# p0171 and p0456 help needed



## cdf2.5 (Jun 5, 2012)

So i have a 2.5t stage 1 c2 kit 148,000miles. I am throwing a lean code (p0171) and a small evap leak code (p0456). So far I've found a vacuum leak, fixed it, and gotten a new oem gas cap. Yet today after letting my car sit for an hour I started it and got a cel for both of these codes. I have checked my n80 valve and i believe its operating normally. with engine off i cannot blow through the valve. With engine on at idle the valve opens and closes constantly. I believe my pcv system is ok, however with the engine off i can blow through the valve both ways. (blowing through the hose that connects to the valve cover and blowing through the hose that routes underneath the intake manifold) and when the hose is taken off the valve cover with the engine running there is no change in idle and i can see puffs of "oil smoke" coming out of the connection. 

symptoms are as follows:
- mildly rough idle
- jerky throttle response when pressing and letting off the gas pedal
- rpm surge between 1650ish and 1850ish
- small lack of power unless full throttle
- slight decrease in gas mileage ( getting about 22-24 ish mpg)
- a vacuum reading of 16-17 in hg at idle (schools vacuum gauge, i don't trust it very much). 

I have pressure tested the intake system by blocking off the intake where the air filter attaches and applying a small amount of pressure (5psi max) through an intake manifold hose.

any help would be appreciated, this is a huge annoyance.


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## mjb8482 (Mar 4, 2008)

What is your valve cover breather hooked up to? Hopefully not to the intake manifold still... Pressurizing the valve cover will destroy the valve cover seal and definitely give you a vacuum leak. 


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## cdf2.5 (Jun 5, 2012)

nonono its hooked up to the compressor side of the turbo through the intake pipe. this sort of relates to the last post i made that you commented on, i tested my n80valve to see if it would hold a vacuum. nope it was ****ed. i replaced that and it helped the lurching and i havent gotten the codes back yet, where do you have your check valves? but im still getting a 16inhg vacuum reading. :banghead::banghead: this is drivin me nuts, found some oil leaks too... on the turbo oil feed and oil return its all over my driveshaft and subframe, weird thing is im not losing any oil according to the dopstick. this **** never stops!


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## mjb8482 (Mar 4, 2008)

Oh my bad. I didn't connect the dots. Sorry about that! In my experience, vacuum leaks are hard to locate. I know I still have one somewhere because I get a high idle when hot. Reads 20 inHg when cold and 18 inHg when hot. No codes though. I totally feel your frustration. 


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## cdf2.5 (Jun 5, 2012)

mjb, where do you have your check valves for the n80 valve at and where did you get them? I found 2 collapsed hoses replaced them and went into boost it hit 9psi which is the spring i have in there and boost sloooowly started dropping all of this in 3rd gear going wot starting at about 3500rpm, idk if its related to the hoses or not, im more so thinking the n80 is opening, or its the leak i cant find.


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## mjb8482 (Mar 4, 2008)

Sure thing. Here's a link to a post where I shared all that info. Hopefully it helps. http://forums.vwvortex.com/showpost.php?p=88099400


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