2007 cobalt ss/sc stage 2 with 2.90 pulley, full exhaust 200 cell cat, and hptune. Does that only on a cold start when it's been sitting for awhile. Smells like straight up Gas when it does it too. Occasional P0300 and I did get a TPS sensor voltage corallation once and an egr code once P0443. Any ideas? Car seems to missfire somewhat during normal driving. TB has been cleaned, maf was sprayed with maf cleaner, car has been seamfoamed.

 

2.9 is too small for 42's in my experience with HPT.

Does this all go away when it warms up? If not I'd start with a compression/leakdown test...

 

Yeah car runs perfect after 90*F coolant. It's really weird. Compression is good. Haven't done a leak down yet. Probably should. Occasional missfires if I granny shift it.

 

Id start with those trouble codes and go from there.

 

The video didn't work because it said it's private.
But a few things,
I ran a 2.85" on 42s for a while with no problems. I'm on 60s now though.

But anyways,

There was a special policy about this, it sounds like you may have a cracked fuelpump housing. It happens more in warmer climates, and I had it happen to mine. They fixed it at the dealership for free. The fuel system was loosing it's prime, and so it would have to re-prime the engine to get it to start. Check your fuel pressure and then turn the car off and see how fast it bleeds off pressure. Also check for a fuel leak under the rear end of your car.

Do you have interceptors? My interceptors would trigger an erronious P0300 on my car. ZZP deleted it in the tune a little while later.

I have no idea how you got this code. Our cars don't have an EGR system.

 

I have an interceptor yes. I literally said wtf out loud when I saw the egr code. I have a huge Crack in my header just found that. Could that be my issue?

 

Possibly, it doesn't help.

Could be an EVAP solenoid failing, don't know if that would set an EGR code but it could explain the funky running and fuel smell. Also the fuel pressure dropping due to a cracked pump but that shouldn't ever go away.

How do the plugs look?

 

Interceptors were causing me to get a false P0300 until ZZP Deleted it.

Cracked header? Maybe?? I don't see how though. You should def get that fixed!

Oh you could have some fun, Go to Autozone, let them pull the codes, and let them try to sell you an EGR valve, and then go and watch them try to look one up lol

 

Hahaha. Replaced the plugs and maf with oem parts. Still no luck. Unplugged the evap solenoid still no luck. Bad map sensor is the only thing I can think of.

 

I am getting random p0300 on my 06 LSJ, 2.9, 60s, and fully bolt ons.
I am thinking it is the plugs, have you changed yours?

 

random misfire from the P0300 code could be anything. I just replaced fuel filter after 100k and the code cleared and I have not had a misfire code yet. I'd check the simplest things like fuel filter, vacuum leaks, injectors (fuel pressure). Eliminate the small things.

 

I'm confident its your map sensor if not then faulty maf..