hi my cobalt is running really bad when i accelrate it stutters alot when i give it say half throttle, i feel like the boost isnt climbling like it should be at lightish throttle. but its fine if i downshift from third to second and floor it no problems until i hit third gear then it will stutter. i have hahn catless downpipe, zzp canned tune 22 lbs of boost, gmsi map sensors(tuned) injen cold air intake( tuned) ingen upper charge piping. car idles fine and can be driven normally with no trouble. the list of codes i got are

P0089
Fuel Pressure Regulator Performance
ECM

P0627
Fuel Pump Relay Control Circuit
ECM

P0300
Engine Misfire Detected

P0301
Cylinder 1 Misfire Detected

P0302
Cylinder 2 Misfire Detected

P0451
Fuel Tank Pressure (FTP) Sensor Performance
ECM

i have cleaned maf sensor and replaced it.
i have got the fuel system cleaned by GM valves throttlebody etc

if anybody can help me out id very much appreciate it!

 

i have replaced all coil packs and spark plugs also

 

I'd start with the canned tune. zzp isn't bad at tuning, but every car is different so a canned tune is only "so safe". Look into finding someone that can do a custom tune for you. Might also do a compression test just to make sure there's no internal damage. sounds like you already did plugs and coils.

 

both cylinders misfired 22 times when this happens was logged form gm scanner

this occured before the tune, i thought it would have fixed it lol

 

I would still definitely recommend getting a custom tune. not to mention during the custom tuning process (datalogging) they can monitor all sorts of things going on.

 

Never tune your car if if has issues. Fix it first.

 

no doubt i will eventually know one around me tunes. it feels like its not getting much fuel idk its really weird

 

Sounds like the sock in your fuel tank is gummed up, check for any signs of fuel leakage at the hpfp. Not an easily diagnosable issue over the net. I can tell you that suggesting a custom tune to fix a mechanical issue is a good way to **** off your tuner.

 

oh yea forgot to mention car is running really rich and smells like gass, and it backfires so much its not normal. it back fires at low rpms everytime, even switching gears

 

could it be a clogged fuel filter??

 

There isn't one on these cars. Gunky valves or cracked piston.