Help needed with BEW Turbo Actuator adjustment

Jlane330

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Ok, we were getting the overboost code and limp mode under harder acceleration, so I ordered a turbo install kit and set out to clean the turbo vanes. A little back history first though...
- The car is new to us. 216K miles, lots of documentation from previous owners.
- 2005 Jetta Wagon with 5sp manual
- I have receipts for replacements of the N75, turbo actuator adjustment, MAF sensor, etc
- The PO claimed he replaced the turbo and that the car has a Malone stage 1 tune. Did not have receipt, but claimed turbo came from tdiupgrades.com. Actuator can is a Smart Actuator and appears to be line new appearance.
- EGR was deleted, but cooler was still installed.
- No engine codes other than overboost on occasion with spirited driving. Engine seems sluggish until about 2K rpm, then it pulls well.
- We are at approx 4500ft elevation

We dug into this by first doing some diagnostics. Put a vac gauge on the turbo actuator vac hose and ran the Group 11 test in VCDS. Vacuum goes from zero to 23-24, which seems correct. Used my Mighty Vac and connected to the actuator can, and it holds pressure fine, but arm didn't move much. With that info, we started by removing the intake, cooler and turbo, of course. Cleaned up the intake manifolds (split them and cleaned each half separately), then disassembled the turbo. Ends up the actuator module wasn't moving much because it was adjusted in essentially a fixed position (actuator rod was shortened such that the lever was against the stop screw). Removed the actuator and the lever flips back and forth easy and freely. We disassembled the turbo vanes anyways and cleaned it all up. Did NOT see any issues in there and cleaning was easy. Researched a ton to find instructions on how to adjust the actuator and stop screw. Set it so the actuator rod was fully extended with the vane lever in full out position, and set the stop screw with the actuator at 20 in Hg. Actuator started moving at about 4 in Hg it seemed.

Reinstalled everything with new gaskets, nuts, etc. The EGR cooler didn't make it back into the car (plugged the vac line, rerouted the coolant lines with couplers). Definitely need to get a good cable hose clamp plier!). Car started right up, went into VCDS and tried running the Group 11 test and initially it ran ok, but only got a change of 20-30 in boost pressure (I understand it should be 80 minimum up to 250). After running it several times, it now doesn't fully run, instead it ramps up the RPM and as it gets close to 1407rpm the rpm jumps to 1550-1600 and then comes back to idle. Obviously something isn't right.

Went for a drive and it has no power. We data logged the drive down the road and actual boost pressure is WAY low compared to commanded. Following some instructions I found on myturbodiesel, I tried backing the set screw off more. I also tried shortening the actuator rod (for more initial boost). At idle I see 829-849mbar...it's not even on the Live Scope display. It basically didn't change after the adjustments, but a test drive reveled even less power (couldn't get past 3K rpm in 1st gear). No trouble codes showing, nothing else seems amiss. Obviously I'm missing something.

- Does the Smart Actuator need to be calibrated/linearized? If so, how? I found discussions about it, but nothing seemed definitive.
- How do I properly adjust the actuator rod and stop screw?

It's obvious that the turbo is not the original KP39, but I have no idea what it actually is. It appears to have a VNT 15 inlet (stock size for KP39?), and the VNT 17/KP39 style outlet on the compressor side. The compressor looks like a billet 6+6 wheel. The exhaust turbine wheel is shaped like a VNT15/17 style with the cupped fins, not the smooth fins of the KP39. The actuator rod uses an E-clip/ball joint to connect to the turbo, not two nuts on a threaded rod, again like the VNT 15/17 pics I've seen. The smart actuator looks like a the same one from Kerma, not the stock KP39 style electronics. No name brand in the casting, no ID plate on the side, nothing. Shaft play seemed VERY reasonable, so I tend to think it's in good shape, just not idea what it is. Any advice on identifying it so I know what I'm working with?

Sorry for the long post, but trying to be complete and accurate. I'm tired of working on this thing and guessing, and could really use some help from those experienced with these turbos. Thanks in advance!
 

PakProtector

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If you messed with the stop screw, that is a far different thing vs the actuator arm length. The stop screw sets the minimum open vane position. Too far closed is bad, and so is too far open. The fine folks at Xman turbos have a decent video of the vane stop screw setting process. It isn't exact, but evidently quite workable.

Have no idea what it is, but given the billet compressor wheel, could be a bigger one( a hybrid build then).
cheers,
Douglas
 

eddieleephd

Top Post Dawg
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2002 jetta Wagon
If you have a new turbo I recommend against adjusting the actuator! That's likely not the issue. N75 or vacuum issue should be checked first.
They're adjusted from the manufacturer and generally adjusted better than we can.
 

Jlane330

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If you messed with the stop screw, that is a far different thing vs the actuator arm length. The stop screw sets the minimum open vane position. Too far closed is bad, and so is too far open. The fine folks at Xman turbos have a decent video of the vane stop screw setting process. It isn't exact, but evidently quite workable.

Have no idea what it is, but given the billet compressor wheel, could be a bigger one( a hybrid build then).
cheers,
Douglas
Thanks for the reply, it is much appreciated. I'm not certain I have my terminology correct, coming up to speed on turbos, TDI's, etc. Can you point me in the right direction concerning this video from Xman Turbos? I have not been able to find anything from them so far. I have seen other videos talking about adjusting the rod and stops, but nothing about starting from scratch.

It is likely that I have the stop screw adjusted completely incorrectly. Thing is, I definitely couldn't guarantee that it was correct before. The entire setup was adjusted such that the VNT vanes were fixed in position and the vac can wasn't doing anything. My confidence in the shop that worked on this car is waining. They are supposedly a good VW/Audi specialty shop, but given the transmission leak from the bell housing even though they replaced the rear main and input seal about 10 months ago makes me wonder. I digress.

In an effort to better understand how this works, a few questions/comments. Please correct if I have something wrong.
- The stop screw controls the position of the vanes where maximum boost would occur. If I turn the screw in to limit the motion of the VNT lever, I should get less boost.
- If I extend the actuator rod, it will preload the VNT lever and motion will begin to happen at a higher vacuum level. This will also raise the vac level required to hit the stop screw.
- Is it typical for the VNT lever to be preloaded by the vac actuator? I haven't seen any mention of this and went about the adjustment a different way...likely wrong.

What I did with the turbo out if adjust the actuator rod until the fully extended position was at the stop of the VNT lever rotation. In other words, no preload, but no motion either, just against the stop. Then I adjusted the stop screw until it contacted the lever when the vac can had 20 in Hg of vac. Obviously this is wrong, but I think I can correct it with trial and error (methodically).

I think what's happening is it's getting a boost spike while trying to run the Group 11 test. This is making the test fail, and possibly putting it into limp mode and thus no boost. I can't confirm this is happening, no boost gauge, but seems like it. I'm thinking I'll turn the stop screw in several turns to limit boost and see what happens. If I can run the test, then I should see the difference in pressure between off and on mode, and fine tune the stop screw until I get between 80-250 mbar change during the test. I can start very small and back out the screw until it's giving the correct boost, assuming the turbo makes the correct boost at 1400 rpm and the MAP sensor is reading correctly. I think this should work since the ON/OFF test goes from 10% (OFF) to 90% (ON). Basically, it should be against the stop screw or fully closed (is that right, or is it called open). Anyways, it should be going full motion each way against each limit.

Once the stop is set, I can then adjust the rod length such that it hits the stop screw at 18 in Hg. Then I can test drive and log...hopefully seeing supreme performance, lol!

Does this sound like a reasonable approach to getting it reset? I can change the stop screw fairly easily with the car on ramps, even while running. I believe the issue yesterday was that it was in limp mode (but no codes being read and no light on dash) and I never cycled power. If not, no idea what was going on.

If you have a new turbo I recommend against adjusting the actuator! That's likely not the issue. N75 or vacuum issue should be checked first.
They're adjusted from the manufacturer and generally adjusted better than we can.
Well, I wish I could be certain that the stop screw was set correctly, but no way I trusted that was true. Unfortunately it's already been adjusted by me, so it's definitely not set any more. I did check the N75 operation and vacuum module, and both seem to be functioning correctly. Everything to the turbo seems to be correct.

EDIT: Thanks for all the info. I guess writing this is both a brainstorm on how to proceed while looking for ideas and advice. I really do appreciate any/all comments.
 

burpod

teh stallionz!!1
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82 rabbit vnt ahu, 98 jetta vnt ahu, 05 parts car, 88 scirocco.. :/
I have not read all the info yet, bit fwiw, tdiupgrades.com would be a cheap Chinese turbo. Someone correct me if I'm wrong. May have no bearing on your current issues
 

Jlane330

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How To Rebuild A Garrett VNT17 Turbocharger! - YouTube

That one came from their GT1749VB ebay cartridge auction.

Douglas
Thank you! That's one of the videos I found this morning when searching. Makes sense how he did it. I don't have a known good stop screw adjustment to compare to unfortunately.

I have not read all the info yet, bit fwiw, tdiupgrades.com would be a cheap Chinese turbo. Someone correct me if I'm wrong. May have no bearing on your current issues
You may be right. I don't have any proof of where this turbo came from, was just sent that site from previous owner...he claims he bought the turbo there. On their site, then claim Poland made turbos iirc? Unfortunately, my turbo has nearly zero markings on it to help identify it.
 

burpod

teh stallionz!!1
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82 rabbit vnt ahu, 98 jetta vnt ahu, 05 parts car, 88 scirocco.. :/
I can't say for sure what it is on your turbo, but the 17, 17/22, 1856 the set screw was right around 3mm protruding. I'd say 4mm max. I would guess 3mm would be pretty close to what it should be
 

Jlane330

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I can't say for sure what it is on your turbo, but the 17, 17/22, 1856 the set screw was right around 3mm protruding. I'd say 4mm max. I would guess 3mm would be pretty close to what it should be
Awesome, thank you so much for a starting point!
 

burpod

teh stallionz!!1
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82 rabbit vnt ahu, 98 jetta vnt ahu, 05 parts car, 88 scirocco.. :/
Are you sure all vacuum lines etc are connected properly again? Check valve facing the right direction?

When the car is idling, if you use a long socket extension (or just finger if you can), the vnt lever should be in the full downward position - full vacuum - if you can push down on it and move it farther down while idling, then you have a vacuum problem.

Im quite sure if set screw is 3mm protrusion, and actuator rod is set at a length so it begins to show movement at 3-6hg, and hits the stop screw at 18-22hg, your car should run decent enough. If not, must be something else simple your missed or messed up?
 

Jlane330

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Are you sure all vacuum lines etc are connected properly again? Check valve facing the right direction?
Pretty sure. I put a vac gauge on the line to the actuator and ran the N75 test in VCDS. I see the gauge go from zero to 24-25 in Hg. It seemed to be functioning correctly. I plugged the vac line that went to the EGR cooler flapper valve, so shouldn't have a vac leak. Where is the check valve? I didn't disconnect a check valve that I know of, so I assume it's correct.

When the car is idling, if you use a long socket extension (or just finger if you can), the vnt lever should be in the full downward position - full vacuum - if you can push down on it and move it farther down while idling, then you have a vacuum problem.

Im quite sure if set screw is 3mm protrusion, and actuator rod is set at a length so it begins to show movement at 3-6hg, and hits the stop screw at 18-22hg, your car should run decent enough. If not, must be something else simple your missed or messed up?
With the car up on ramps tonight, I crawled under there while running the Group 011 On/Off test in VCDS. Using a mirror, I could see that the VNT lever is hitting the stop. I started at roughly 3mm of stop screw showing and ran the Group 011 test over and over. It finally settled at a delta of 30 in Hg from off to on. I started adjusting the stop screw little by little (backing it away from the lever so it travels more) and then retesting over and over. I finally was able to get it to show a delta of 80 in Hg. The stop screw is roughly 1.5mm protruding at this point. I confirmed each time that the lever was fully traveling to hit the stop using my mirror and flashlight (easy to see).

Then, I adjusted the actuator rod such that the lever contacts the stop screw at 18 in Hg. Reran the Group 011 test a few times and it seems to "relearn" a little each time. Not sure what's going on, maybe it's adjusting fueling? The turbo vanes are moving the same amount each time, but it's obvious something else is changing because the boost pressure gradually goes up each On/Off cycle until it settles. Anyone know what's actually going on in the computer during this cycling?

Anyways, I confirmed that the actuator starts to move around 5 in Hg (not really adjustable it seems, but is 'correct' based on what I've read), hit the stop at 18 in Hg, and has a delta of 80 in Hg in the On/Off test. Time for a test drive.

Test drive was ok, but started out really sluggish. As I drove more, it seemed to get better and better. No underboost/overboost codes, but did have a pending code stating the range couldn't be met (something like that). It really seemed like it was relearning something, but in the end, I have a feeling the actual boost is lower than commanded boost. I need to review the log data tomorrow to confirm. I saw a few numbers on the screen that showed this to be true, and the performance felt like it too. If it's indeed true, I will need to decide what to adjust. I think I need to adjust the stop screw out more, then retest/redrive. Not sure how sensitive it is, so will adjust 1/2 turn at a time I guess. Maybe it becomes more sensitive the closer I get to the right setting?

One issue I'm having is with VCDS Live Data. I can't get the scale on the left reset so I can actually see the pressure setting. It starts at 900 mbar, and the lowest value I see during the test is 816mbar with a a max of 897mbar tonight during the Group 011 test. I changed the settings in preferences, but it never updates on the screen. Any idea why not, or what I'm doing wrong? I tried restarting the software, etc. Settings are still correct in preferences, but never actually show up on the screen correctly. No doubt VCDS is a useful tool, but the usability of it leaves a bit to be desired (I thought EFILive had quirks, haha).

Thanks again for all the help! Feels good to make progress. Hopefully fine tuning will give some nice results.
 

Jlane330

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Still struggling with this car, but have several data logs and more insight into what's going on...I think.

So, been making adjustments to the actuator rod and then test driving/logging to see how the actual boost follows the requested boost. Summary: it follows it, but at a much lower level. In other words, the shapes are the same, but the actual boost is low. Adjusting the actuator rod isn't making any gains here (have tried a range of about 7 turns total). Adjusting is 1.5, sometimes 2 turn increments.

Things I know/observations:
- N75 test (group 011) shows a response. About the best I can get is 80mbar difference regardless of stop screw location and/or actuator rod adjustment. Put a vac gauge on the line and I see it go from 0 to 23ish inHg)
- I don't see any vacuum issues in the lines. I have a good source of vacuum (23 inHg at idle). Things seem in tact here.
- The actuator rod definitely moves in and out, against the stop screw and away. I can observe this under the car while the test is running. Nothing notable.
- I don't see any evidence of boost leaks, and can't hear anything. Traced the hoses from the turbo to the intake. No oil seeping, even on the lower hoses at the intercooler connection. Everything looks/feels tight.
- The MAF sensor...supposedly replaced recently by the shop. Looked at it's values and it seems to hover around 365 mg/str at idle, and only ticks up to around 385 at 3000 rpm with no load. I would have expected a MUCH bigger increase than this based on that I've read. Seems bad (more below).
- Swapped the MAF with another I have. No idea if the other is any good, came off a low mileage car I have sitting here (that's not running due to auto trans issue). No change in values, still in that same range (400ish). Maybe I have two bad MAF's...
- I unplugged the MAF and it basically drove the same (really slow and anemic). Noticed that the stock value is 550 mg/str, much higher than anything I've seen with the sensor plugged in.
- I am logging the charge pressure control duty cycle % along with boost (requested and actual), vehicle speed, engine speed, MAF (actual), Accel pedal position.
- I keep getting a pending of code P0299- Boost pressure not met...Underboost. I can tell immediately when this code sets and then all of a sudden the car drives better (slightly, but noticeable). The data shows that the charge control duty cycle drops to 9.9% (no boost) at higher accel pedal positions. In other words, it pulls boost with more throttle after a point (approx 70% and higher accel pedal position). Why does it drive better otherwise when this code is pending? I haven't logged anything fuel related yet...
- VCDS is really frustrating. Sure, it works, but very clunky and a hassle.

Questions:
- Can I log the actual actuator position (from the "smart" sensor)? Didn't see this in VCDS.
- My understanding is that a bad MAF will cause power loss. Not sure what to expect when unplugging the sensor. I *think* if the car drives the same with the sensor unplugged, then it confirms a bad MAF. Is this correct?
- Any way to test the MAP sensor? Maybe my low boost isn't actually low boost, rather maybe it's a bad MAP not measuring correctly? I *assume* I'd have decent performance until the underboost code is set, but maybe not. Maybe it's fueling based on the MAP sensor reading? Not sure how the MAP plays into the control system at this point.
- Possible that the exhaust is plugged (it's stock)? Maybe the intercooler is plugged with old turbo bits? I may pull all this to confirm it's clear.
- The flappers in the lower intake...any way to test and confirm these are working as intended? If these are not working properly, what should I see? Can't imagine this is affecting boost pressures, but maybe so?

To summarize, making changes to the actuator rod and stop screw don't seem to be netting much in terms of changes/gains. Small changes observed, yes, but nothing big in spite of making big changes to both methodically. Seems maybe something else is wrong...
 

Jlane330

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Here is a log I took this morning. Blue line is requested boost, Orange is actual boost. BTW, are my images showing up (including this one)?

 

BobnOH

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central Ohio
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From a bit of quick research, it seems the only thing the smart actuator does is provide feedback to the ECU. Most frequent issue with those is bad wires. One thing to keep in mind is the actuator works sort of backwards, more vacuum to the unit equals less boost.
To simplify, use a vacuum pump and gauge to adjust the rod so it just starts to move at 3.5 to 5.0 "/Hg. A simple test is to watch that it moves all the way over when you start the car.
A bit more discussion of rod and stop screw adjustment here.
We often get deep in the weeds with these things, when it is really quite simple.
 

Jlane330

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From a bit of quick research, it seems the only thing the smart actuator does is provide feedback to the ECU. Most frequent issue with those is bad wires. One thing to keep in mind is the actuator works sort of backwards, more vacuum to the unit equals less boost.
To simplify, use a vacuum pump and gauge to adjust the rod so it just starts to move at 3.5 to 5.0 "/Hg. A simple test is to watch that it moves all the way over when you start the car.
Thank you for that link. Yeah, I was hoping that the ECU would share that feedback so I could confirm that the actuator was actually moving while going down the road and following the duty cycle %. I DID visually confirm while on ramps at idle and during Group 011 testing.

I inspected the wires/connector as well and didn't see anything out of place. I'll take another look at it though to confirm. Trying to check everything over yet again.

Are you sure more vacuum = less boost? Based on my logs, that doesn't seem correct. When the N75 opens (duty cycle -> 90%), vacuum is present at the actuator, and the boost pressure goes up. When the N75 closes, no vacuum is present and the boost drops. My turbo is a Garrett style where the actuator pulls the rod under vacuum, and a spring pushes the rod with no vacuum.

I started with a vacuum pump and gauge and adjusted it that way. Not sure it's a sure fire way though given my stop screw location isn't necessarily correct. See, what's the right place to stop at 18 in Hg is the stop screw is wrong? As for starting movement, it seems like the actuator starts moving between 4 and 5 in Hg at all times (mounted or unmounted). Is the actuator rod preloaded in some way (actuator spring with longer rod) where this would change? I honestly haven't figured out the starting movement thing, but have measured it over and over and it seems to always be between 4 and 5. I have tried extremes, as in making the rod really long so it starts movement later, and made it really short in case it'll add boost earlier.

A bit more discussion of rod and stop screw adjustment here.
We often get deep in the weeds with these things, when it is really quite simple.
No doubt, I'm well into the weeds on this now. I went from overboost conditions (but it ran well above 2K rpm when not in limp mode), to not being able to make but about half the requested boost. To overboost, the actuator was adjusted so the vanes didn't move...it was shortened until the lever was solid against the stop screw. The stop screw stuck out several mm. I've gone far beyond those settings now (really short stop screw) and can't get much boost.

To me, this feels like something stupid...maybe my son left a rag in the intake pipe when he was cleaning it or something...I'm going to go pull it now and see if I can find an obstruction. Maybe the MAF died and it's all coincidental, but does a marginal MAF affect boost to these levels? Maybe the MAP died?

Thanks again for the thoughts on this! This shouldn't be this hard, and yet, it's absorbing a ridiculous amount of time and money...
 

Jlane330

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I can confidently say that the intake from the air filter box to the intercooler inlet is clear, no obstructions. Turbo shaft spins smoothly as well.
 

eddieleephd

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2002 jetta Wagon
Im quite sure if set screw is 3mm protrusion, and actuator rod is set at a length so it begins to show movement at 3-6hg, and hits the stop screw at 18-22hg, your car should run decent enough. If not, must be something else simple your missed or messed up?
I have seen this statement many times before and it is absolutely false! Is a misconception that has no basis. Reality is that the actuator should start to move at 3-6 and if it doesn't then it's bad.
When the actuator starts to move then the mechanism in the turbo begins to move, however, this has nothing to do with the adjustment of the turbo...
The only way I know works to adjust the turbo is by running body logs and fiddling with it.
That's why I would recommend not adjusting a new turbo. They take a while to break in, however, are adjusted correctly from the factory.
 

burpod

teh stallionz!!1
Joined
Nov 27, 2004
Location
cape cod, ma
TDI
82 rabbit vnt ahu, 98 jetta vnt ahu, 05 parts car, 88 scirocco.. :/
I have seen this statement many times before and it is absolutely false! Is a misconception that has no basis. Reality is that the actuator should start to move at 3-6 and if it doesn't then it's bad.
When the actuator starts to move then the mechanism in the turbo begins to move, however, this has nothing to do with the adjustment of the turbo...
The only way I know works to adjust the turbo is by running body logs and fiddling with it.
That's why I would recommend not adjusting a new turbo. They take a while to break in, however, are adjusted correctly from the factory.
what exactly is false? i'm not exactly sure what you are saying here... the numbers "3-6" and "18-22" correspond to when the vanes are fully open and fully closed . if the set screw is in the right place, 18-22hg should be hitting the stop. the exact number i do not know or remember what it should exactly be for a given stock ecu and turbo. if the actuator (or set screw) has been changed, you need to find the right length(s) such that target and actual boost line up as best they will. the same goes for a tuned ecu and/or custom turbo/etc, and the exact number will not be exactly the same for across different setups/tunes.

although i do agree, do not fiddle with the actuator until you have taken logs and ruled out any other culprits when it comes to boost issues. if you are tuned however, the n75 map values may not coincide with where your vane actuator is at and may need tweaking to get it "aligned".

i have never heard (or can imagine why) of needing to break-in a turbo "for a while" - other than maybe 10-20 miles (WAG) before really getting on it.
 

burpod

teh stallionz!!1
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82 rabbit vnt ahu, 98 jetta vnt ahu, 05 parts car, 88 scirocco.. :/
i like to log with vcds, and then re-play it with vc-scope. you can't have both programs running at the same time, so make sure you close one or the other. start vc-scope and open file, should default to you ross-tech Logs directory, open it. hit the fast forward to watch it at the speed you can process.
 

eddieleephd

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Asheville, NC
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2002 jetta Wagon
what exactly is false? i'm not exactly sure what you are saying here... the numbers "3-6" and "18-22" correspond to when the vanes are fully open and fully closed . if the set screw is in the right place, 18-22hg should be hitting the stop. the exact number i do not know or remember what it should exactly be for a given stock ecu and turbo.

i have never heard (or can imagine why) of needing to break-in a turbo "for a while" - other than maybe 10-20 miles (WAG) before really getting on it.
The adjustment as stated beginning to move at 3-6 because as I said earlier the actuator begins moving then if it's good. And hitting the stop between 18-20 still leaves a lot of play and will be difficult to adjust without logging and fine tuning.
Putting on a new actuator it's easiest to screw on to the rod until the actuator will bolt without moving the rod or binding.
Break in is all about the way the turbo works. Everything starts out nice and tight and it takes a bit for it to move as freely as it will begin to. Adjusting it by logging when new will often cause overboost issues later, I learned this the hard way.

Adjusted to be relaxed with veins closed is in my experience the easiest, and running logs to fine tune the best.
Of course this is easiest done with it on a work bench.
 

Jlane330

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I appreciate the feedback and support, thank you very much! I was able to spend a little time with it yesterday and did the following:

- Removed all plumbing from air filter to intake manifold (except the intercooler itself) and closely inspected for any issues/cleaned. I do not see any evidence of leaks, all connections were dry and tight (oil inside tubes, as expected). I did snap a few pics of the compressor wheel in case it's helpful in identifying the turbo.
- Traced down all the vacuum lines. Tested the vacuum actuator on the intake manifold, it's moving freely and under reasonable pressures. I see not issues with any of the lines. The thought was that maybe I had a vac leak while driving causing issues, perhaps a different valve was opening and causing that. Doesn't seem to be the case.
- Reran the Group 011 testing and played with the stop screw position only. I backed it out nearly completely, put it in so it protrudes about 4mm, and a few settings in between. The actuator rod is definitely moving full range (visual confirmation). The result is odd though. Regardless of the stop screw position this time, I only see a change of 20-30 mbar in pressure change during the ON/OFF testing.

Some questions about VCDS:
- From what I've seen and read, Group 003 should be MAF specified vs actual. I've seen screenshots on other websites showing that exact thing. Why does mine say EGR? Is this really EGR, or a MAF reading? Note that the Group 003 EGR actual does NOT match the Group 010 MAF actual value.


- When I unplug the MAF sensor, the value is fixed at 550 for both EGR and MAF actual. THis would indicate to me that Group 003 is actually mislabeled and should be MAF? My EGR is blocked, so either this is a made up number from the tune to keep the computer happy or it's actually the MAF reading, which doesn't match the Group 010 reading. Not confidence inspiring in the least.


- There is an information bubble stating the idle and full load reading range for the MAF. These numbers are similar to those I've seen on another website concerning testing the MAF. Thing is, why does MAF depend on load? Shouldn't it simply be based on RPM? There isn't a throttle blade to regulate the airflow on a diesel, so seems MAF should be directly proportional to RPM. What am I missing?


Back to diagnosing the issue:
It would seem that I possibly have two things going on here, and maybe they are related/coincidental with cleaning the turbo.
- It seems like the MAF sensor is not responding correctly. When revving the engine (in neutral, no load), it got to 500-520 mg/str range. I never saw anything higher than that. The engine wouldn't rev past 3600 rpm initially, then after a couple tries it got to 4400 rpm ish. This seems low, unless it's related to having the parking brake and/or foot brake on? None the less, shouldn't the airflow be 3-4X that of idle airflow? Maybe this died at the same time we removed it. I promise we didn't drop it, wash it, etc. The one from the other car acts the same though (I can't confirm it's actually good). This is from a test drive the other day (MAF actual [blue] vs RPM [orange]). Looks like the MAF is barely responding. At the end I unplugged the MAF, thus the flat line at 550. Performance was about the same, still terrible but a little quicker revving and slightly higher RPM. I was into the throttle all the way each time, this isn't the result of little throttle, although it could be low boost and/or pending P0299 code.


- The turbo adjustments don't seem to be doing much. I went from overboost to minimal boost. The shaft spins freely. The VNT lever arm moves freely...perhaps too freely? I'm starting to wonder if possibly the lever arm isn't connected to the adjuster ring inside the turbo. Not sure how this would happen, but maybe it became disconnected? I'm thinking I might try disassembling the turbo while in the car. I know the cartridge slides out easily as I just had it apart last weekend. Not sure I can get to all the bolts, that might be the challenge. Before I do this, is there any way to confirm that the vanes are moving with the lever? Visually, I can't see them behind the turbine wheel. Not sure how much resistance the VNT lever should have, but it moves VERY easily! Maybe nothing is wrong and it's simply related to the MAF (not fueling enough, not much energy to spin the turbo and create more boost)?

New Parts:
- It seems the MAF might be marginal or dead. Maybe I should replace this first?
- If I want to replace the turbo with a new VNT 17 for BEW...any recommendations on where to get it? I hate throwing parts at this, but this is getting ridiculous.

Thanks in advance for any help! Sorry this so long, trying to be complete with info.
 

Jlane330

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Oh, btw, here is a pic of the compressor wheel and turbo. Anyone recognize what model this might be, what brand, etc?



 
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