Turbo question

Instigatr

Member
Joined
Sep 4, 2016
Location
NE WA State
TDI
03 Golf 2 door MTM
So I have been having an overboost and boost creep problem on the 03 Golf I inherited from my brother. Thankfully he did put a boost gage on it, as at one point i was hearing some funny noises from the engine. Looked at the boost gage and it was pegged at over 30 psi. Took my foot out of the throttle immediately, boost dropped immediately, and then started playing with boost to get a better feel for what's happening. When the car is cold, it will overboost bad. As the engine warms up the overboost problem gets better. Once fully warmed up, then the boost spikes to 20 psi and then drops to 18 psi. If I keep my foot in it, pressure starts climbing, somewhat gradual. Don't know how high it will go, honestly don't want to find out. I have found some paperwork possibly for the upgraded turbo my brother put on, but it lists it as an upgrade for a BEW engine. It is a Garret turbo, GT1749V. Garrett part number 778445-5002S. I have not been able to determine if its possible to take the electronic actuator off and bolt the original ALH one on. Anyway, does anyone have any ideas for me to check? First thing comes to mind is moisture in the turbo lines somewhere, but how if so? And since it gets better as it warms up, it kind of leads me away from the moisture problem.
I am learning here, just difficult to make my Toyota brain transfer over to a VW brain 😀
Aaron
 

Rrusse11

Veteran Member
Joined
Jan 23, 2014
Location
PA Deutsch Country
TDI
2002 Golf, 5spd; 05 Jeep CRD
Firstly why the hell are you hitting full throttle when the motor's cold? It's a diesel! Before you start beating on it, at least let it get to operating temps. Sell it before you kill it, and go buy a Toyota. Sorry to be so harsh, but a change in driving habits/usage are in order. The TDI is not a grocery getter or good for short hops around town; long commutes,
highway miles, you can't beat 'em. Adapt to what they are good at and they'll go 500k miles with a certain modicum of care and respect.
 

Nero Morg

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Oct 19, 2017
Location
OR
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2003 Jetta wagon, 2001 Jetta TDI, 2014 Passat TDI
Woah slow down there R man.

So judging by your listed vehicles, I assume it's the one you inherited and don't know what mods have been done to it, right?

It doesn't have an electric actuator, it's strictly vacuum. It's not uncommon that the actuator will get sticky as it gets older due to wear and carbon buildup. If you have a mityvac, hook it up to the turbo actuator and apply a vacuum. Actuator should start moving about 3-5inhg and full stop at 16-18inhg. Start there.


Also, rule of thumb it's better for the turbo at least if the exhaust Temps reach around 200f before hammering on it, but optimal if you're at least above 144f coolant temp. The dash gauge is a dummy gauge, you'll have to monitor coolant Temps with a scangauge or other obd2 scanner.
 

Vince Waldon

Top Post Dawg
Joined
Apr 25, 2009
Location
Edmonton AB Canada
TDI
2001 ALH Jetta, 2005 BEW Wagon
Yup, vacuum actuator but if it's for a BEW it also has an electronic position sensor, so it has both a vacuum hose and some wiring, which can be a bit confusing.

You'll get lots of opinions here on how to approach this pretty common problem, all worth exactly what you're paying for them. :)

My own suggestion: my sig has a link for a great step-by-step on tracking down low-power/boost issues, and I'd recommend step-by-step, as there can be multiple causes and it can be expensive to shotgun.
 
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Tdijarhead

Top Post Dawg
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Nov 10, 2013
Location
Lawrenceville PA
TDI
2003 TDI Jetta Daughters Car, 2001 TDI Beetle, Daughters car, 2005 Golf TDI Mine, all 5 spds
It sounds like your brother set the car up with a bigger turbo and often a bigger turbo goes hand in hand with a tune, a more robust clutch and bigger nozzles/injectors. If your turbo has a “smart actuator “ on it, it probably has just the vacuum line hooked to it and no wiring connected. Which though I’ve never done that I understand you can do with an ALH.

I think the first thing to do is figure out what he did (mods) with the car. Would there be any receipts for any of the work done anywhere? Who did he have do the work or did he do it himself?
 

BobnOH

not-a-mechanic
Joined
May 29, 2004
Location
central Ohio
TDI
New Beetle 2003 manual
Rule out the simple stuff before going after one of the most expensive parts on the car. Often these issues are caused by loose piping, engine controls, etc.
 

PakProtector

Veteran Member
Joined
Jan 5, 2014
Location
AnnArbor, MI
TDI
Mk.4 and the Cummins-es
That turbo looks like a VNT17, as judged by its compressor 36mm inducer and 38mm turbine exducer...

As such, on an ALH with stock injectors, and an OE tune it should not be suffering from boost creep. It should also be less sensitive to getting cruddy vs the earlier incarnations of the VNT mechanisms.
cheers,
Douglas
 

Instigatr

Member
Joined
Sep 4, 2016
Location
NE WA State
TDI
03 Golf 2 door MTM
Thanks guys. Got blown away by the butt chewing. I don't drop the hammer on it until the engine is pretty close to normal. Well sometimes I have to as i pull out onto a 60 mph why after driving 1 1/2 miles. But especially when its 40 degrees outside or colder i will start the engine and let it idle for at least 10 minutes while I finish getting ready for work. I know it has a tune, as when I connect vcds it lists rocketchip on the main screen. I found some paperwork from when he bought it, used of course. It lists having PP520 injectors and a Rocketchip stage 2. Also says something about a "Boost valve". Also had a stage 2/3 clutch installed by "Zahntech" at about 113k, has 176k on it now.
I don't remember seeing anything electrical on the turbo, just the standard vacuum actuator.
The bad : "cold air intake" I'm sure installed by my brother. It will be getting put back to stock in the spring. Good thing for parts cars....
I will be checking the actuator for proper operation it sounds like as soon as I get a chance. For now i am being careful to monitor the boost level.
As my parts car is an automatic, has 300k on it dunno how the 01m lasted that long, I have been starting to research the possibility of putting that injection pump on. Not sure yet. Will have to decide fairly soon as my car is almost due for its timing belt.
Thanks again all.
 

Rrusse11

Veteran Member
Joined
Jan 23, 2014
Location
PA Deutsch Country
TDI
2002 Golf, 5spd; 05 Jeep CRD
Instigatr,
My apologies for being a COC, (cranky old curmudgeon). It was uncalled for, put it down to general rage at the geopolitical situation. You've got the right approach, figure out what you got, do the TB asap and get rid of the intake.
 

Instigatr

Member
Joined
Sep 4, 2016
Location
NE WA State
TDI
03 Golf 2 door MTM
Rrusse11 - no worries. It did surprise me but no hard feelings. Looking back and rereading my original post, I did not word it very well. I can see exactly why your thoughts went that way. I bear the responsibility of what I type.
At the risk of getting off topic, our geopolitical situation is not good and not looking to get better anytime soon.
Aaron
 
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turbocharged798

Veteran Member
Joined
May 21, 2009
Location
Ellenville, NY
TDI
99.5 black ALH Jetta;09 Gasser Jetta
A GT1749V is the factory VNT15 so it looks like the stock turbo to me.

I would say that the above posters are correct, the vacuum actuator is sticky. You can push down with your thumb and it should move somewhat easily. If you have a mityvac or similar you can hook it up the the vaccum actuator and watch it cycle. It should begin to move around 3in/hg and hit full stop around 18 or so. Its possible that the VNT ring inside the turbo is stuck with soot and rust as well.
 

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....
Overboosting is usually going to be a stuck VNT actuator in the turbo. It happens if the car gets driven too easy to often, or for extended period of idle time, especially when cold. You shouldn't let the car sit and idle after a cold start. Start it up, and drive away, and trying to keep the RPMs above 2500 but below 3000 with low load (afterglow kicks on below 2500, so if you can keep the RPM from swing back and forth past 2500 your glow system will last longer, although the 2002+ cars are not nearly as bad for this with the "smart" relay).

Sometimes you can clean/free up the VNT, sometimes the wear in the ring inside is just too great and the turbo will need to be replaced.

FWIW, the ECU is not concerned, because if it was it would have already put the engine in limp mode, and set an overboost DTC. If it has not done that, and it seems to run OK, I am not sure how much I'd worry about it because it is possible the ECU has been reflashed and is requesting more boost than normal (some tunes do that, and some are better than others).

You may also have a sticky N75, that isn't able to vent the vacuum fast enough. This happens from either the vacuum vent line left loose from the air cleaner (so unfiltered air is constantly being pulled through the N75), or the old turbo's VNT actuator rusted out, which was why it was replaced, and the little bits of debris have been sucked up into the N75.

My advice is:

ask if the ECU has been modded for power, and if so by whom

ask why the turbo was replaced

take the N75 off and try blowing through it while it is off and on (just 12v, jumper wires will work fine).
 

Rapid Transit

Well-known member
Joined
Oct 2, 2010
Location
SF Bay Area
TDI
03 4dr Golf GLS
Oilhammer - you are an asset to this community with your wealth of knowledge, ability to convey and willingness to share.
Thank you
 

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....
Thank you. And I meant to say to the OP, I am sorry for the loss of your brother (I have lost one, too). And I realize you may not be able to answer the question of the state of tune and the turbo replacement reason.
 

Instigatr

Member
Joined
Sep 4, 2016
Location
NE WA State
TDI
03 Golf 2 door MTM
Thank you oilhammer. The worst part about it is he was the second brother we have lost. Both due to cancer. So yes, cancer sucks.
Anyway, thank you all for your help. I have read the diagnosing limp mode post multiple times, but for some reason I never applied the thought to this problem. Maybe because it has not gone into limp mode (yet at least). It's still interesting to me that it gets better as it seems to get warmer under the hood. Maybe there is a little bit of moisture in the actuator and it has rusted a little bit. I will be finding it out and will update what the problem turns out to be.
 

Gothmolly

Veteran Member
Joined
Feb 3, 2005
Location
Providence, RI
TDI
2002 Golf
Firstly why the hell are you hitting full throttle when the motor's cold? It's a diesel! Before you start beating on it, at least let it get to operating temps. Sell it before you kill it, and go buy a Toyota. Sorry to be so harsh, but a change in driving habits/usage are in order. The TDI is not a grocery getter or good for short hops around town; long commutes,
highway miles, you can't beat 'em. Adapt to what they are good at and they'll go 500k miles with a certain modicum of care and respect.
Lighten up, Francis.
 

Instigatr

Member
Joined
Sep 4, 2016
Location
NE WA State
TDI
03 Golf 2 door MTM


Trying to post a picture, hopefully just a thumbnail..., Anyway, anyone have any idea what this is? I suspect it's a "boost valve" but not sure. The bigger line is going into the intake manifold, the black hose coming out at 90 degrees T's into the turbo actuator vacuum line between it and the N75 valve. Cleaned it and tried backing off the adjustment thinking it would lower the max boost. Didn't seem to be making a difference.
Another thing that has me curious is why it's not setting an overboost code. Is it possible that the computer has been programmed to ignore overboost? My brother was a very talented computer programmer.....
Edit: looks like the picture worked. The picture is probably to big, but the part I am referring to is on the right side of the picture. Tried to get a overall picture of how it is connected.
Aaron
 

Instigatr

Member
Joined
Sep 4, 2016
Location
NE WA State
TDI
03 Golf 2 door MTM


Here is a picture of the part not installed.

Edit : sorry OilHammer, I did check some of what you suggested so far. Actuator is moving nicely, appears to start moving between 3 and 5 inches of vacuum, stops at around 18". It does also hold vacuum. Swapped the N75 valve withal brand new one i had laying around. Hopefully I will get a chance on Thursday to check requested boost vs actual. I work in retail at a well know appliance store that recently went through bankruptcy. Therefore my next week or two will probably be busy.
Thanks again.
Aaron
 
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Nero Morg

Veteran Member
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Oct 19, 2017
Location
OR
TDI
2003 Jetta wagon, 2001 Jetta TDI, 2014 Passat TDI
That definitely looks like a boost valve. Honestly I'd stop using it. They're more of a bandaid device for over boosting, but since these have a variable nozzle turbo, they don't quite work right. Turbo actuator should be plumbed straight to n75 with no tees in it. If you do take it off be sure to plug the intake port or you'll get a nice boost leak :)
 

Instigatr

Member
Joined
Sep 4, 2016
Location
NE WA State
TDI
03 Golf 2 door MTM
@ Hero Morgan - when I was looking at it last night, I was wondering why it would even be installed. As I see it, a properly functioning N75 valve makes the "boost valve" totally unnecessary. It will be removed shortly. I did notice as part of diagnosing the system, it is not building the correct vacuum very quickly. If I remember correctly, it went to about 20" of vacuum right away, then as i messed with the vacuum lines I was able to get it up to about 25". But then I couldn't duplicate it again. Anyway, I don't trust the old vacuum lines now so I am going to replace all.

@ BobnOH - I am glad you asked that as I totally missed that part of the test when I was reading it last night. I will check and get back to you.

One question i have, and I can't seem to find the answer in Bentley, just to make sure that I am understanding the system correctly, should more vacuum to the actuator increase boost, or should more vacuum decrease boost? Based on the boost valve installation, and if i am understanding what it is supposed to be doing, less vacuum should be less boost, correct? (This of course is assuming that the boost valve is even installed correctly)
Thanks again guys!
 

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....
Those add on boost valves were a band-aid early on for poorly done boost mapping by some tuners, as well as a bit of a "safety' override for some really aggressive setups. We know more now, and we know better, and they really are not necessary. The idea was, being a simple mechanical device, that they would react faster than the ECU could, given the ECU needed to "see" the level of boost via the MAP, react to it via changing the duty cycle of the N75, then allowing the VNT's vacuum to bleed off thus bringing the boost back down, where it was once again verified via the MAP signal.

The earlier Bosch EDC15 ECUs were slower, and these were something that was being used on the early VNT-equipped cars with these slower ECUs. So for North America, we are just talking 1998 and 1999 ALHs. 1998s were just one model, the New Beetle, and 1999 was just about 2/3 of one model year as the early '99 Golfs and Jettas were still the A3 platform.

I think the use of these carried over from habit and limited knowledge for a couple more years, as I know when my coworker bought his 2001 Golf brand new they were still often employed, but more "recommended" and not "required".

If it were my car, I would remove it and throw it in the trash, make sure any holes are plugged up, and put the vacuum system (especially as it related to VNT control) back to stock. Let the ECU do its job. If it can't, it will tell you, as it will set an overboost DTC, and this will be reflected in the freeze frame data for when the DTC set, and you can typically graph it (which is why I will ask once again if you have driven the car and watched the Actual vs. Requested boost level... you may be chasing a problem that doesn't exist).

It is normal for boost to spike up when you first lay into the go pedal. If power adding software has been placed in the ECU, this spike can be higher. However, it generally is not a problem. Since we still have no idea what all has been done to the car, this can be a bit of guesswork. I can already tell that stuff has been done to it (aside from the boost valve) as it has one of those aluminum air inlet tubes and an EGR delete pipe on it. Your brother may have simply been "ordering off the menu" of one (or more) of the popular vendors that sell bolt on "stuff" to make the car go faster, even if it didn't really do exactly all what was intended.

A 100% stock ALH with a mild (commonly called "stage 1") tune is a very good running setup. Peppy, reliable, efficient, not smoky, and has great driveability. Sometimes people go after modifying things before they really have a good handle one what they are after and what works best for what their driving entails. In cases like yours (and I have been there, as I have purchased SO MANY used cars just like yours) I often find it best to get it back to stock or as close to it as reasonable to get a better handle on what I am working with.
 

Instigatr

Member
Joined
Sep 4, 2016
Location
NE WA State
TDI
03 Golf 2 door MTM
Thought I replied to this the other day. Apparently not....
Anyway wanted to give an update where am at with the car. Hit a deer on the way home so it is now at the body shop. When I get it back, I will go back to proper diagnosis.
I wanted to thank OilHammer for the well thought plan. It is so nice to have someone with such a wealth of knowledge helping us out. I have 20 years of professional Toyota repair experience and very quickly i am learning that don't help me much. At least I understand the lingo for the most part!
Thanks again all
Aaron
 

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....
You are welcome. I am a bit of a closet Toyota guy, too. Wrenched on lots and lots of them over the years. Don't have any now, though. I even had a couple diesel Toyotas :) . And our shop is often balls deep in some wallet burning Prius repair or the constant sudden rash of evaporator cores on the newer stuff which I find really strange. I am not a fan of the newer Toyota products as compared to the older ones.
 
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