hey I'm new here and I just bought a chevy cobalt ss supercharged with a stage 3 kit on it like 2 weeks ago. It's been ok until yesterday. When i left work and startwd driving it started shaking as I was shifting gears and my check engine light started blinking. So I ran a diagnostic on it and these are the codes it is reading...p0300 p0446 p0128. Can someone please tell me exactly what I need to buy and replace to get it running good again? Or give me any tips. Id greatly appreciate it. Thanks,
Lauren

 

Please tell me you got a CarFax or Used Vehicle Information Kit before you bought the car. Stage 3 = modified, so did you even test the car out?
Anyways Google is your best friend, and you should get to know it well with a modified car.
- P0300 Random Misfire Detected Code
- P0446 Evaporative Emission Control System Vent Control Circuit
- P0218 Transmission Over Temperature

Got these from obd-codes.com

Check: Spark plugs, coolant levels (and condition) first.

 

Welcome! Starting with P0446, it could be the under hood EVAP purge solenoid being stuck open and causing a vacuum leak. A simple test would be to remove the solenoid and attempt to blow air through it. If you are able to blow through it, then it has likely failed open and could be the cause of the random misfire code, P0300.

 

^agreed, check and see if you can blow or suck through the purge valve in both directions. You shouldn't be able to when its off the car. The p0128 is a thermostat code that basically means the engine is not getting up to operating temperature fast enough. That is usually caused by a bad/sticking thermostat, very common in these cars.

 

Well no I didn't get a car fax on it and and to be honest I'm pretty sure the dude lied about the stage 3 kit. But yes I did check the car out as far as looking under the Hood to make sure that the oil was changed, I test drove it, had someone else take a quick look at it also and they said everything seemed to be good. When I bought the car the check engine light was not on. After I test drove the car the guy proceeded to tell me that the car only ran on 93 grade gas, so after I bought the car and went to the gas station to put 93 gas in it I shut the car off and put the gas in it and then when I went to turn it back on it was turning over but acted like it wasn't getting power from somewhere which I knew something wasn't right. The car finally started and I called my friend and gave him the rundown on what just happened and he told me that it could possibly be the gas cap not being on tight enough and are getting in the fuel system , a friend of his had a problem with the same car doing the same thing so I checked the gas cap and it was on as tight as it would go so when I got the car home I checked it out a little further considering I was at my own house and not in a public place where I bought the car and as you all know the batteries in the trunk so when I check the battery out the cable came straight off of it. So in other words dude did not tighten the bolt back and he obviously had a system in the car because there was a wiring harness for a system and one of my cables that he had screwed onto the battery, I'm not sure which cable exactly that it was but it wasn't the positive or negative cable but I do know that the bolt was stripped out so I went and bought new battery terminals and put them on and I'm going to buy a new battery also just to be on the safe side on my part. I really regret buying the car especially with no Carfax on it because my dad said anytime you put a stage anything on a car you have to modify it with the computer and there's no telling what the guy did I'm just not sure he even knew what he was talking about whenever he was telling me all about the car !!! Sounded good, and I just really needed something to be able to get me back and forth to work so I was able to buy my kids something for Christmas. Me and my mom had been arguing about me using her vehicle to get back and forth so I saved every little penny that I could for about a month or two and I found this and apparently made a mistake by making a hasty decision. Now I am a female and I do know a lot of things about a car to be a female but I don't know everything. I love to learn about them. it's pretty much always been a dream of mine to go to college to learn everything and possibly open up my own shop. It's something I would love to exceed in in my career in the near future. But anyways, So what I did today was I had my dad clear all the codes off of the car, after that I cranked it back up, and I accelerated to 3000 RPMs and then the check engine light came back on and started blinking so I turn the car off again plug the diagnostic in Ran another test on it and the only code it showed this time was the P0300 code. I am now online looking for the cheapest ignition coil packs for my car (with a 1year warranty on them) as well as spark plugs and I am going to change the spark plugs first see if there's a difference if not I'm going to replace all ignition coil packs instead of trying to figure out which one it is. Am I doing the right thing by what I just told you guys? And thanks for all of your help by the way I greatly appreciate it to the fullest extent. I was seriously about to lose it not knowing what could possibly be wrong and with me having three kids and Christmas around the corner and all three of my kids having birthdays in January February and April I was freaking out but this seems to be an easy fix.

 

Sorry I forgot to ask this question in my other reply, so how can I tell if there was ever a stage 3 kit put on this car? The easiest way for me to find out would be ideal. Thanks again guys

 

Welcome, and just a point of reference for clarity on the forums use multiple paragraphs and/or double spacing for different statements.

Don't jump to changing the ignition coils right away, start with spark plugs. Although which plugs to buy will depend on the modifications to the car.

Take pictures of the engine bay, the pulley on the supercharger, and if you can see the fuel injectors get a picture of them as well. Users on this site can tell from that.

To find out if it is a GM Stage 3, does your AC work?

 

You should invest in alldatadiy.com to get all the factory service information. It won't solve 100% of your problems 100% of the time, but it can be very helpful such as listing all the P-codes and the diagnosis steps for each P-code!! That is handy. Not to mention you will get wiring diagrams, part locations, and sketches of parts and how they go together.