2nd VNT17 dead

So, question for y'all.

Both turbos blew at WOT, but never had issues before then. One blew around 3000 RPMs, then other at 4500.

What "foreign" object could possibly trash these turbos? The only thing I can think of is carbon buildup inside the head, or a piston ring, or maybe a bearing.

But in the latter two cases the engine continued to purr just fine afterwards, and after the first one was replaced, no additional oil usage.

In other words, it's gotta be WOT related.

The only other clue is that I had hesitation off idle. Really had to feather the clutch to get the car moving, and I knew there was something wrong - thus the reason for taking the logs in the first place.

I think it's oil starvation of some sort. Oil at idle wasn't getting to the turbos, making them sticky. That's my best guess at this point, but who the hell knows.

We're all speculating. Including me. Have an expert inspect it (or both).

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Check oil return line as well.

I will throw this out there... was the air filter brand new when the first turbo was replaced? Was it replaced before the second new turbo was installed? How about the intercooler was it meticulously cleaned before the first replacement turbo was installed, and especially before the second turbo was replaced? I know we only think of the IC as flowing air in one direction, but that is not always true. If you have ever heard of turbo surge think of it this way: the turbo is up on spool and we let off of the throttle, the engine drops off RPM much faster than the turbo does causing a rush of air from the intake manifold going back through the IC causing surge, we would not normally hear it occur in such a small turbo, but it does occur. That is why there are so many posts regarding FOD damage caused by failure to remove the IC and piping to the turbo. This may not be what happened in your situation, but I read this whole post and I don't remember seeing it mentioned.

Let's not confuse things...surge is caused from too little mass air flow, and too high a pressure ratio. The vanes stall like an airplane wing.
cheers,
Douglas

I just don't see how, on these little engines that you could get enough back flow up hill to move something hard or substantial enough to destroy a turbo. Yes I've walked flight lines looking for anything big enough to pick up. Maybe if it had a throttle body but the turbo is always moving air away from the compressor wheel always and forever amen.

My money is on either an oiling issue or turbine over speed

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So, used good VNT15 installed. 10 minutes down the road at half throttle - BOOM!
Factory oil line. Yeah, running rc4 still (don't have a stock tune) but still - half throttle?

Gotta be overspeed. What on earth could cause this? N75 new, Pierburg MAF new. All vacuum lines look right. Best guess: tune is bad.

Next step: get a stock tune and run that for a while and get some logs. Don't really want to pull the injectors (.216s), but may have to.

I figure with time, turbos and other expenses I'm out about $3,500 this year already.

Maybe the MAP sensor is bad, and is reporting a lower pressure than the actual pressure, so the ECU runs the turbo too hard trying to make boost?

Interesting suggestion. Been running a 3-bar MAP for years, with my stock VNT15, even before I moved to a VNT17 so I don't think that's it. BUT who knows at this point! Worth looking into.

It would be kind of a hassle, but if you could set up an apparatus that you can pressurize with a bicycle pump or something, and connect the MAP sensor on it while it's still connected to the wiring in the car, then you could use VCDS to see if the MAP sensor reading is the same as the pressure in the test device.

For every turbo you use to just blow up almost immediately, they must be running way too hard..... but why is the question, of course.

You've checked the vacuum lines, but maybe check again just in case. If the turbo was stuck on full boost all the time, then that would probably kill it pretty quick.

Judson, sorry to hear the VNT15 blew up as well. I just wanted to update you on my VNT17. It has been working fine for about 5 weeks and 1000+ miles. I have done quite a few WOT tests without issues. My previous VNT15 blew itself in half, which is why I am updating you. I am using a braided steel oil feed line as well. I don't have a tune though, but I do have 1019 injectors.

Thanks for the info.

Something is extremely not normal. These cars aren’t designed to blow up turbos but run reliably for a stupid long time.

Sorry to hear about the issues you're having with the VNT-17 turbos. It's gotta be pretty frustrating going over everything that you think it could be, but you're still blowing up turbos.

I know this isn't going to be the cheapest solution, but I think you're going to have a tough time blowing up a GTD1752VRK. http://www.turbo-upgrade.com/produse/gtd1752vrk-with-manifold-for-19tdi-2wd/2136/
You get the responsiveness you're after with the VNT-17, but the power of GTB1756VK, so you get the best of both worlds, plus I would think you would have a pretty difficult time grenadining it.
It has to cheaper than replacing turbos every week.

Smoked three TC's.

One wonders if there's a problem other than the TC's themselves.

RC4 on a VNT 15 is asking for trouble no matter where you are from.

the vnt17 can handle it with the right tune, nozzle setup, exhaust, intake and MAP sensor.

have you been in contact with Jeff at all in this process?

Called him twice yesterday. No answer. According to his voicemail, he was out for about two weeks before that (I believe on vacation).
We didn't suspect the tune until this vnt15 blew. I've been running his tunes for about 15 years now without issue.

I don't think it's the tune. RC4 is typically 22 PSI, and if you weren't at full pedal you wouldn't get there. A good VNT-15 can run 19 PSI without issues, and will spike higher without damage. Something else is up. MAP may be an issue.

Mike_04GolfTDI said:

Maybe the MAP sensor is bad, and is reporting a lower pressure than the actual pressure, so the ECU runs the turbo too hard trying to make boost?

Click to expand...

This, or a boost leak somewhere causing the MAP reading to be lower than actual.
Do you have a gauge on your dash?

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First, thanks again to alll of you who have commented. Much appreciated.

I have a boost gauge. Been watching it closely! I never saw an overboost condition when running the VNT17s. Not once, not even during a full throttle run.

I think I asked my mechanic like three times if he checked the boost/intercooler tubes, and he said yes every time. I kept thinking it had a to be boost leak, leading the boost gauge to underreport how much boost, and for the turbos to overspool in an attempt to meet requested.

This is why I don't get this issue. Really really screwed up.

Question: Would running rc4 with a stock MAP sensor cause an issue? Would boost just be limited to 2.5?

Thanks.

Judson said:

Question: Would running rc4 with a stock MAP sensor cause an issue? Would boost just be limited to 2.5?

Thanks.

Click to expand...

The boost would be limited to 2.5/3=83% output. Running a 3bar sensor on a tune written for a 2.5bar sensor would show only 83% of the actual boost. This would cause the turbo to overboost without knowing it.

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The reason for asking is that I don't have a stock tune to test with.

So, from your answer, max boost would be 24*.83=about 20psi. Maybe we could run that for a while, and hopefully not blow another effing turbo.

Folks - another question. It just occurred to me that somewhere I have the SKC to my newish cluster.

If I put my stock ecu back in, what's the procedure to match the two together? I read through some info at ross-tech, but it's confusing. I believe my cluster is immo3, as it's a sport cluster I got off of these forums (beautiful thing it is compared to stock).

If I can get the two to match, then I could run this with a stock MAP and be in great shape to do some logs.

If your stock ECU has immobilizer deleted, it's plug and play. Beyond that, I can't help much...

JDSwan87 said:

If your stock ECU has immobilizer deleted, it's plug and play. Beyond that, I can't help much...

Click to expand...

This is not always true for odd reasons, however, possible. The Key matching the Immo in the old cluster is the important part on that, unless somehow you switched keys with the new cluster...

Garrett got back on the first VNT17 I blew back in April: overspeed. Not surprising at all.

Dropping stock MAP and stock ecu with mechanic today. He's busy, so it'll be a while before he can recode things and get it back on the road to do some logging.

OK, folks, well, another good used VNT15 is in, the stock MAP is in, and now waiting on a flashzilla unit plus a Malone performance tune. Hopefully end of next week I'll be doing some *gentle* driving and logging!

USPS lost my package for three days, but after *****ing at them incessantly, it was delivered to me Friday morning. Drove it down to my mechanic, who used the new flashzilla to download the current ecu software and sent the file and my current specs/needs to Malone. Received the new file today and sent it to my mechanic.

Unfortunately, it'll probably be next week before he can get at my car (and he needs to clean my intercooler again of oil and turbo bits). But cross yer fingers, I hope this does the trick. Everything else seems to be working perfectly. I mean, I'm back to a stock MAP just in case as well.

That's unfortunate news. Sounds like you have a boost leak somewhere somehow. You should do a pressure test of the boost system and see if you hear anything with the engine off. The intake manifold can leak if it comes loose and you would never hear it with the engine running.
Check the intercooler isn't damaged and leaking.
I wouldn't drive it without figuring something about it out first. 2 turbos to many to install. Overspeed has to be a leak or bad map sensor. Clogged intake will slow the turbo down not speed it up. Only overboost or a leak can cause overspeed on the turbine....



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