# Symptoms/Indication of bad PCV?



## Josh Sp (Aug 16, 2010)

**Repost from MKV Forum**

All right, to start off this thread is somewhat of a spinoff of another recent thread:

http://forums.vwvortex.com/showthrea...e-when-driving

To summarize, I experience a surging/bucking while driving when it is snowing. Generally around 50-60 mph, steady throttle, I experience short, violent surges/bucks and then back to normal. Seems to be worse when it's snowing more heavily. Never have received a CEL from it. In the previous thread, someone suggested it's a bad PCV.

Now, I have several questions. I only have a very rudimentary understanding of what the PCV is/does. Can anyone explain to me why these conditions would result in these symptoms if it is indeed the PCV that is the culprit? Also, can this surging/bucking cause serious permanent damage if I proceed the way it is?

And lastly, I'd like suggestions/input on the best PCV fix out there. Searches I've done haven't really resulted in a clear-cut best option. I found mixed results about whether or not the most recent revision of the OEM parts are a permanent fix. That leaves the BSH revamp or a catch can. The revamp seems to be a fairly simple fix, but some people seem to not like them. And lastly I'm kind of hesitant about a catch can because I've read that they can be fairly maintenance intensive and aren't always cold weather friendly.

Sorry for being so long winded, I appreciate any and all constructive information any of you can provide and thanks in advance!


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## Kelion (Apr 2, 2011)

I've read in threads(can't find exact link at moment maybe on golfmkv.com) that says with car running, pull dipstick, if the idle turns rough, its fine, if it stays same, not fine. Most people say catch can is way to go, I hate the idea of the maintenance and have contacted a company to build an AOS, you read my thread in the link below where I go into more detail about why it is better than a CC. I personally don't have a CC or PCV fix because I'm hoping Crawford Performance will develop an AOS for our engines. Anyway hope this helps, if I find the link tomorrow, I'll post that up here as well.

http://forums.vwvortex.com/showthread.php?5597703-Alternative-to-Catch-Can!!

I've got some pretty good info on the AOS here as well as links to Crawford and a link to how Crawford's works, etc.

Also Crawford AOS is the best solution for winter conditions.


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## ROH ECHT (Dec 9, 2010)

The pcv or positive crankcase ventilation takes gases/vapors from the crankcase that would contaminate the oil and recirculates it back into the intake to be burned rather than just releasing them straight into the atmosphere. It has a spring loaded diaphragm in it on ours which tears or the valve to cover seal leaks causing problems with the engine harmony. I have a BSH stage 1 pcv fix that eliminates the oem diaphragm but doesn't prevent its function. It is simple and it works. A catch-can is a system placed between the pcv valve or fix location and the intake return port. It is designed to trap residue from those gases/vapors preventing them from further traveling through the intake system. There is a rear crankcase tube and check valve that aids in bringing those gases/vapors up to the valve and it has failed occasionally as well. I've replaced mine once, and some have been removing the check valve inside of that tube. 
I believe Eurojets system does not remove the oem diaphragm but aids in preventing its failure by adding another check valve to the existing system.
I've had no issues since adding my stage 1 pcv fix, but I also clean my intake valves every 10k miles with the 3m cleaning stuff to slow down valve build-up. A catch-can system will slow intake valve build-up as well as give you pcv issue relief but costs more initially. 

Hope this helps you decide


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## dmorrow (Jun 9, 2000)

I had a similar issue, not sure if it is the same.

http://forums.vwvortex.com/showthread.php?5152319-Misfires-only-when-it-is-snowing

I replaced the engine cover because of a crack but with almost no snow this year and not driving to Ontario or Michigan as much I don't really know if it solvd the problem.


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## Josh Sp (Aug 16, 2010)

ROH ECHT said:


> The pcv or positive crankcase ventilation takes gases/vapors from the crankcase that would contaminate the oil and recirculates it back into the intake to be burned rather than just releasing them straight into the atmosphere. It has a spring loaded diaphragm in it on ours which tears or the valve to cover seal leaks causing problems with the engine harmony. I have a BSH stage 1 pcv fix that eliminates the oem diaphragm but doesn't prevent its function. It is simple and it works. A catch-can is a system placed between the pcv valve or fix location and the intake return port. It is designed to trap residue from those gases/vapors preventing them from further traveling through the intake system. There is a rear crankcase tube and check valve that aids in bringing those gases/vapors up to the valve and it has failed occasionally as well. I've replaced mine once, and some have been removing the check valve inside of that tube.
> I believe Eurojets system does not remove the oem diaphragm but aids in preventing its failure by adding another check valve to the existing system.
> I've had no issues since adding my stage 1 pcv fix, but I also clean my intake valves every 10k miles with the 3m cleaning stuff to slow down valve build-up. A catch-can system will slow intake valve build-up as well as give you pcv issue relief but costs more initially.
> 
> Hope this helps you decide


Thanks! Is there any way you could tell me how a leak in the PCV mixed with snow would cause this jerking?


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## Josh Sp (Aug 16, 2010)

dmorrow said:


> I had a similar issue, not sure if it is the same.
> 
> http://forums.vwvortex.com/showthread.php?5152319-Misfires-only-when-it-is-snowing
> 
> I replaced the engine cover because of a crack but with almost no snow this year and not driving to Ontario or Michigan as much I don't really know if it solvd the problem.


I suspected something similar myself, so I took the cover off and inspected it and replaced the air filter. Everything seems to be solid with no cracks/leaks. Maybe I'll try that plastic bag trick you used to isolate the problem.


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## dmorrow (Jun 9, 2000)

Josh Sp said:


> I suspected something similar myself, so I took the cover off and inspected it and replaced the air filter. Everything seems to be solid with no cracks/leaks. Maybe I'll try that plastic bag trick you used to isolate the problem.


I will be driving to Ontario next week and if the weather is bad maybe I will find out if it is really fixed. The thought with the cracked cover was the engine may have been sucking cold wet air directly into the top of the engine after the MAF. For me rain never made any difference it was only heavy snow or light snow and behind a big truck.


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## ROH ECHT (Dec 9, 2010)

Try driving around with no dipstick in its place to simulate a crack/leak. 

I don't know if snow or the cold would be the culprit here.


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## rickjaguar (Apr 23, 2009)

if this issue only occurs during snow have you considered that it might be ESP related? 


Sent from my 1st generation Motorola brick using Tapatalk


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## Josh Sp (Aug 16, 2010)

rickjaguar said:


> if this issue only occurs during snow have you considered that it might be ESP related?
> 
> 
> Sent from my 1st generation Motorola brick using Tapatalk


Definitely not ESP related; I've experienced it with dry roads when it was just starting to flurry.


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## Hogcrewer (Oct 8, 2007)

I would have the same problem with my GLI. Seemed when ever it would snow or a good mist from rain while I was driving behind someone the car would jerk. Check engine light never came on though. It acted like it was getting unmeasured air from some other place. 
Never did figure out how or why it was happening. I took the air filter out and replaced it. Made sure I had a good seal everyplace.

A couple of months ago I bought a aftermarket(typhoon-K&N) CAI. The problem disappeared.
My personal opinion is that I was getting unmeasured air or water/snow in the intake. I kept all of my old intake manifold parts. I need to examine them real close to see if I had any crack.

Not sure if this helps, but my problem went away. Living up here in AK, we get alot of snow. It was a PIA.


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## dmorrow (Jun 9, 2000)

dmorrow said:


> I will be driving to Ontario next week and if the weather is bad maybe I will find out if it is really fixed. The thought with the cracked cover was the engine may have been sucking cold wet air directly into the top of the engine after the MAF. For me rain never made any difference it was only heavy snow or light snow and behind a big truck.


I did run into a lot of snow for about an hour and a half in Ontario yesterday and had no problems. Wasn't accumulating on the road but was heavy enough to make visibility limited. For me it seems to have been the cracked cover causing the problem. Last winter every time I was in anything above a light snow I had to deal with misfires.


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