Weak or dead turbo?

Hello folks, I just picked up a 2002 Jetta. 237 k miles, 5 speed standard.
I picked it up at a good price, the previous owner thought he had a dead turbo. I was not so sure so I pulled the trigger. No code now, probably need it to cycle. I have a ZURICH code reader, pretty good reader. The only thing I see is a #1 glow plug is dead. No problem. I checked the vacuum lines using a generic diagram, replaced many bad lines and checked routing. All seems to be okay now, maybe??? The turbo will boost fine about 5% of the time, the rest of the time SHE ACTS DEAD. I have a hard time getting her above 3000rpm, but sometimes she comes alive and runs normal, 80mph easy. I know I need to give you some codes, but don't have them yet. Being a stupid idiot that I am, I tried hooking the vacuum from the vac pump directly to the actuator valve on the turbo. Nothing! I sucked on the actuator hose to see if the diaphragm was bad, it appears that it will hold the vacuum. I'M thinking maybe the actuator is not opening the waste gate allowing the turbo to spool. But sometimes it does, folks i'm a tad perplexed.

First - there is no wastegate.... Second - there are some really good how-to testing threads (search limp mode) that will guide you through a step by step.

This is one that will work:
http://forums.tdiclub.com/showthread.php?t=179589

Actuator is a good place to start, pretty common for cars that age.

Might just be sticking vanes.


These little levers control the vanes. They get gummed up and don't work freely. Some try oven cleaner but the best way to clean a turbo is to pull it apart.

After removing the verbal boot out of my butt. I took G forces advice and read the treads. Thanks G force, GREAT advice and information. So far I unplugged the MAF,she is running better, may be 50% boost, still a dog but a big dog. I'll recheck my vacuum lines and be prepared to buy a new MAF. I'll check the actuator, but I think it probably is okay. Then if needed I will pull the turbo and check the vanes. Thanks guys, as always your the best. I'll get back with my results, my cel is on probably because I unplugged the MAF

Have you considered a stopped up intake?

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UPDATE!!! Just wanted to give everyone an update. Pulled the plug on the MAF, she seemed to run better. Tripled checked and replaced leaking and torn vacuum lines. Pulled EGR, clean and removed a bunch of carbon out of intake. Tried cleaning the MAF, didn't seem to help, ordered a new one. Checked vacuum at different connections, we are getting sufficient vacuum. Ordered complete vacuum line set. N75 valve does not seem to modulate the vacuum going to the actuator, and it does not click, its appears to be straight vacuum non modulated. Ordered a new n75 valve. My last question is this car, use to be an automatic, it is now a standard, I can feel the detente on the accelerator, passing gear type feel. Does the ecm need to know that this is now a standard, and can this be affecting the turbo spooling. I did not do the swap, it was done by the previous owner and he claimed it cost him 3,500$ to do the swap. Just pulling things out of my butt at this time. THANKS GUYS

Does the ecm need to know that this is now a standard?

Yes! You can do it with VCDS.

Thanks Rrusse, interesting, I'm not saying it was not done at the swap, but I don't know. I have ordered everything else, MAF, N75, VACUUM LINE KIT, the vacuum pump seems to produce sufficient vacuum, so I did not order that. The lines are all good now, but its a bit of a rats nest. NAPA, charged me $40 bucks for vacuum line and connectors, you know Ill never do business with them again. My map sensor seems to read 30, doesn't seem to change, I assumed that is probably okay, Im using a ZURICH code reader, pretty good, BUT????. As I sated in my previous post, the N75 is allowing full vacuum to go to the actuator, no modulation and no buzz so I assume it is bad, now I should a checked the plug to make sure it was energized. I sure hope I didn't waste $50 on the new one I ordered, DAMN! I recently had to send my ECU on my 06 out do to fix a cel code, where the actuator was not talking to ecu. A gentleman in Dallas reprogrammed the ecu and fixed the problem, but it cost me about $500, labor, shipping. I like this this little bastard, but I don't want to spend the bank account on her. Can a local Guru check the ecu compatibility with the manual transmission?

p930man,
All's you need is someone with a RossTech cable, and a laptop with the free VCDS software. Should be someone in the neighborhood.

If you tee a vacuum gauge into the line going to the actuator you should see about 10 inches vacuum at idle.
It should drop when you drive away.

A vacuum pump is more useful, it can check if the actuator (and other things) is holding vacuum.
There's a VW bulletin about the actuator's rusting internally. It has to be removed to check it.
2 nuts, the vacuum line, and a e-clip.
Tie thread or dental floss to the clip so if it flies when you try to put it back on it's easier to find.

While the actuator is off move the arm going into the turbo full range to see if it moved full range freely and does not stick.
I've read some have worked it for 5 minutes to free it up.

In the long run VCDS is more then a scanner and can be used to diagnose problems.
VCDS lite software is free but you need a laptop & OBD2 cable that works with it.

You should buy Bosch electronics for the computer sensors & such.
Many have had issues buying cheap China parts.

"NAPA, charged me $40 bucks for vacuum line"

And they probably gave you the wrong hose. Just rubber?
You really want the Gates cloth wrapped line like this;


https://www.idparts.com/3mm-idvacuum-hose-p-620.html

p930man said:

I tried hooking the vacuum from the vac pump directly to the actuator valve on the turbo. Nothing! I sucked on the actuator hose to see if the diaphragm was bad, it appears that it will hold the vacuum. I'M thinking maybe the actuator is not opening the waste gate allowing the turbo to spool. But sometimes it does, folks i'm a tad perplexed.

Click to expand...

When the engine is started, Vacuum pulls the Actuator arm down solid against the adjustable set-screw. It stays there during idle... release of vacuum by the N75 Valve results in the Actuator Spring pushing the arm up and away from the set-screw ................. Hmmm most people think "vacuum" controls boost.., It's actually just the opposite. Releasing vacuum determines boost. That spring in the Actuator is extremely strong and will push faster than the vacuum pump or stored vacuum can pull against it.

The above is extremely easy to observe looking up from the bottom on the ALH engine in my Vanagon.

And, as others have stated........... No Waste-gate in the VNT Turbos.. just changing the angle of the Vanes that "direct" exhaust gasses across/over/thru the Blades of the Turbo...

You need to get the DTCs...

AndyBees said:

Hmmm most people think "vacuum" controls boost.., It's actually just the opposite. Releasing vacuum determines boost. That spring in the Actuator is extremely strong and will push faster than the vacuum pump or stored vacuum can pull against it.

Click to expand...

It's always confused me because if you to not have vacuum you don't have boost.

AndyBees said:

When the engine is started, Vacuum pulls the Actuator arm down solid against the adjustable set-screw. It stays there during idle... release of vacuum by the N75 Valve results in the Actuator Spring pushing the arm up and away from the set-screw ................. Hmmm most people think "vacuum" controls boost.., It's actually just the opposite. Releasing vacuum determines boost. That spring in the Actuator is extremely strong and will push faster than the vacuum pump or stored vacuum can pull against it.

The above is extremely easy to observe looking up from the bottom on the ALH engine in my Vanagon.

And, as others have stated........... No Waste-gate in the VNT Turbos.. just changing the angle of the Vanes that "direct" exhaust gasses across/over/thru the Blades of the Turbo...

You need to get the DTCs...

Click to expand...

The logic is sound but when I had a massive vacuum leak at the brake booster line, it wouldn't make boost at any RPM or throttle position, could it have been the vanes were too far advanced and in essence stalling the turbo?

Andy, I know you've been in and out of these engines and trust your knowledge, but I've gotta see this... hopefully tomorrow I can hook the mighty vac to the turbo actuator line and watch it...to think of it I've only heard of the test to check the movement but never how it actually worked. This is intriguing.

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I get about 10 inches vacuum at idle and it drops when I take off.
Operation agrees with Andy but it still defies why with no vacuum it's no boost.

wonneber said:

I get about 10 inches vacuum at idle and it drops when I take off.
Operation agrees with Andy but it still defies why with no vacuum it's no boost.

Click to expand...

It has to be like when you take compressed air and blow on a fan, too steep and it slows, too shallow and it slows also...but when you get it spinning you can change angles and make it go faster

The angle of the vanes are too steep to efficiently spin the turbo, seems like a smarter system than you'd think

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"It has to be like when you take compressed air and blow on a fan, too steep and it slows, too shallow and it slows also
...but when you get it spinning you can change angles and make it go faster" WildChild80

Hmmm, this is why the factory VNT settings are so critical,
the "flow bench testing" that I've read about. Downright educational
discussion gents, thanks!

Rrusse11 said:

"It has to be like when you take compressed air and blow on a fan, too steep and it slows, too shallow and it slows also
...but when you get it spinning you can change angles and make it go faster" WildChild80

Hmmm, this is why the factory VNT settings are so critical,
the "flow bench testing" that I've read about. Downright educational
discussion gents, thanks!

Click to expand...

Up until a few hours ago I thought vacuum=boost...

I agree, even on cars that are flirting with 2 decades old, I'm still learning and am fairly amazed at the design.

Good learning here fellas

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UPDATE Thanks to all of you and your feed back. Replaced the n75, nothing. Replaced the MAF and the vacuum lines. She runs pretty good now. Different than any of my other TDI's. This is my first ALH. kinda a dog, but hit 3k and the Greyhounds come out, holy smokes does she run. I need to re read everybody's comments and digest what is n ext. Again, folks I bow to your knowledge!

p930man said:

UPDATE Thanks to all of you and your feed back. Replaced the n75, nothing. Replaced the MAF and the vacuum lines. She runs pretty good now. Different than any of my other TDI's. This is my first ALH. kinda a dog, but hit 3k and the Greyhounds come out, holy smokes does she run. I need to re read everybody's comments and digest what is n ext. Again, folks I bow to your knowledge!

Click to expand...

It shouldn't take until 3000 to get decent power. Check for correct actuator movement

I didn't see if you checked you were getting at least 20 inches of vacuum from the pump.
You need that much to pull the actuator fully.

The nipple on the vacuum pump is known to be loose. Some fixed it with silicon or epoxy.

There is a VW bulletin about the actuator rusting inside. You have to take it off to check it.
2 nuts, the vacuum line, and an e-clip holding the rod to the arm going into the turbo.

While it's off check if the arm moves freely full range.
Some have freed it by working it full range for 5 minutes.

When you put the e-clip back on tie some thread or dental floss on it so if it flies you can find it easier.