I have 08 cobalt ss, honestly it had been my dream car ever since I was first introduced to it, after yrs of struggle into finding and finally getting one it has made my whole entire dream a waste of it, I have had this car I bought in April of this yr 2014, I have had alot of problems with it first week turbo gave out, jusy out of nothing driving to class a morning there was no boost, I replaced turbo with a new ko4 from zzp, then the worst has come along all cylinders misfiring and fuel pressure ishas terriblefluctuations so I decided to take it in to dealer they changed fuel pump which included the new fuel.pressure regulator, car worked fine for about 2 weeks untill again same problem. Car was in the dealer for the past 2 months and finally got it back this week supposively problem was car was corbunated and they had taken care of it and for them.car is working fine, I will never again take it to the dealership, worst experience of waiting 2 whole months for them to come up with a stupid conclusion that has not solved the problem, I am now tired I have no car to drive,
If any one can help me out I would appreciate it,
Sorry if grammer is wrong on the phrases above, any help is appreciated thanks,

 

What area in south texas are you from?

 

Laredo, tx

 

U most likely have coked valves that need cleaning or u need new fuel injector seals.

 

This would be the problem?, how do I get to the injectors if there direct injection?

 

take off intake manifold, fuel rail and injectors are located under there, then its just take off 4 bolts and pull them out. good thing is while intake manifold is off u can clean the valves. there is a how to in the how to section. its pretty easy. ced has injector seal kit, but u will also need a tool to install those. in my case I just upgraded to the bigger injectors from zzp. rail and injectors for 350 bucks. but u need to get tuned for them after. if u have a boroscope u can go in through the brake booster line hookup in the intake manifold and check out the valves before u do anything. if they are badly coked in gunk, that's most likely ur issue. direct injection cars have no gas hitting the valves so they get gunked up. need powell oil separator (similar to oil catch can, but actually works) to keep oil from gunking up ur valves after they are cleaned.

 

but if u are getting a machine gun sound when u go into boost with the misfire, its definitely ur injectors. same thing happened with me on one cylinder. just need new seals. if u still under warranty. go tell them to change the seals.

 

I will check that out, the guys from the dealership supposively added an additive to help clean up the gunk,
Also spark plugs have been changed twice since they end up very badly carbonized, turn black real quick, and I dont get the machine gun sound

 

Where exactly did they add the additive? Into the gas? Cause lol if they did, the gas doesn't touch the valves. If seafoamed it that won't do anything either, u have to take off intake manifold and walnut blast the valves. There isn't a quick way around this issue by just adding an additive, it has to be done right or it won't fix anything.