Sudden turbo noise and no boost overnight

[Tristan265]

I have an 04 Jetta tdi BEW that I recently replaced the engine due to a turbo that grenaded. I replaced the engine and put on a used Vnt-15 turbo and it ran great for about 80 miles. I went to startup my car one morning and noticed a weird sound (like a hellcat supercharger whine) when accelerating and a lack of boost. When I parked it the day before it ran just fine and no weird noises. Did the turbo suddenly fail overnight or could a bad n75 valve or vacuum lines cause no boost and a whine? I checked all of the boost piping and do not see any cracks or any pipes that popped off. Any ideas?

 

[lemoncurd]

like a hellcat supercharger whine

generally this is associated with the death of a turbo

did you prime the turbo before firing the engine up?

 

[Tristan265]

generally this is associated with the death of a turbo

did you prime the turbo before firing the engine up?

I did not…

 

[jetpackjbd]

Yeah, it sounds like the turbo might’ve run without oil for a bit from a lack of priming, wore quickly, and recirculated abrasive metal flakes until it failed. Next step is to take a look at the turbo and see if there’s any play in it. Engine oil could be compromised too, change it asap

To be clear, I’ve never installed a turbo and wouldn’t have thought about oil priming either. You don’t see it in car build videos often.

It’s possible that you’ve got an air leak somewhere that’s causing high pressure air to screech, it’s odd that the turbo would fail without any signs of issues before. Pressure valve could be stuck open, or some rust finally penetrated through something and created a leak

 

[Tristan265]

Yeah, it sounds like the turbo might’ve run without oil for a bit from a lack of priming, wore quickly, and recirculated abrasive metal flakes until it failed. Next step is to take a look at the turbo and see if there’s any play in it. Engine oil could be compromised too, change it asap

To be clear, I’ve never installed a turbo and wouldn’t have thought about oil priming either. You don’t see it in car build videos often.

It’s possible that you’ve got an air leak somewhere that’s causing high pressure air to screech, it’s odd that the turbo would fail without any signs of issues before. Pressure valve could be stuck open, or some rust finally penetrated through something and created a leak

I think your theory is correct. I took the turbo off and the bearings are definitely worn. I will make sure to prime the next turbo I put on. Thanks for the help!

 

[jmodge]

Turbo priming is overrated. Pull the boost hose off and look at the impeller. If it shows signs of contact with the body it's trash. Drain the intercooler and post how much oil you collected out of it. If you have questions about whether it is pumping oil past the seals, you can run it with the hose off to see what it's doing. Also check for boost leaks, can't really know what the "hellcat whine" sounded like, but it sounds like you're describing a seizing turbo, not a boost leak. Did it smoke? BEW's don't have vet 15's on them, I don't think. I hope you flushed the intercooler after the previous turbo failure, if it spread metal. I'm not sure what your previous "turbo failure" consisted of. Some more info is needed

 

[jmodge]

I think your theory is correct. I took the turbo off and the bearings are definitely worn. I will make sure to prime the next turbo I put on. Thanks for the help!

How did you determine it's got worn bearings? It should not move in and out, wiggling it side to side means nothing unless it shows contact with the throat.

 

[Tristan265]

How did you determine it's got worn bearings? It should not move in and out, wiggling it side to side means nothing unless it shows contact with the throat.

After first turbo failure I cleaned out IC and all boost piping. Your correct BEW’s don’t come with Vnt-15’s but they can be fit on all you need is a different pipe going to IC and smart actuator swap. Compressor fins show signs of wear like it was rubbing against housing. That must’ve been the whine noise.

 

[jmodge]

ok, sounds like you have a handle on it. Vnt-15's are pretty old at this point, so that one was probably ready to give up the ghost. That feed line has instant pressure to it, I've never bothered to prime one. If you want to though, shut the fuel off and crank it for a few seconds.

 

[Tristan265]

I got one of my previous turbos fitted with a new x-man turbo core and installed in my car. I also hooked up a boost gauge since i have been struggling with turbo problems. Today i took it for a drive and it was running so much boost it maxed out the gauge (30psi gauge) and shot the hose off of the gauge. I then did a boost log with vcds and it showed the boost going all the way to 45psi! I am not sure if i am reading the graph correctly but it looks like that is what the computer is requesting. Here is a link to the boost log. The turbo core i installed is rated for 24 psi max. I drove it for about 20 minutes. Do you think i caused serious harm to the turbo? Could i just install a blow off valve to keep the boost down or will that trigger low boost codes and limp mode? Otherwise i believe will need to get it retuned but i would rather install a blow off valve as it would be cheaper (and sound cooler ). Anyone have experience with blow off valves on TDI's?

 

[Tristan265]

Just a thought. Could the boosting to 45psi be caused by improper Vnt stop screw or Improper actuator rod length?

 

[jmodge]

Not if the tune is calling for it. How many miles have you personally put on this car before the 1st turbo went and what turbo was it? Looks like you have some mismatched hardware/software

 

[jmodge]

I think you have to subtract atmospheric pressure from the boost specified. If that's the case it's calling for approx 25 psi around the135.50 time stamp. Too much for the the vnt-15.

 

[Tristan265]

Not if the tune is calling for it. How many miles have you personally put on this car before the 1st turbo went and what turbo was it? Looks like you have some mismatched hardware/software

I personally put about 500 miles on the car before the first turbo blew up. The guy i bought the car from said he drove it daily about 100 miles to work. The turbo that was on it was a Vnt-17.

 

[Tristan265]

I think you have to subtract atmospheric pressure from the boost specified. If that's the case it's calling for approx 25 psi around the135.50 time stamp. Too much for the the vnt-15.

That makes sense. The turbo core i installed is rated for 24psi so that should be close enough for tuning wise id think.

 

[jmodge]

You probably had problems from the get go, whether you realized it or not. It sounds like there's probably something the PO didn't tell you.

Two things going on here that seem suspicious. you could clear one up by posting a picture with ID tag of the cartridge you installed. You called it a VNT-15? 18 psi with spikes to 21 are about all they can safely sustain. Or maybe I'm confusing the first cartridge with the second.

The other is 30 plus psi on the boost gauge. I would think the MAP would have read that and signaled the ecu to cut fuel and go into limp mode. If you research it you can probably come up with a resistance reading or some way to check the MAP to see if it's functioning correctly. Or the gauge isn't functioning correctly. Something is amiss there it appears.

 

[Tristan265]

Two things going on here that seem suspicious. you could clear one up by posting a picture with ID tag of the cartridge you installed. You called it a VNT-15? 18 psi with spikes to 21 are about all they can safely sustain. Or maybe I'm confusing the first cartridge with the second.

Sorry. To clarify the first turbo (the one that was in the car when I bought it) was a Vnt 17 ID tag reads 778445-5002S. After that one blew up I installed a Vnt 15. After that one blew up I rebuilt the Vnt-17 with a X-man turbo core gt1749vb 721021.
1. Vnt 17
2. Vnt-15
3. Rebuilt Vnt-17 (currently on car, just installed over the weekend)

 

[Tristan265]

The other is 30 plus psi on the boost gauge. I would think the MAP would have read that and signaled the ecu to cut fuel and go into limp mode. If you research it you can probably come up with a resistance reading or some way to check the MAP to see if it's functioning correctly. Or the gauge isn't functioning correctly. Something is amiss there it appears.

I looked back at my video of the boost gauge. The line popped off the gauge at about 25psi. (Thought it was 30 because the boost climbed quick) I forgot to put a clamp on the hose going to the gauge

 

[Tristan265]

With that being said does the boost log look like everything is ok for a Vnt-17 turbo? I want to drive the car but I also don’t want to ruin another turbo.

 

[Dannyboy]

Turbo priming is overrated.

Agreed.
If the turbo is new, different story.
Putting on a used turbo is always a gamble without knowing how vehicle it came off was running.
Also it's no different to any turbo vehicle that's been sitting around for a period of time.
Unless you pin the accelerator on startup your not going to damage it any more than normal wear and tear.

 

[BobnOH]

These turbochargers are built hell-for-stout. Have you figured out why they keep failing?
Lack of oil or wacky controls are all I can think of.

 

[Tristan265]

Have you figured out why they keep failing?

I’m thinking it’s the tune

 

[Tristan265]

Here is a video of the turbo overboosting
I’m not sure if it is a faulty sensor or the tune that is making it overboost so much. I’d think the ECU would throw it into limp mode but it did not.

 

[Tristan265]

I unplugged the MAF and took my car for a drive. It was noticeably slower but did not overboost while still hitting max boost (around 24-25 psi). Could this mean that the tune tuned out the MAF and are supposed to leave it unplugged? Or could it be that the MAF is bad and causing the car to overboost while plugged in?

 

[burpod]

it looks like it's calling for too much vane closure, for those heavy fuel requests... a stock-fueled BEW tune should not be causing boost spikes to 28+ psi unless the tune isn't good and/or have some hardware issues too. have you checkd that the set screw is in factory correct position? and 18hg to hit the set screw? one shouldn't have to use boost valves to control boost. the tune should be able to do the best boost control if it's done right (and of course no other issues)

 

[burpod]

take a log of 011-001-004 with some varied pulls. make sure to use TURBO mode when logging in the BEW - much faster sample rate, better data. you have to click TURBO before you click "Log" in order to activate it. if you don't, you have to back out and redo it.

 

[Tristan265]

have you checkd that the set screw is in factory correct position? and 18hg to hit the set screw?

I haven’t touched the set screw as I heard those are set from factory correct (x-man turbo core). When I put the turbo together and checked the actuator I remember it did hit the stop around 18hg but I remember it also cracked open around 1-2hg. I’ll double check it.

 

[Tristan265]

take a log of 011-001-004 with some varied pulls. make sure to use TURBO mode when logging in the BEW - much faster sample rate, better data. you have to click TURBO before you click "Log" in order to activate it. if you don't, you have to back out and redo it.

Do the logging with MAF plugged in I assume, right?

 

[Tristan265]

take a log of 011-001-004 with some varied pulls. make sure to use TURBO mode when logging in the BEW - much faster sample rate, better data. you have to click TURBO before you click "Log" in order to activate it. if you don't, you have to back out and redo it.

here is the Log on I took on a test drive

 

[burpod]

you have something very wrong. that log looked a lot different. yu're not making any boost