well, the tech drove it.

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I hate beating a dead horse, but that's the VW dealership in 2019 for you. Avoid them at all costs.

I hope the engine ends up okay as well.

jerrymander said:

I hate beating a dead horse, but that's the VW dealership in 2019 for you. Avoid them at all costs.

I hope the engine ends up okay as well.

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Yeah, it really surprised the heck out of me. Especially when he said,”you were right, it doesn’t make any boost...” I’ve not had good luck with this car and mechanics either, the best work that’s been done on the car is the work that I’ve done myself. It’s been to three other shops besides the dealership and wow! All I’ve done is waste money and not get results. The Bremerton to Tacoma area is not a great place to have work done.

But... The tech that did end up working on the car seemed pretty legit. Then the parts manager hooked his VCDS to the car and we went for a drive. He showed me the “IQ” I believe, it was running at 2.2 to 2.4 so he changed the number in the ECU from 38784 (Don’t quote me) to 38750 and now the car is running at 4.0. He said it would make the car a little fatter which should be good since I have 850 miles to drive from Idaho Falls back to Fort Lewis, WA.

I’m a little worried that with the new VNT-17 Plus I could run into complications if I were to drive it at all hard. I’m sure an updated tune is in order. As it sits at approximately 1/2 throttle and 3,000 RPM the car was seeing 2400 millibars. After subtracting 14 psi for atmosphere that puts it just over 20 lbs of boost. I think this tune with the regular VNT-17 was seeing 24-25 lbs of boost. So not something I want to mess with until I’ve checked all the boxes.

P.S. I’m going by memory of n the IQ, it may have been 32750 I can’t remember.