Need some help with this one please

[tig_21]

Hello, this is my first post so be easy on me.
I just bought a 2006 jetta 5 speed manual. Has 190,000 miles on it.
I drove it to work just fine yesterday morning but on the way home it lost power in 5th gear going up a small hill. Also, the cruise control stopped working, the light is on but just won't work. I stopped and turned the car off and turned it back on. It seemed to work good but after about 5 minutes of driving, the car lost power again in 4th and 5th gear only. The cc stopped working again as well. This time the check engine light came on. It maintains speed but I can't get any progression or power even at full throttle. I had a guy run a code reader at the auto parts store and he said something about low boost or turbo problems but nothing specifically. I don't know what the specific code was either. So I am curious as to what you all think it could be or if you have had similar problems before. Please help I appreciate it.
I also found this other thread it sounds similar but I thought I would see if there were any other comments to help out. Maybe the N75 valve?...
http://forums.tdiclub.com/showthread.php?t=388145&highlight=check+engine+light+cruise+control

Thanks for any help!

 

[Vince Waldon]

Hi and welcome to the forum.

What you're experiencing is most likely what's known as "limp mode".... the car's ECU detects a problem with the boost system (often when the system is under stress... like climbing a hill) and shuts it down to prevent any further damage to the turbo or engine. Resetting the power resets the car's opinion of the boost system.

There's a ton of info on limp mode here, so rather than rehash it all here again I'd recommend reading thru this definitive thread first... to see if that helps:

http://forums.tdiclub.com/showthread.php?t=179589

The fact that the check engine light is on means that the car has an idea of what the problem is and is trying to tell you... having the car scanned with a good VW-specific scanner (not clear if you did this or used a generic scanner) and making note of the code(s) would be a great step as well. Searching here on whatever codes you get will help narrow things down as well.

 

[tig_21]

Awesome! Thanks for the info. I'll read through that and hopefully figure something out. I have a feeling it might be a tedious task trying to figure it out unless the scan gives something more specific.
Thanks

 

[craig01b]

Yes, a boost/maf problem, has nothing to do with cruise control. Codes need to be pulled, and a good visual inspection of all the boost vacuum lines. Good luck

 

[tig_21]

Is there a way to test for boost leaks?
The dealership I bought it from said they would fix it. I took it there and they replaced an o-ring and said it was good. Drove it on the freeway and its still bogging down like it doesn't have any power on 4th and 5th gear. But the CEL isn't on so it might be a small leak somewhere. Didn't know if I can hook up a boot and run pressure to the motor and listen for leaks anywhere...?


*Edit*
Nevermind I found this link:
http://www.myturbodiesel.com/wiki/boost-leak-tester-leaking-turbo-symptoms-how-to-fix/

 

[Vince Waldon]

A boost leak is actually one of the last reasons for limp mode... before I spent all the time building those jigs I'd be inclined to follow thru on the original troubleshooting guide.. vacuum hose inspection, testing the actuator for full range of motion, etc.

Usually when there's a large boost leak you hear it long before the engine limps, and if it's a small leak the engine compensates and *doesn't* trigger limp mode.

 

[tig_21]

I checked all the vacuum lines with a vacuum pump and they all seemed fine. I put vacuum to the actuator and nothing. This would lead me to believe its the actuator?...
The N75 valve works fine too. The dealership is supposed to get a new actuator after I told them what I thought it was. Problem is I don't think you can buy those without buying the whole turbo assembly right?...
I know at one time you could buy just the actuator but I'm not sure if its high quality or not either. What do you guys think?...

 

[rwolff]

I checked all the vacuum lines with a vacuum pump and they all seemed fine. I put vacuum to the actuator and nothing. This would lead me to believe its the actuator?...

From what you're saying, it sounds like when you put vacuum to the actuator, it holds vacuum (i.e. doesn't have a ruptured diaphragm), but the rod doesn't move. Assuming this is the case, disconnect the actuator rod from the VNT arm on the turbo and try the vacuum again. One of 2 things will happen:

- The rod won't move. You have a jammed actuator, which needs replacement.

- The rod moves, indicating it's the VNT vanes in the turbo that are jammed. Actuator is good, but you either need to free up the stuck vanes (from what I've read here, this tends to be a temporary fix) or replace the turbo.

 

[tig_21]

Sorry what I meant to say is that when I put vacuum to the actuator from the motor side port it doesn't hold vacuum. In fact I can't get any vacuum at all. I tried pushing up and down on the rod and it moves freely but still no vacuum.
I would think the diaphragm is worn out. The car runs good when it's cooler out too. But when it's hot I can't get much power, feels like limp mode....