06 chevy cobalt misfire problem

Alexo86

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#1
I have an 06 chevy cobalt LS 2.2 with this misfire problem.
I was driving my car to work when I was driving up a hill I notice I start loosing power like if was running out of gas followed by a flashing check engine light so I took it back home. When I stopped it and I notice my engine was shacking like running out of gas.

What I did next is read for the code of the check engine light and showed me 2 random misfire with the P0300 code for both. After that, I change the coil booths of the spark plugs and two spark plugs aswell but my car didnt turn on anymore. Any help will be appreciated.
 

billr

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#2
Any other codes, or just the P0300?
 

Alexo86

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#3
It shows me two codes but they are both the same p0300 and I've doing some research online and so far I have found out that most of these cars deal with the same exact problem and shymptoms as mine at some point and most of the owners have stated the ECM dont last two long in this type of cars.
 

billr

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#4
Does the engine crank but not fire, or not crank at all? That seems very weird that P0300 is set as two "separate" codes. You are saying that when you go to reads codes the scanner indicates "2 codes set", then when you read particulars the first one comes up as "#1 P0300", then you scroll to next code and it is "#2 P0300"; something like that?
 
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#5
Are you saying you removed this:



And your engine won't start anymore? Sure helps to coat the inside of the boots with silicone, have to be aligned properly all four plugs inside of the boots, have to hold that coil pack at an angle to see that, then carefully straightened it out and push it down. If not, could have broken off the top of some plugs.

Son had that same misfire problem, but just after he filled the tank, his old man was along, you paid four bucks a gallon for water, same kind of misfire. Told him to toss in a can of Seafoam in the gas tank, after about a couple of days, cleared itself off.

Take what you read on the net with a grain of salt, reminds me of my son-in-law's dad, its the computer, its always the computer.

Did your misfire start after you filled up the tank? Stepdaughter was always having these problems using these cut rate gas stations to save $.02 on the gallon. Would hook up a fuel pressure tester, hot wire the fuel pump, and used that hose into a clear gas jar. Look, you have water in your gas. Well, dad, I am trying to save money.

Then when was the last time you changed your plugs or cleaned them? Still burning carbon that builds up on that center electrode insulator that shorts out the spark.
 

Alexo86

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#6
Thats rights it shows two codes exact same code for both, so I thought it was just a misfire of a bad plug or boot so I replace only the boots. So I start it and fire up fine like three times but after I couldnt fire up no more. So I change back the original boots to see if the aftermarket boots were causing this but didnt work either.

After this, I did a couple tests. First one was cranking up a few more times and then remove the spark plugs to see if theres any gas on them preventing the engine to fire up but no, they were all clean.

And second test I did was the compression test and I start from passanger side to driver side and the result I got:
#1- 190
#2- 190
#3- 205
#4-200
 

Alexo86

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#7
I checked spark plugs and replaced them not so long ago, so they're still in good conditions and thats why Im confused on these two codes, meanwhile I cant fire up my car, it does crank but not start.
 

billr

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#8
Does it spark at the plugs as you crank? A good quick test is to spray carb-cleaner into the intake as you try to start it. If it fires and runs like that, even briefly, it's likely spark is OK and we can focus on the fuel system.
 

Alexo86

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#9
I didnt pay attention to that, I'll test it and see what it does. Is there any way I can test my engine computer module (ECM)?? Or reset it?? I have a feeling that theres my problem for the symptoms I've research on the web
 
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#10
You have to lay that coil pack on its side, plugged into the vehicle, plug in four plug into the boots, wrap a bare wire on the bases of the four plugs and ground it, to see if you are getting a spark.

Then you need a fuel pressure tester, think this thing runs at 45 psi. PCM is like your home computer, can even have a black screen with messed up software. Would have to take it in and get it reflashed first, all that firmware is stored in flashram. How many miles on this thing.

Did you ever replace the battery, would only replace it with a Delco, with OBD II all the electrical has to be clean, bad connections or ground can generate many transients. Only the manufacture of that PCM has the proper equipment to test it, quite complicated. Then all those electrical connections.



New one is not as bad as some, around 173 bucks.
 

kev2

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#11
p0300 and p0300 - could you be reading it in 2 'files' one current the other PENDING or HISTORY?
p0300 - ignition- fuel or mechinical may cause - don;t focous on just ign.
For parts - only AC Delco or a problem- are they AC delco?
You had a FLASHING CEL? If yes I would get right into checking injectors... leakdown test- noid light ck- fuel pressure.
Finally history - vehicle STOCK? PCM is way down the list of suspects...