VNT 17 carbon buildup after 10k?

Ryder1032

Well-known member
Joined
Feb 13, 2021
Location
Hagersville, ON
TDI
2004 Golf BEW
Hey guys. Really in need of some help and advice because I don’t know where else to look. So I’ve been experiencing the overboost code for my 2004 Golf TDI (BEW). The previous owner had put on a VNT17 due to the factory turbo failing at 266k. I previously got overboost codes, ended up popping the timing belt at 318k and having to do a head swap, so I installed a kerma smart actuator and pulled the turbo and cleaned it out and found the carbon buildup jammed up the veins in the turbo. Cleaned out the turbo and installed with new kerma smart actuator (bench tested it and does open and close at right psi level before installation), deleted the EGR while the head was out and everything was running great and no problems at all for the past 10k until now. I’ve recently started to get the code again throwing me into limp mode making it terrible to drive. I’ve checked all vacuum lines, all plumbing for boost leaks, tested the n75 with VAGCOM and it is working proper, tested the turbo actuator and it is still opening and closing at the right level and the rod is still moving on the actuator and the turbo. Looking at the rod coming out of the turbo you can already see large carbon buildup coming out from around the hole. I’m planning on trying to get some oven cleaner through the Egr opening and into the turbo as I read it’s an east way to clean it without removing but if this doesn’t seem to work I’ll be pulling the turbo in the next few days to inspect it.

I’m curious to know, how could the turbo get so built up with carbon over just 10k to cause the code to come up again? Is there anything I should look for in the injectors maybe fueling too much causing carbon buildup? The injectors were from the head I bought in the head swap with only 272k on it whereas my originals had 318 when the timing belt went. (Injectors were cleaned and resealed during head swap). Any help at all is appreciated. I just don’t understand how the code could come back after 10k and the turbo being properly cleaned and reinstalled.
 

Mpaw

Veteran Member
Joined
Aug 21, 2018
Location
Europe
TDI
Caddy 2005 1,9 105 ps; Polo 2015 90PS Bluemotion, T5 2.5 5cyl
The only thing similar I've experienced was to do with the EGR, but you deleted it...
 

Mongler98

Top Post Dawg
Joined
Mar 23, 2011
Location
COLORADO (SE of Denver)
TDI
98 Jetta TDI AHU 1.9L (944 TDI swap in progress) I moved so now i got nothing but an AHU in a garage on a pallet.
2 things.
Forget oven cleaner. It damages the aluminum alloy turbo impeller. Some do it but its not worth the shortcut vs cost imo.
Dont drive like grandma. Get it nice and warm and go for a full revs drive though the canyon or backroads.
Heat is #1 at burning if off.

If you do oven cleaner. Remove the turbo hot side enough that it does not get much if any spray /foam on the aluminum bits and make sure you flush it out asap.

Imo it's worth pulling the turbo off to male sure it's not wearing the ring / actuator arm
You have a stock tune? If so you should get a tune for the turbo. Will help with soot and smoke.
 

Ryder1032

Well-known member
Joined
Feb 13, 2021
Location
Hagersville, ON
TDI
2004 Golf BEW
2 things.
Forget oven cleaner. It damages the aluminum alloy turbo impeller. Some do it but its not worth the shortcut vs cost imo.
Dont drive like grandma. Get it nice and warm and go for a full revs drive though the canyon or backroads.
Heat is #1 at burning if off.

If you do oven cleaner. Remove the turbo hot side enough that it does not get much if any spray /foam on the aluminum bits and make sure you flush it out asap.

Imo it's worth pulling the turbo off to male sure it's not wearing the ring / actuator arm
You have a stock tune? If so you should get a tune for the turbo. Will help with soot and smoke.
Thanks for the advice with the oven cleaner. I’ll definitely stay away from that then, I planned on pulling the turbo but just recently heard of it helping so thought I’d try it.
I’m always shifting at 32-3400rpm sometimes higher for city driving and much harder for highway driving.
No tune on the car but planned on getting a stage 2 Malone literally 3 days before the code came back again and will be going to get it as soon as this is resolved.

Forgot to mention as well that the car does have a straight pipe.
 

turbocharged798

Veteran Member
Joined
May 21, 2009
Location
Ellenville, NY
TDI
99.5 black ALH Jetta;09 Gasser Jetta
2 things.
Forget oven cleaner. It damages the aluminum alloy turbo impeller. Some do it but its not worth the shortcut vs cost imo.
Dont drive like grandma. Get it nice and warm and go for a full revs drive though the canyon or backroads.
Heat is #1 at burning if off.

If you do oven cleaner. Remove the turbo hot side enough that it does not get much if any spray /foam on the aluminum bits and make sure you flush it out asap.

Imo it's worth pulling the turbo off to male sure it's not wearing the ring / actuator arm
You have a stock tune? If so you should get a tune for the turbo. Will help with soot and smoke.
There is absolutely no aluminum on the hot side of the turbo. The hot side impeller is made from Inconel , oven cleaner ain't going to do squat to that.
 

Mongler98

Top Post Dawg
Joined
Mar 23, 2011
Location
COLORADO (SE of Denver)
TDI
98 Jetta TDI AHU 1.9L (944 TDI swap in progress) I moved so now i got nothing but an AHU in a garage on a pallet.
There is absolutely no aluminum on the hot side of the turbo. The hot side impeller is made from Inconel , oven cleaner ain't going to do squat to that.
Oh relay!
Thats good to know.
In that case Oven cleaner is #1 choice as it's not difficult to apply.
 

Nevada_TDI

Top Post Dawg
Joined
Aug 17, 2008
Location
Reno, sort of...
TDI
2001 Jetta TDI
Make sure the oven cleaner is all dissolved; I have heard stories about the oven cleaner using a flammable gas for the propellant
and flame up.
OBTW, you need to run your engine harder to prevent clogging in the control ring. Second and third gears are good as long as you are not running on a public road.
 

fatmobile

Veteran Member
Joined
Jul 16, 2019
Location
north iowa
TDI
an ALH M-TDI in a MK2, a 2000 Jetta, 2003 wagon
If you take it apart again.
Clean the vanes and spray some dry moly on the vanes and exhaust moving parts.
Do you have an EGT gauge?
Getting the temps up will help burn the carbon off.
I've heard 1200F is safe.
 

Ryder1032

Well-known member
Joined
Feb 13, 2021
Location
Hagersville, ON
TDI
2004 Golf BEW
What do you all reccomend for average rpms? I’m in Ontario, im usually in the city averaging from 40-70km and I try and keep the car around 26-2900rpm cruise in second or third shifting at 3200-3400rpm. Highway driving shifting around 38-4200 sometimes higher to get up to speed and a little more speed cruising around 32-3400rpm.

As of about an hour ago I just got home with another VNT17 I just found on Facebook for $60 cad used some guy got in a random part lot for a car he didn’t have. Going to be taking it apart and looking it over at work tomorrow.
 

DivineChaos

Top Post Dawg
Joined
Jul 27, 2019
Location
Minnesota
TDI
mk6 jetta sportwagen tdi
Once the car warms up I drive it fairly hard and let the turbo spool up and pull hard, I don’t ever grandma drive the car haha.
Strange that they sooted up and stuck. Maybe it was too tight. The vane lever on my oe turbo move easy
 

gforce1108

Top Post Dawg
Joined
Aug 2, 2006
Location
Newburgh, NY
TDI
04 Jetta GLS BEW, 14 Audi A7 V6 TDI, 13 Porsche Cayenne V6 TDI
My 04 (17/22) would soot up and get sticky in the winter because I was running snows and couldn't run it hard enough. I would hook up the trailer with a ATV/snowmobile, etc. and take a good romp up the local highway incline. Freed it right up! I couldn't get enough heat in it otherwise.
 

fatmobile

Veteran Member
Joined
Jul 16, 2019
Location
north iowa
TDI
an ALH M-TDI in a MK2, a 2000 Jetta, 2003 wagon
I don't think large carbon buildup from the rod coming from the turbo is normal.
Does it juggle?
Sit in the hole loose?
 

Ryder1032

Well-known member
Joined
Feb 13, 2021
Location
Hagersville, ON
TDI
2004 Golf BEW
My 04 (17/22) would soot up and get sticky in the winter because I was running snows and couldn't run it hard enough. I would hook up the trailer with a ATV/snowmobile, etc. and take a good romp up the local highway incline. Freed it right up! I couldn't get enough heat in it otherwise.
Thats what I was hoping would fix it. I tried doing hard pulls and every single time, as soon as the needle hits 90km/h on the dash in 3rd gear around 34-3800rpm the car will overboost and every single time at the same speed. I cannot go faster than 90km/h pulling or the code comes up. Even doing that, cycling the ignition, and doing it again and again did nothing at all. I’m gonna try and get some oven cleaner in it I think and see if that’ll help break it free and then the pulls to finish it off and free it up.
 

Zak99b5

Veteran Member
Joined
Apr 30, 2021
Location
Albany NY
TDI
2003 Jetta TDI
. I’m gonna try and get some oven cleaner in it I think and see if that’ll help break it free and then the pulls to finish it off and free it up.
If you're going to pull it anyway, I'd skip the oven cleaner with it on the car.
 
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