Need some help tracking down an issue on Cobalt SS. This started happening 6-8 months ago, but only once every other month or once a month, just thought it was a bad fuel thing but now its happening much more often, once a week or several times a week or even a couple times in the same day recently. Typically driving highway constant speed and the engine will stutter, accelerator will be erratically providing power, try to down shift, rev engine sometimes it will come out of it, sometimes it would continue on off until I stop and re-start the car. But today sitting at a stop light it started to get eratic and it died (threw codes) and it would not start for several minutes even then it was a little hesitant.

The codes that have been thrown (not always when this happens) are P0101 sometimes but itself sometimes with P0300, 201, 302, 303, 304.

One other thing I have noticed sometimes when I have tried it, is that it seemed like the boost would not go over zero when it is acting like this. Also hear the air intake pulling then releasing, cycling ?

One thing I noticed several months ago was the engine mount on the K&N filter had come loose so the air intake may have been vibrating ? The plastic insert on the PCV valve was loose tightened that back up, not sure if the PCV valve could be causing something like this ? it was beat up and is not sealing ?

I have cleaned the MAF with MAF cleaner, I have checked the charge pipe and air intake connections, reseated/tightened.

I even took it to the dealership but they said they couldn't do anything unless it had the problem when they ran diagnostics....

It has run fine for at least 6 months since I have added any mods. Looking for anything to test, check or have checked. I had been tracking issues and have some OBD logs from a mobile app "Torque" while the issue was happening if there is something in those that could be charted/checked. The fact that it now can shut the car down has made this a lot more serious for me, than a little troubleshooting adventure.

Thanks for any help !

Current Mods on 2008 Cobalt SS:
GM stage 1 [3/2011]
K&N Typhoon Intake [3/2011]
MPX 3 Cat-Back Exhaust [3/2011]
Trifecta tune [4/2011]
MPx Downpipe with Catalytic Convertor [9/2012]
Injen Upper charge pipes [9/2012]

 

That's not your PCV valve. Your PCV valve is inside your intake manifold, between the manifold and the head, and is not serviceable.

If that vent line were loose/leaking it would cause an issue as it it would be introducing air into the system after the MAF, before the MAP. That, or any boost leak would give you the p0101 code for sure.

You're running GMS stage 1 with the crimp on connectors. I can see the exposed white wires. Check the connections where they were crimped or soldered, on both MAP sensors. I'll bet that they have weak or failing connections.

And you'll be the third one this week with the same problem.