test N75 > VCDS > Measuring Blocks > Switch to basic Settings > "Greyed Out"

Arnaudov78

New member
Joined
Aug 30, 2017
Location
Gabrovo , Bulgaria
TDI
Golf mk4 ASZ 2002 / Golf mk4 AHF 1998
Hello everyone . I have ASZ engine with GT1749VA turbo and I need to replace his actuator, because the rod of actuator is very damaged by corrosion and can't move all the way up that cause over boost. So can I use this method ( basic setting on channel 11) to adjust the length of the rod of the new actuator? And how should it move? In lower position it's must hit the stoping screw, is that right? But how can I understand that the rod it's not too short? There no mark for maximum upper position of VNT arm, like the stoping screw for the lowest position?
 

DanG144

Top Post Dawg
Joined
Aug 2, 2007
Location
Chapin, South Carolina, USA
TDI
2005 A4 Jetta 5spd
Try setting the actuator so that it starts to move at about 4 or 5 psi (0.3 bar absolute pressure or so), and that should work for you. This requires a vacuum gauge.

It is hard to set an actuator with just VCDS, since the actuator rapidly has no vacuum, then full vacuum applied during the basic settings test.

You can set it by trial and error with VCDS. Log the data in measuring value block 3 (or have a friend watch it for you) as you drive. Then adjust the actuator so that you do not get over or underboost and at moderate constant load (when you have constant specified boost) your actual boost is near the the target boost. This can take a lot of trial and error.

But if you set it with a gauge to start moving at 0.3 bar absolute it should work fine.
 

Arnaudov78

New member
Joined
Aug 30, 2017
Location
Gabrovo , Bulgaria
TDI
Golf mk4 ASZ 2002 / Golf mk4 AHF 1998
Thanks you for responding. Unfortunately I don't have vacuum gauge for now and probably I'll try only with VCDS on 11 channel. I have a boost gauge (mechanical VDO) on my car, so it should show me what happens with the boost after the adjustment of the actuator. I think that when the actuator is mount on his stand, he should enforce a little compress at upper position over VNT arm and when the vacuum is applied by VCDS in basic setting test on the actuator, the rod should go all the way down right to stop screw so not hit him hard, just touch it. Am I right?


Sent from my iPhone using Tapatalk
 
Last edited:

DanG144

Top Post Dawg
Joined
Aug 2, 2007
Location
Chapin, South Carolina, USA
TDI
2005 A4 Jetta 5spd
It often hits the stop screw pretty hard. It may hit the stop screw by about 75% of full vacuum.

I would pull as hard a vacuum as I could with my breath, and ensure it does not move at all. If you initially set it so that it barely took up the slack with your breath, and then went about 2 turns further on the rod adjustment, it would be about right.

You should never adjust the stop screw.

Good luck.
 

Arnaudov78

New member
Joined
Aug 30, 2017
Location
Gabrovo , Bulgaria
TDI
Golf mk4 ASZ 2002 / Golf mk4 AHF 1998
Thank you for the advice. I planned to do this job today and I will report here what is happened.

I has never adjust the stop screw and I won't , it's are on the original position.
 

CRD4me

Veteran Member
Joined
Apr 15, 2014
Location
Canada
TDI
MB CRD & VW PD
This thread is amazing!
Thanks alot guys.
Would a faulty N75 actuator on a 2004 BEW would cause excessive smoke ?
I have a MIL on and a noticeable lack of power below 2500 rpm, but I dont see smoke in the back.
Symptoms started a feew days ago but MIL poped up today.
Engine serms to clatter a bit more also in the low RPM.
Thanks for any advices.
 

Arnaudov78

New member
Joined
Aug 30, 2017
Location
Gabrovo , Bulgaria
TDI
Golf mk4 ASZ 2002 / Golf mk4 AHF 1998
It's done . Thanks a lot again for your help . I has replace the actuator . The old one was totally blocked by the rust. And can't be moved even with hard force by hand. Actually, I have driven so far with completely immobile VNT. Now it's work pretty well and the boost is what it should be too. When I kick down the pedal the car is going to fly :) Best Regards.
 

CRD4me

Veteran Member
Joined
Apr 15, 2014
Location
Canada
TDI
MB CRD & VW PD
I think I have found my problem.
I plugged in VCDS but I couldn't come to a conclusion with the data I saw. Only thing for sure is that vcds was showing me a boost that was very low/absent (999 mbar) event when using some throttle at idle.
So I crawled under the car.
Removed the air duckings from turbo (in and out).
I then gently pushed down by hand the vane actuator rod and psshhtt the turbo significantly started blowing air and the actuator stayed into position and worked normaly.
For some reason the actuator needs a little help to reach the position.
I looked at the vaccum tube and it feels like there is some vaccum. How much? I dont know...

I came to 2 conclusions:

1 - insuficient vaccum (maybe check valve at the brake booster line??)

2 - Something inside the actuator is stuck making it difficult to move.

Turbo is KP39 BorgWarner
 

DanG144

Top Post Dawg
Joined
Aug 2, 2007
Location
Chapin, South Carolina, USA
TDI
2005 A4 Jetta 5spd
Check your vacuum at the check valve with the small take off in the large line between vacuum pump and brake booster, but measure it at the small take-off nipple. You should have about 20"hg vacuum at idle there.

Then check it at the vacuum port on the N75, again, you should have 20" at idle. Then check on the outlet line from the N75 to the turbo actuator during this test, it should vary between <3" to >18" hg during this test.
 

CRD4me

Veteran Member
Joined
Apr 15, 2014
Location
Canada
TDI
MB CRD & VW PD
DanG144,
Thank for the assistance.
When I disconnect the tube that goes to the turbo vane actuator at idle I get 20mmHg.
I'm not sure that I understand what configuration I should use to see that oscillation between 3 to 18 hg? Do you mean measuring the vaccum at N75 while performing an output test under basic settings in vcds at group 011?
 

DanG144

Top Post Dawg
Joined
Aug 2, 2007
Location
Chapin, South Carolina, USA
TDI
2005 A4 Jetta 5spd
Yes.
20" to the turbo vane actuator at idle is normal. It is positioning the turbo to give you rapid boost increase when you come off idle.
The 3 to 18 is really "from less than three to more than 18".

It sure sounds as if you have a sticky actuator. Probably full of rust.
 

CRD4me

Veteran Member
Joined
Apr 15, 2014
Location
Canada
TDI
MB CRD & VW PD
Thanks mate,
I haven't finish testing yet, but I'm expecting the same conclusion as yours.
The other issue I have is that I see oil leaks at the turbo outlet port and a little puddle of oil in the intercooler.
With all of this taken into account, I'm diving into a dilema. New turbo or just replace the actuator... car is 247,000 km now :\
 

DanG144

Top Post Dawg
Joined
Aug 2, 2007
Location
Chapin, South Carolina, USA
TDI
2005 A4 Jetta 5spd
When the actuator quits working, the oil mist build up is normal, if it is stuck on low boost. You have to clean it out when you fix the actuator, or it can flush into your cylinders and cause hydrolock.

When your turbo is at low speed, the oil slingers for the seals are not as effective. I will use more oil stuck in traffic for an hour than I use in 7,000 km, and nothing is wrong with my turbo.
 

CRD4me

Veteran Member
Joined
Apr 15, 2014
Location
Canada
TDI
MB CRD & VW PD
This makes a lot of sense.
Never thought of that TBH. I drive with no tune install, the car is pretty much stock except for a 6 speed gear box, cruise control install and a full MFA install. So yeah, my turbo should be fine for a couple more miles. Its unfortunate that cartridges/rebuild kit for the stock turbo are not available :\
 

CRD4me

Veteran Member
Joined
Apr 15, 2014
Location
Canada
TDI
MB CRD & VW PD
test N75 > VCDS > Measuring Blocks > Switch to basic Settings > "Greyed Out"

Ok... more diagnostics:
I did the vaccum test with vcds on basic settings ON.
Controller rises the engine speed at 1407 rpm. Vaccum rises at 22 mmHg. Every 5 sec, as the N75 open and closes from 9% to 90%, this makes my vaccum to fluctuate, literaly, from 0 mmHg to 22mmHg. Am I way off range from the 3 to 18mmHg?
I inspected this check valve :

With a clean tube I tried to activate the check valve with my mouth, but I don't feel any resistance.

-what's the best way to inspect this check valve?
-would a faulty check valve induce a poor performance of the vane actuator ?

Thanks guys.
 

CRD4me

Veteran Member
Joined
Apr 15, 2014
Location
Canada
TDI
MB CRD & VW PD
Anybody ?
Are the numbers I'm seeing when doing the test are in normal range (from 0 to 22 and back at 0...etc...)
Thanks for the assistance.
 

Fix_Until_Broke

Top Post Dawg
Joined
Aug 8, 2004
Location
Menomonee Falls, Wisconsin, USA
TDI
03 Jetta, 03 TT TDI
Is there a VCDS measurement of the actuator position sensor on the BRM's?

Seems like you should be able to cycle the actuator and read the actuator position sensor to see if you have sticky vanes or not? I looked all over in measurement blocks, but didn't see anything that looked even kind of close.

Trying to help a co-worker on his 06 beetle TDI.
 

DanG144

Top Post Dawg
Joined
Aug 2, 2007
Location
Chapin, South Carolina, USA
TDI
2005 A4 Jetta 5spd
There is one. Look at block 43, field 1 is N75 duty cycle, field 2 is turbo actuator vane position. This is not documented by VW (anywhere I can find). it was documented by myself and Dan Schein in a very handy expanded label file.

I cannot guarantee this works on all PD engines, but it does on most.
 

BobnOH

not-a-mechanic
Joined
May 29, 2004
Location
central Ohio
TDI
New Beetle 2003 manual

Matt-98AHU

Loose Nut Behind the Wheel Vendor
Joined
Apr 23, 2006
Location
Gresham, OR
TDI
2001 Golf TDI, 2005 Passat wagon, 2004 Touareg V10.
I realize this is an old post, but quick question, when talking about vacuum, some used units of inhg, some mmhg, which is correct?
Depends on what your vacuum gauge is displaying. Both are fine so long as you know how to convert between the two.
 
Top