Boost creep problem with VNT-17/BEW

pkhoury

That guy with the goats
Joined
Nov 30, 2010
Location
Medina, TX
TDI
2010 JSW DSG, 2013 JSW 02Q, 2004 Golf 02J, 2003 Jetta Ute 02J swap, 2003 Golf future 02J swap
So, it turns out I've been encountering a boost creep problem with my 2004 Golf. I've noticed it if I'm really pushing the car while towing or around 85-95mph not towing. Since I only have a 3 bar map, when I do VCDS logging of channels 10 and 11, it'll show requested boost of 2700 mbar and actual boost at 3060 bar (I'm guessing it's possibly much higher). I have about 135K miles on this turbo, so I'm wondering if this could be sticky vanes, or endlessly adjusting the VNT actuator from the factory position might solve the problem.

Since the turbo otherwise works when I'm not pushing it, I do have another Garrett VNT-17 in my mom's 2005 BEW wagon. It has maybe 7-9K miles on it total (if even that high). That has some kind of connector on the actuator, and I don't know if it's deleted by my tune (both cars have a Malone Stage 4 on them). Swapping turbos would honestly be my cheapest option at this point, anyways. I just wanted to get y'alls thoughts on this.
 

mk1chris

Member
Joined
Sep 23, 2020
Location
durham uk
TDI
mk1 golf with pd130 swap ,mk5 ppd 170 bmn daily
sounds like the vains are staying closed could be a vacuum leak or maybe n75 has a split in it which is allowing vac to pass through it
 

pkhoury

That guy with the goats
Joined
Nov 30, 2010
Location
Medina, TX
TDI
2010 JSW DSG, 2013 JSW 02Q, 2004 Golf 02J, 2003 Jetta Ute 02J swap, 2003 Golf future 02J swap
I did test N75 in output tests, and it seems to pass the test. You can also hear the difference in exhaust between a mid-90s duty cycle and a 5-6% duty cycle. My vacuum hoses are all new, as is the brake booster grommet (old one was cracked).

I was reading up on using oven cleaner to clean the vanes, and I've read both good and bad things about that method.
 

mk1chris

Member
Joined
Sep 23, 2020
Location
durham uk
TDI
mk1 golf with pd130 swap ,mk5 ppd 170 bmn daily
ive had success with the mr muscle oven cleaner spraying in exhaust side and egr port on exhaust manifold , then using a large syringe on vac line to move the vanes
 

KrashDH

Veteran Member
Joined
Dec 22, 2013
Location
Washington
TDI
2002 Golf
I did test N75 in output tests, and it seems to pass the test. You can also hear the difference in exhaust between a mid-90s duty cycle and a 5-6% duty cycle. My vacuum hoses are all new, as is the brake booster grommet (old one was cracked).

I was reading up on using oven cleaner to clean the vanes, and I've read both good and bad things about that method.
ive had success with the mr muscle oven cleaner spraying in exhaust side and egr port on exhaust manifold , then using a large syringe on vac line to move the vanes
Do NOT use oven cleaner. It does not play well with cast aluminum. It's very porous and will get into the pores and dissolve/etc the aluminum. Not a good thing, can cause it to become weak and brittle
 

mk1chris

Member
Joined
Sep 23, 2020
Location
durham uk
TDI
mk1 golf with pd130 swap ,mk5 ppd 170 bmn daily
Do NOT use oven cleaner. It does not play well with cast aluminum. It's very porous and will get into the pores and dissolve/etc the aluminum. Not a good thing, can cause it to become weak and brittle
heard it a million times its done absolutly no harm to any of my cars
 

BobnOH

not-a-mechanic
Joined
May 29, 2004
Location
central Ohio
TDI
New Beetle 2003 manual
Yes, many folks have had success with oven cleaner. But I don't believe any shortcuts with turbochargers or injection pumps will give you longevity of repair. As we fix up our 15-20 year old cars, cost does become an issue and end of life may not be as much of a concern.
 

pkhoury

That guy with the goats
Joined
Nov 30, 2010
Location
Medina, TX
TDI
2010 JSW DSG, 2013 JSW 02Q, 2004 Golf 02J, 2003 Jetta Ute 02J swap, 2003 Golf future 02J swap
So I ended up deciding to do the oven cleaner route. No Mr. Muscle here. Even though it's produced by a major chemicals corp, I don't know if it's limited to EU/UK or not. Anyways, I used something with sodium hydroxide, and put some in both the EGR port and exhaust side of the turbo. The car is on ramps, so the back of the engine is leaning towards the ground.

That said, this is a relatively new turbo. With the limited room I had to check, there was practically NO shaft play side to side or in and out, which is a good thing. If this doesn't solve the trick, I'll probably remove the turbo from my mom's BEW for the time being and see if I can't get this one cleaned out (since that turbo is practically brand new).
 

wonneber

Top Post Dawg
Joined
Oct 12, 2011
Location
Monroe, NY, USA
TDI
2014 Jetta Sportwagen, 2014 Tiguan,2003 Jetta 261K Sold but not forgotten
I don't know if the VNT-17 has a clip holding the actuator linkage onto the turbo arm but if you can get it off you can move the arm full range to see if it's binding.
I've had luck getting it freer on my 03 followed by a run down the highway at 3K RPM (or so) for 20 minutes & back to heat it & blow out anything loose.
 

pkhoury

That guy with the goats
Joined
Nov 30, 2010
Location
Medina, TX
TDI
2010 JSW DSG, 2013 JSW 02Q, 2004 Golf 02J, 2003 Jetta Ute 02J swap, 2003 Golf future 02J swap
It's a little more difficult to do a highway run here at that, since I'm always up and downshifting (I live rural and our roads are 65-70mph, but curvy). I decided I'll just swap turbos with my mom's BEW (her turbo literally has like 7k miles on the clock), along with new intake and exhaust gaskets, and then I can see what needs to be done on the overboosting turbo. I'm hoping it's something as simple as dirty vanes or needing a new actuator.
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis (where it's safe)
TDI
There are just too many to list....
Has the car ever set an overboost DTC? Sounds to me like you are chasing a problem that is in the software, not the hardware, and it may not even be a "problem" at all if the ECU is happy. If you have an aggressive tune (Stage 4?), then you probably CAN'T run 90+ for very long?
 

pkhoury

That guy with the goats
Joined
Nov 30, 2010
Location
Medina, TX
TDI
2010 JSW DSG, 2013 JSW 02Q, 2004 Golf 02J, 2003 Jetta Ute 02J swap, 2003 Golf future 02J swap
Has the car ever set an overboost DTC? Sounds to me like you are chasing a problem that is in the software, not the hardware, and it may not even be a "problem" at all if the ECU is happy. If you have an aggressive tune (Stage 4?), then you probably CAN'T run 90+ for very long?
Yeah - all the time!

I do have an aggressive tune.

As for an update - it turns out my turbo has the EXACT same part number as a turbo I pulled from an ALH at the junkyard about 2 months ago. The car it came off of looked like it was modded by someone who didn't know what the hell they were doing, but the turbo was in really good shape. No shaft play, blades looked good, and VNT actuator moved freely. So, that turbo went into the BEW tonight (while I figure out how to get the exhaust portion off my old turbo.

Took the car for a test drive, and wow! All that power I forgot I ever had. And no limp mode/overboost DTCs, either. I did notice that boost was around 300mbar higher than requested (when I logged into a CSV through VCDS). But still, the car was more than responsive. Next I guess will be disassembling the old turbo further to clean the vanes, along with pictures, since we can now do that on this new forum software.
 

pkhoury

That guy with the goats
Joined
Nov 30, 2010
Location
Medina, TX
TDI
2010 JSW DSG, 2013 JSW 02Q, 2004 Golf 02J, 2003 Jetta Ute 02J swap, 2003 Golf future 02J swap
You could post pictures on the old software (I've posted hundreds). ;)
Smartass LOL.

Myturbodiesel had a video on cleaning the vanes. That aside, do you have any suggestions Brian on how to clean out the vanes, and first, how to remove the exhaust housing on the turbo? The bolts and actuator are already removed.
 

pkhoury

That guy with the goats
Joined
Nov 30, 2010
Location
Medina, TX
TDI
2010 JSW DSG, 2013 JSW 02Q, 2004 Golf 02J, 2003 Jetta Ute 02J swap, 2003 Golf future 02J swap
I don't clean turbochargers, sorry. If I take a turbo out, a replacement goes back in. I wouldn't even mess with one on one of my own cars.
Fair enough. I haven't figured out how to disassemble the turbo anyways, but the new one works great. No more overboosting and the car feels pretty normal. Even if I don't reuse it, it's still a learning tool taking it apart. Like I may (or may not) have mentioned, there's no in and out play on the shaft, and minimal up and down. What worries me are small nicks on the charged air side blades, probably when my boost pipe came off the turbo in the past (I ultimately got it figured out, so it stays put).
 

wonneber

Top Post Dawg
Joined
Oct 12, 2011
Location
Monroe, NY, USA
TDI
2014 Jetta Sportwagen, 2014 Tiguan,2003 Jetta 261K Sold but not forgotten
Myturbodiesel had a video on cleaning the vanes. That aside, do you have any suggestions Brian on how to clean out the vanes, and first, how to remove the exhaust housing on the turbo? The bolts and actuator are already removed.
I think the blue wrench is needed.
Oxygen & Acetylene. 😲
Heat the manifold to expand it a bit.
 

pkhoury

That guy with the goats
Joined
Nov 30, 2010
Location
Medina, TX
TDI
2010 JSW DSG, 2013 JSW 02Q, 2004 Golf 02J, 2003 Jetta Ute 02J swap, 2003 Golf future 02J swap
Ha, yet another upgrade/purchase. I didn't even think of trying my mapp gas torch, but if that fails, I think I can get a map+oxy torch from home depot. I have old hoses for oxy+acetylene, but the cost for new hoses/seals would set me back around $150. :-/
 
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