ALH Turbo VNT actuator doesn't move until 8"HG. Is this ok?
- Thread starter 777funk
- Start date
Rrusse11
Veteran Member
Auto or manual? Mileage? How's the car run? Stock turbo? Got VCDS? How long have you owned it?
It probably won't hurt anything, but you might be boosting a little late,
and potentially over-boosting. LOTS more details needed for a better
analysis.
It probably won't hurt anything, but you might be boosting a little late,
and potentially over-boosting. LOTS more details needed for a better
analysis.
BobnOH
not-a-mechanic
Spec on open is 3.5 to 5.0 "/Hg.
maxmoo
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....and some of our vacuum gauges aren't all that accurate.
sisyphus
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I seem to recall I had one that wouldn't open until 5, but I couldn't seem to get it to do anything else. Car ran for about 300K. I still have that motor, it's on a stand under the stairwell waiting for a going over.
BobnOH
not-a-mechanic
Does anyone know which end of the vacuum range is open and which is closed?
I know the car sits with the vanes open and when you fire it up it moves to closed.
This could indicate that the vanes don't fully open cause it never gets down to 5 "/Hg.
For all the reading I do here, you'd think I would know, but I don't know if any of this is correct.
I know the car sits with the vanes open and when you fire it up it moves to closed.
This could indicate that the vanes don't fully open cause it never gets down to 5 "/Hg.
For all the reading I do here, you'd think I would know, but I don't know if any of this is correct.
Nevada_TDI
Top Post Dawg
I suggest running a scan using VCDS to see your turbo is acting correctly or not; I also suggest you check the amount of vacuum coming out of the N75 valve at WOT. In theory your actuator arm is a bit "long", but you don't mention if your ECU is tuned or not.
BobnOH
not-a-mechanic
^^ Like that approach ^^
Nevada_TDI
Top Post Dawg
Which end of the vacuum range is open or closed? Zero inches of vacuum, vanes are open, full vacuum, vanes are closed--relatively speaking. So, no vacuum, no boost, lots of vacuum, lots of boost. As far as vanes fully opening or closing due to vacuum while engine is running, the N75 valve takes care of that. But, you still need a scan to see what the N75 valve is doing.
cfa5
Veteran Member
Since you asked if it would hurt your car, My suggestion:
adjust it to start moving at 4-5 and hit the stop at 17.5-18
adjust it to start moving at 4-5 and hit the stop at 17.5-18
Rrusse11
Veteran Member
Opening late, might be closing late as well at 20. Adjust to open 3-5,
set stop to 16. Actuator moving smoothly through the full range?
On & off? Vanes clean?
Yes, overboost codes and limp mode if I drivemore than a few minutes. It's basically a 40hp car due to it detuning itself.
Manual and stock to my knowledge. 99.9% sure on that.
The actuator is smooth and moves about 3/4" going by feel while MityVacing it.
Manual and stock to my knowledge. 99.9% sure on that.
The actuator is smooth and moves about 3/4" going by feel while MityVacing it.
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BobnOH
not-a-mechanic
Adjust it to spec.
Couple notes:
I never could make sense of the "over" or "under" the couple times I had boost codes.
There is only 1 adjustment, the book says 3.5 to 5.0 "/Hg. The high number (20?) is a good check, but you cannot set both.
Couple notes:
I never could make sense of the "over" or "under" the couple times I had boost codes.
There is only 1 adjustment, the book says 3.5 to 5.0 "/Hg. The high number (20?) is a good check, but you cannot set both.
wonneber
Top Post Dawg
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Did you replace or adjust anything before this started?
There's a VW bulletin saying the turbo actuator can rust internally causing it to stick.
I would take it off and check it. Turn it over and shake it to see if rust falls out.
Also check it with a vacuum pump if it holds vacuum and what vacuum it moves at.
While its out move the arm on the turbo the actuator connects to the full range.
It should move freely.
You should be able to put some pressure on it to make sure it's going the full range.
Cycle it back & forth for several minutes. Some have indicated this helps free some sticky spots if it because of carbon.
If the 'ring' or small vanes inside (not the spinning vanes) are warped this would not be cleared.
I found the clip on the arm easy to got off and harder to get on, loosing a few clips when they flew.
I finally tied some thread to the clip to make it easier to find.
Nevada_TDI
Top Post Dawg
777funk, you mention the vacuum numbers, and let me see if I can help explain...
With your actuator arm effectively being too long, the ECU is going to keep sending vacuum to the N75 valve in order to get the turbo to spool; therein lies the problem: the turbo is going to go into over boost as the N75 will most likely be at the maximum yet unable to bleed off the vacuum fast enough. In the ALH-TDI's the N75% is backwards to normal thinking, ie. If the N75% is reading high (90%+) it is trying to bleed off the vacuum and get the turbo boosting back under control, and if the N75% is low (30-40%) it is asking for more boost to be created. I have re-read this thread and I don't see any VCDS scan numbers that have been collected.
With your actuator arm effectively being too long, the ECU is going to keep sending vacuum to the N75 valve in order to get the turbo to spool; therein lies the problem: the turbo is going to go into over boost as the N75 will most likely be at the maximum yet unable to bleed off the vacuum fast enough. In the ALH-TDI's the N75% is backwards to normal thinking, ie. If the N75% is reading high (90%+) it is trying to bleed off the vacuum and get the turbo boosting back under control, and if the N75% is low (30-40%) it is asking for more boost to be created. I have re-read this thread and I don't see any VCDS scan numbers that have been collected.
I watched MAP while revving and it seemed to track in VAGCOM but I don't have the full version to do a graph while driving.
Interestingly, I accidentally snapped the brittle nipple on the N75 while checking vacuum supply. Bummer. But I think it may run better now. I still hear turbo whistle and have more power than in limp. Really it's almost as much as normal. Until the new N75 comes, this is better than it was.
Interestingly, I accidentally snapped the brittle nipple on the N75 while checking vacuum supply. Bummer. But I think it may run better now. I still hear turbo whistle and have more power than in limp. Really it's almost as much as normal. Until the new N75 comes, this is better than it was.
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wonneber
Top Post Dawg
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- Monroe, NY, USA
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- 2014 Jetta Sportwagon,2003 Jetta 261K Sold but not forgotten
Without the N75 hose to the turbo there's no vacuum to the turbo and no boost.
Car should show low power.
If it still has power I would think the actuator arm is not fully closed.
Car should show low power.
If it still has power I would think the actuator arm is not fully closed.
wonneber
Top Post Dawg
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- 2014 Jetta Sportwagon,2003 Jetta 261K Sold but not forgotten
Start tracing the vacuum loss backwards from the line to the turbo back.
Is vacuum getting to the N75 valve?
If not is it getting to the vacuum check valve?
If not is it getting to the side port of the valve just off of the vacuum pump?
Just like testing electrical but w/o the sparks.
Nevada_TDI
Top Post Dawg
You mention "pulled vacuum", did you do this with a hand pump? I would start at the vacuum nipple on the brake booster inlet and make sure at idle I had at least 22" of vacuum at idle. If you don't have at least 22" there, you may have much less as you go down the line towards the passenger side; going towards the passenger side there are three more places to potentially lose vacuum due to the solenoids aging. In my vehicle the only things I have that runs off of vacuum are the N75 and the brake booster as everything else has been deleted.
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AndyBees
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I believe how it all works and answers to these same questions is in the other Thread that the OP has going on this same topic.
I think my new (non OEM off ebay) N75 was bad. I had another thread to help me understand its function.
I have multiple problems though. I believe the old N75 worked fine until the nipple cracked.
Based on the problem that I started the thread with and the feedback here, I believe my actuator needs to be lengthened. I'm completely unplugged from vacuum and now it no longer goes into Overboost limp, but I don't get boost until 2100 RPMS. I'm thinking I have the VNT nozzles open to a spot that acts almost like a waste gate turbo (laggy). BUT I'm glad to have that. Limp means I have a non turbo dose of fuel. It's horrible. I can't keep the car at 70 on the interstate when in limp.
When it gets warmer out AND when I have time, I'm pulling the intake, and turbo and will adjust that actuator to spec.
Times like these and I wish I had a waste gate and mechanical injection. Less fuss more reliable in my experience. Gone are those days.
I have multiple problems though. I believe the old N75 worked fine until the nipple cracked.
Based on the problem that I started the thread with and the feedback here, I believe my actuator needs to be lengthened. I'm completely unplugged from vacuum and now it no longer goes into Overboost limp, but I don't get boost until 2100 RPMS. I'm thinking I have the VNT nozzles open to a spot that acts almost like a waste gate turbo (laggy). BUT I'm glad to have that. Limp means I have a non turbo dose of fuel. It's horrible. I can't keep the car at 70 on the interstate when in limp.
When it gets warmer out AND when I have time, I'm pulling the intake, and turbo and will adjust that actuator to spec.
Times like these and I wish I had a waste gate and mechanical injection. Less fuss more reliable in my experience. Gone are those days.
cfa5
Veteran Member
there you go,
only a hand full on here mentioned for you to adjust
let us know
only a hand full on here mentioned for you to adjust
let us know
UhOh
Top Post Dawg
I've rung up over 120k miles between three ALH cars (one only 11k miles) and have had ZERO turbo/vacuum issues. I have yet to touch anything, even hoses (kind of hate to admit that). 208k miles on one car. 168k on another: this one was from Minnesota; came to me w/o a splash shield (bad idea, especially in an environment like that).
Nevada_TDI
Top Post Dawg
Well, uh, no. If you make the actuator arm longer you are setting the turbo to boost even later then it is now.