P0171 / Valve Cover troubleshooting

[stimpy2301]

Hey folks, could use a little discussion on troubleshooting this issue.

I found previous threads here and here which sound similar to what I'm experiencing, but I haven't found a smoking gun.

What's happened: Threw a CEL the other day, P0171 (System too lean). It idles kinda rough, and about three or four separate times, while stopped at a traffic light, the TCS light inexplicably came on (but then shutoff when I started moving again).

I gave the intake hoses a quick lookover, didn't see any cracking like so many others have experienced. I inspected the valve cover, and didn't see any cracking there either, like so many others have experienced.

The only thing that seemed unusual to me was this little port (ref picture, arrow) was sucking air in like crazy. Is this normal?

Any other suggestions of where/what I should be looking for?

Thanks in advance.

 

[Stew]

You need to replace the entire valve cover. This is a common issue, the PCV valve diaphragm has ruptured and when that happens it sucks air in through that port.

That port is there to vent the backside of the diaphragm so the valve can move freely, otherwise the backside of the diaphragm would have a sealed chamber behind it and not be able to function as it's supposed to.

When the diaphragm ruptures from age, fatigue or whatever that port then becomes a vacuum leak. There's pictures of it either on this forum or cruzetalk which would help you see exactly what's going on.

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Edit: This thread has the picture I was talking about:
http://www.cruzetalk.com/forum/34-1...er-failures-cut-one-apart-see-what-fails.html

 

[Hawkdsl]

Aftermarket should look into making these with a replaceable diaphragm... and use old school metal (aluminum maybe). heat cycles will make any plastic brittle over time.

 

[stimpy2301]

Awesome, thanks for such specific info. Will verify dealership will replace under warranty. If not, looks easy enough to R&R myself, and reasonably inexpensive part.

 

[AdorableKaren]

I see the same lean code all the time. I am going for an oil change soon, I want to ask them to replace the valve cover under 100k warranty. Hopefully it fixes my problem.

 

[EzekeiL]

I had the same problem. Had it fixed at the dealer under warranty so I'd assume it would be under warranty for you as well adorablekaren.

 

[Mthomas8385]

Does anyone know if Chevy is covering the PCV system leak on the 2012 Sonic under the 100k powertrain warranty?

 

[ahtoxa]

Does anyone know if Chevy is covering the PCV system leak on the 2012 Sonic under the 100k powertrain warranty?

Yes, they are. I researched this last year when I thought this was my issue. I ended up having a cracked valve cover, which was also covered.

 

[AdorableKaren]

Does anyone know if Chevy is covering the PCV system leak on the 2012 Sonic under the 100k powertrain warranty?

Yes I believe I just had this done today covered under that same warranty.

 

[4g63gst20]

I see this is also a common issue. Mine started leaking oil, gave me a cel and was shaking a bit. They did replace it under warranty.

 

[mja]

I'm a little confused by this. I'm pretty sure the PCV diaphragm/rupture disk fails from too much pressure via the orange check valve on the actual head, connected by a passage to the intake manifold.

What else could be the problem popping these PCV diaphragms if it's not the check valve failing?

I found some info on checking the operation of the check valve on the forum, but can't find much info on replacing that orange valve... does that require replacing the head (that would be nuts)?

...I've also read there is another check valve at the turbo inlet that can be replaced... Anyone know how these check valves relate to busting the PCV diaphragm? Thanks.