I am currently having some issues with my 2006 LSJ. I have done a bunch of work to it and still can’t get it to run the way it should. It cruises fine but at WOT it misses and hesitates. The car runs great when summer comes and it’s consistently 70 degrees or over. During the cold weather is when it’s at its worst. I believe that it has something to do with my PVC system underneath the valve cover. Maybe a diaphragm that is punctured or wore out. Problem is that GM discontinued all of those parts so I can’t order what I need. My only option right now is to find another engine and take the valve cover off of that and swap out the pvc systems. So if anyone has any info on this issue that could help it would be greatly appreciated

 

there is nothing in the valve cover but some baffles. the pcv system is very simple on these engines, there is a pcv valve in the intake manifold, and a fresh air hose that goes between the air intake tube and the back of the valve cover.

your running problems in cold weather are not likely to be related to the pcv. what mods do you have? has the car been tuned?

 

No I don’t have it tuned, my mods are injen cold air intake, ZZP short tube header, and a Borla exhaust. I really don’t have much done to it because I replaced so much trying to figure out this problem. New coils, new throttle body, MAF sensor, fuel pump, plugs, I replaced injector #4 because it was leaking and both O2 sensors are new, new thermostat, engine coolant temperature sensor, When my father hooked it up to the computer at the shop it threw the P0101, and the P0121 but after that I just got a P0300. After a bit of research and having the car for 2 years knowing that weather temperature is definitely a factor, I read that the diaphragm for the pcv system is underneath the valve cover and that if that diaphragm ruptures then it will cause your vehicle to run poorly during cold weather because your O2 sensors are not giving the computer the correct info for proper air/ fuel mixture

 

p0300 is random multiple misfire. maybe its not your issue but on my dads cobalt it would misfire when cold with that code. it was cylinder 1 injector all the way to the left leaking or dirty, it just took awhile for it to finally set a p0301-p0304. however you should put your stock intake back on.. its gonna buck and feel like **** til you have it tuned for that injen intake lol

 

To verify, the only code currently set is P0300? If you don't have a more serious mechanical issue I would guess your misfires are from improper fuel/air mixture. An aftermarket intake is enough to skew the MAF readings.

 

That’s the shitty part lol I don’t have a stock intake. I bought the car as is 2 years ago. I can’t really find one either GM has discontinued the stock airbox. I don’t really live in an area where someone has SS cobalt parts either or anybody that tunes for that matter. I wanted to get it tuned I just don’t know where to go get it tuned at. That was my first assumption the was the intake but I figured if it was the intake it would run like **** year round not just in the winter.