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Go Back   TDIClub Forums > TDI Model Specific Discussions Areas > VW B5 Passat TDIs

VW B5 Passat TDIs This is a general discussion about B5 Passat(>98 (2004-2005 in North America)). Non TDI related postings will be moved or removed.

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Old October 4th, 2015, 16:35   #91
QuickTD
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That is not a sensor or a valve, it is just a hollow tube with a heating element around the outside. It is used to prevent freezing of the moisture laden crankcase vapours where they meet the cold intake air stream. It will flow in either direction, as will the "hockey puck" CCV valve on the valve cover.

If you feed pressurized air into the crankcase vent it will blow the dipstick out or the valve cover or the crank main seal depending on which is easier to blow. Use discretion.
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Old December 9th, 2016, 18:15   #92
TheProspector
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Join Date: Aug 2012
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Sorry in advance for the long-winded post, but I need help on my BHW Passat with 245k miles.

I live in the foothills outside of Denver for about 4 months and climb about 1300ft in elevation in about 11 miles on my commute home. About 6 weeks ago my car went into limp mode and gave the p2099 code. I pulled over and found a vacuum line disconnected from the N75 valve. I reconnected the hose, cleared the code and the car ran fine for the rest of that night and the next day until the late afternoon when I was in a little of traffic and limp mode happened again. This time i was pouring white smoke out the back of the car. I pulled over and found that my turbo was broken. Over the next two weeks i changed the turbo(I cheaped out and ordered the cartridge to save money) which went well but I was still constantly getting the P0299 underboost code. So i changed the N75 valve which helped it go from a constant code to an intermittent one. Finally, I checked the adjustment of the actuator stop and rod and found out it was out of adjustment. After adjusting the stop, the car ran fine for about 3 weeks. I took in on a 12 hour round trip drive and had a overboost code once but that was it. Three days ago i started getting the p0299 underboost code anytime i even barely asked anything of the engine. To avoid the code, I was leaving the car in 4th gear to climb hills. Yesterday, trying to merge into traffic, the car lost power again and was pouring white smoke and ate a bunch of oil meaning the turbo probably died again. I found a chaffed wire that I think maybe my underboost issue but my question is if you guys think the underboost code is causing my turbos to break or is it just an unfortunate coincidence of an old part finally breaking along with maybe a ordering a bad part and that breaking? Thank you guys for any help. It's much appreciated.
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Old April 11th, 2017, 07:55   #93
ciz51
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Fuel Economy: Passat-42mpg, Jetta-54 mpg
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On Passat TDI, PD, the Turbo, with No Vacuum, is at zero boost; To Quote martin1810passatsubscriber:

“With a VNT TURBO system you do not dump the air pressure (a/k/a "waste gate" .ed), you dump the vacuum. The vacuum is a very small thing so fine control is easy and lag is much reduced.
So, at start you have 100% vacuum and maximum vanes in turbo so maximum boost.

As engine rpm rise the boost reaches its maximum set point, the actuator % starts to reduce. This reduction in actuator % moves the vanes that direct the exhaust gas onto the turbo impeller. So the actuator % is going down but the boost stays at full.

The actuator % drops because it is venting vacuum (not air). This venting of vacuum gives very fine control of the turbo vanes which gives fine control of the boost pressure. At rest, the turbo vanes are in the max boost position so if they stick, they stick at full boost. So now, even if the actuator vents vacuum and the actuator % drops, the boost stays stuck at full. Most systems are designed for full boost at about 1500 rpm so now when the engine rpm goes higher the stuck vanes allow the boost to rise higher than maximum.

This is not good and the engine drops not limp mode. So constant overboost with a VNT is nearly always turbo vanes sticking and a constant underboost is nearly always a vacuum leak.”
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Old May 10th, 2017, 09:45   #94
deckerfl
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I'd like to chime in on this post.
2004 Passat TDI, 150K Miles, Rocket Chip stage 2
I've had the dreaded underboost error, and the MAF error. changed MAF, Pressure sensor, but in the end, my issue was boost leak. My boost leak was in multiple places. One was a slightly split charge hose, the "S" hose right after the turbo. Replaced that. it got better but still sometimes went into limp mode. Then changes all of the charge hose spring clips, including the one right on the turbo outlet. This one was worn and allowing the "S" charge hose to be pushed out a little, but this was not the real issue. this is the second time I've replaced the "S" charge hose. first time was the cable wear, next time, it split. I'm not replacing the "S" hose a third time, so for the future, I now have After market pieces to replace it, with Ebay piece, like Passat owners use to upgrade to the BV43A turbo.
I finally made a boost leak tester out of a Plastic water bottle (I'll try to post a pic later) and found my new leak. It was in the 90 degree Charge Hose right before the "Throttle" Actuator. I thought I had checked that Charge Hose, but the split was way underneath and I missed it. I replaced that and my Under Boost Codes are gone. , I also did other tests in this thread, checked turbo actuator, vacuum lines, applied vacuum to actuator to make sure it was actuating, and added support to where vacuum line meets actuator like previous posters...
Very useful thread, thanks to all the contributors...

Last edited by deckerfl; July 12th, 2017 at 07:15. Reason: Addding a boost leak test line...
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Old July 12th, 2017, 09:46   #95
deckerfl
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I picture of my Boost Leak Tester. I drilled out the top and bottom of a nicely shaped plastic water bottle and put a 1/4" Air hose attachement on the top.
https://flic.kr/p/VohtcS
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Old August 7th, 2017, 14:06   #96
boobap
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I got the dreaded p0299 code the other day... Wife and I were on a road trip (about 500 miles into it) when wife called me and told me to stop on the side of the freeway because the car has no power. I've gotten it towed back home (very long story) and haven't had time to inspect it. Here is the "setup":

We were driving up a very slight grade just before Baker City, OR at 75. It was about 95 degrees out when she hear a "pop" (she compared it to the sound of running over a cheap water bottle) then it lost power. I'm fairly mechanically inclined, but like I said I haven't had time to inspect it yet and just wanted y'alls input on where to start.

Her saying that it sounded like "pop" leads me to believe it is a boost line that separated. I took the top cover off of the engine to inspect the boost lines on top because I had taken them off to replace the dreaded coolant flange and TD pump gasket.

Any and all input would be great. I will dig into it this weekend and let you know what I find...
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Old August 8th, 2017, 12:34   #97
Windex
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My first places to look would be at the elbow right before the intake/anti-shudder valve, and if that's intact, I would check the s-shaped hose right off the turbo to the cross-tube under the radiator.
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Old August 8th, 2017, 13:21   #98
truman
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After replacing a couple of boost hoses, with significant improvement, the N75 was replaced and that essentially resolved limp mode issues. In the last 6 months, I have had 1 limp mode, which surprised me. Non since that 1 instance. Since N75, turbo response is much better and smoke at WOT is way down. Boost leaks and N75 get my vote.
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Old August 14th, 2017, 07:38   #99
boobap
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As suspected, the lower passenger side boost line popped off the metal tube. It was a "self induced" situation. 3 months ago I deleted the BSM and didn't put the lock back where it should be. So it's been my DD for the last 3 months and it decided to pop out while we were in the middle of nowhere land...point is, always do some good QA before calling a job finished. And don't drink to much while doing these jobs! HAHAHA
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Old May 15th, 2019, 17:20   #100
atikovi
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Just found this thread on a search. Have an 06 Jetta BRM and just had the turbo rebuilt. After installing it the car runs like crap. No power until 2200 rpm, lots of black smoke, P0299 code. If I remove the hose from the VNT actuator it's a whole different animal. Tons of smooth power, no significant smoke. I assume removing the hose keeps the turbo vanes closed so it builds full boost all the time. Ran some tests. Put vacuum to the actuator and the rod moves smoothly and holds vacuum. Checked the N75 solenoid and it puts out good vacuum to the valve. MAF sensor is new. What else can I check?
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Old May 16th, 2019, 11:26   #101
QuickTD
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Quote:
Originally Posted by atikovi View Post
Just found this thread on a search. Have an 06 Jetta BRM and just had the turbo rebuilt. After installing it the car runs like crap. No power until 2200 rpm, lots of black smoke, P0299 code. If I remove the hose from the VNT actuator it's a whole different animal. Tons of smooth power, no significant smoke. I assume removing the hose keeps the turbo vanes closed so it builds full boost all the time. Ran some tests. Put vacuum to the actuator and the rod moves smoothly and holds vacuum. Checked the N75 solenoid and it puts out good vacuum to the valve. MAF sensor is new. What else can I check?

Pulling the hose from the actuator will open the vanes fully. BRM's have a problem with the vanes being driven too far closed due to wear in the vane unison ring. This does not allow a sufficient volume of gas through the turbo and causes huge backpressure in the manifold. Once you get over the hump and the turbo finally spools up, the car will run OK. You just need to adjust the vane control lever stop screw. There are several threads about the problem search "BRM stop screw adjustment".
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Old May 16th, 2019, 11:38   #102
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Quote:
Originally Posted by QuickTD View Post
Pulling the hose from the actuator will open the vanes fully. BRM's have a problem with the vanes being driven too far closed due to wear in the vane unison ring. This does not allow a sufficient volume of gas through the turbo and causes huge backpressure in the manifold. Once you get over the hump and the turbo finally spools up, the car will run OK. You just need to adjust the vane control lever stop screw. There are several threads about the problem search "BRM stop screw adjustment".
I've already done the MB 11 charge pressure control test and it showed 960 to 1050. Within the 80-250 acceptable range. Wouldn't that indicate the stop screw is in the correct position?
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Old May 16th, 2019, 12:16   #103
QuickTD
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Originally Posted by atikovi View Post
I've already done the MB 11 charge pressure control test and it showed 960 to 1050. Within the 80-250 acceptable range. Wouldn't that indicate the stop screw is in the correct position?
Yes, it would, but your symptoms sound like a stop screw adjustment problem... The actuator should push out all the way (down) as soon as the engine starts. Confirm that it makes a full stroke during the charge pressure test. Check vacuum as well. You should have around 25" at idle at the pump/reservoir.
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Old May 16th, 2019, 12:30   #104
atikovi
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Actuator hose vacuum goes from 0 to 25" during the test and 17 at idle afterwards. I'll check the stroke next.
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