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Discussion Starter #1
Hi all,

Been searching the site here looking for info. Recently, I've been getting some intermittent P0299 underboost errors on the Engine 2 side. I checked measure block 11 and the boost appears low but is following the request normally. From searching, it appears this may be an issue of leaks in vacuum system. Additionally, I've been having some issues with the brakes where following an initial press of the brake pedal, it gets really stiff, like a loss of power steering. Both of these items lead me to think the Vacuum lines are failing and since they are almost 12 years old now, figure it would be best to replace all the hoses and hopefully fix up other minor issues as well. However, I can't seem to find a vacuum diagram for the V10. I have elsaWin and don't see it there either. If anyone has this, and can share I would be super thankful. Also, if anyone has other ideas what could be the issue, I am happy to listen in case the vac line replacement doesn't correct these issues. Thanks in advance.

2007 V10
 

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Discussion Starter #3
That's awesome! Thanks, I did not know about that site. Gives me at least a good start. Now just need to see where the the lines connect to the actuators.
 

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V10 turbos are electronically actuated, so your boost problem can not possibly be related to vacuum lines and leaks. Instead you either have a leak in the charge air hoses, or the turbo itself is not able to supply the required boost in the first place, because of being worn or having stuck/carbonized vanes. Or your MAP sensor is defect, but that's the least probable of all the possible culprits.
 

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Discussion Starter #6
That explains not seeing the vacuum lines for the actuators in the drawings. Is it possible to see the Engine 11/passenger side turbo actuator, without tearing much apart the vehicle? Also, if charge lines are good, and no leaks, would "Revive" or the Wynn turbo cleaners be helpful to unstick the turbos? When I bought the treg 2 years ago, the previous owner mentioned the turbos were replaced recently at the dealership. Also, I thought when it's an issue with the turbo it's usually an overboost issue, or maybe I need more info.
 

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The vacuum issue for the brakes is most likely the vacuum tube that runs across the firewall and connects the two n18/n75 valves... I just replaced it in both my 2004 V10tdi’s. You could also inspect it for cracks and repair/splice it with silicone tubing if you like.

Turbo issue could be several things. Intake leaks, MAP sensors and stuck/sticky activator rods come to mind.
 

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A leak in the vacuum system will not affect the turbos. The Vacuum line splits of at the right hand side of the firewall to the EGR system. I suggest pulling that pipe and blocking it to try an isolate your vacuum leak. I've plugged mine about a year ago and now my intakes stay nice and clean!

As for your low boost issue, I suggest plotting the boost pressure from both turbos and comparing them to requested vs actual.
 

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Is it possible to see the Engine 11/passenger side turbo actuator, without tearing much apart the vehicle?
You should be able to have a look at them from below, after you've removed the bottom engine cover / skid plate.

Also, if charge lines are good, and no leaks, would "Revive" or the Wynn turbo cleaners be helpful to unstick the turbos?
Any turbo cleaner that's supposed to be injected into the system pre-combustion (so, into the fuel tank or into the air intake) is snake oil, because they can have only negligible - if any - cleaning effect, because of, you know, getting mostly burnt and destroyed in the combustion process. Also, if you have stuck vanes, the vanes themselves will prevent anything from reaching the carbon deposits that hinder their movement.

That said the V10 turbo actuators are known to fail frequently earlier than the turbos themselves, so, you might have an issue with the actuators. However, once the actuators begin to fail and do not move the rods fully from end to end, it's only a matter of time until carbon deposits start to collect in the "dead" range at the vanes, so, that even if you repair the actuator, you might still also have to clean the actual turbo assembly afterwards anyway, because that has now also degraded as a consequence.

When I bought the treg 2 years ago, the previous owner mentioned the turbos were replaced recently at the dealership. Also, I thought when it's an issue with the turbo it's usually an overboost issue, or maybe I need more info.
It really depends on what's causing the problem. Stuck closed wastegate vanes are causing over boost, stuck open vanes are causing under boost. Actuator problems can cause both depending on how they fail.

But as said previously, you might have a charge air leak somewhere, which would also cause under boost, or a MAP sensor failure, which again, can cause both - even though in this case the boost problem is only apparent, not actual.
 

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Discussion Starter #10
Thanks guys for all the info. I'm planning on getting a better look tonight. That being said. I'm posting my turbo responses for both sides of the engine. Green indicates the requested boost and yellow is measured boost. The lighter shades are the more properly running Bank 1/Driver side, and the darker shades Bank2/Passenger side. I'll post my VCDS scan as well, but it is mainly only the P0299 error and "radio" for a non VW radio, and some low battery triggers I haven't cleared yet.
D2W.PNG
turbographP0299.png
 

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1. Look for a part of road with a heavy incline, but low traffic.
2. Come to a standstill at the start of the incline.
3. Start logging engine MVB 003, 010, 011 in a new file. Do not look at VCDS again until you stop!
4. Put Tiptronic shifter in "manual" mode
5. Floor the pedal and keep it there
6. Shift up manually whenever revs are about to reach the red section (4000 rpm on TDIs, 6000 rpm on petrols)
7. Repeat step 6 until you reach the legally allowed speed limit, but at least 100 km/h or 60 mph.
8. Decelerate to standstill.
9. Stop logging
10. Repeat steps 2-9. a few times
11. Cruise at least a mile or two to let the turbo cool down somewhat before shutting the car down
12. Send the actual log files, not the graphs, because those can be generated by anyone based on the logs, but you can't read neither the labels, nor the exact measured values from the latter
 

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Discussion Starter #12
I'll try to get this done right away. My only concern is would the P0299 error with Limp mode negate this information? I am concerned as it seems to get triggered once RPMs get to about 2-2.5K or higher.
 

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Well, obviously once limp mode will be triggered, there will be no point in continuing. However, we should be able to see what leads up to that fault. Also, it should take a while until limp mode gets triggered. The ECU just won't raise most fault codes immediately after it encounters an error condition, but only then if it seems to be consistently present for over a period of time. This prevents false positives and one-off errors (which really happen all the time) from crippling the driving experience.

So, maybe turn off the engine and ignition, wait 30 s, and then start it again right before beginning the test, so you won't trigger the fault right away. And of course do the logging for both of the turbos/engine controllers. By repeating the test on the same part of the road and under the same load conditions, you'll get a log of the two turbos that are essentially directly comparable to each other.
 
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