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2008 Chevy Cobolt Cyln. #2 Misfire
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frdprefct
Novice
Apr 22, 2012, 3:01 PM
Post #1 of 12
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2008 Chevy Cobolt Cyln. #2 Misfire
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Hi All,
My first posting to the forum, so please go easy. If this is the incorrect area, please let me know and I will happily move it.
My fiance's 2008 Chevy Cobolt (2.2L) has been getting a cyln #2 misfire. I replaced the spark plugs, cleared the code, and within 2 days, it came back. I've dumped a bunch of injector cleaner, and ran the car on 94 octane just to clean things out, however, that's not helping. Searching the web, this seems to be a somewhat common problem with this car, however, there seems to be no definitive answer to the issue.
I was hoping if anyone had any ideas? My next attempt will be to replace the wires, however, I'm doubting that's the issue. The car will also experience hard startups at times, and a rough idle, though, that got much better after the plugs were replaced.
Any help would be appreciated!
Thanks!
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Hammer Time
Ultimate Carjunky
/ Moderator
Apr 22, 2012, 4:42 PM
Post #2 of 12
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Re: 2008 Chevy Cobolt Cyln. #2 Misfire
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Don't expect any "mechanic in a can" to repair anything. It won't do anything. You want to start with ignition components and a compression test before moving onto anything else. This is a COP system so you don't even have plug wires. I would replace all the plugs and the coil for #2 cylinder.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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samg.
User
Apr 22, 2012, 8:12 PM
Post #3 of 12
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Re: 2008 Chevy Cobolt Cyln. #2 Misfire
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I would swap coils, clear codes and drive it, if the miss changed to the cylinder you swapped with you've found a problem. Also have been seeing a lot of stuck exhaust valves on the newer 2.2s.
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Discretesignals
Ultimate Carjunky
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Apr 22, 2012, 8:40 PM
Post #4 of 12
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Re: 2008 Chevy Cobolt Cyln. #2 Misfire
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What is the deal with the exhaust valves? Haven't run into any of those yet.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
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samg.
User
Apr 23, 2012, 6:56 AM
Post #5 of 12
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Re: 2008 Chevy Cobolt Cyln. #2 Misfire
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Sticking/partial sticking. Have done about 5 heads on the hhrs, at least one on the g6. They'll come in for a misfire, get to the leakdown phase and of course, a nice hiss out of the tailpipe.
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frdprefct
Novice
Apr 25, 2012, 5:21 AM
Post #6 of 12
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Re: 2008 Chevy Cobolt Cyln. #2 Misfire
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Thanks for all the help guys!
I realize this isn't a one stop mechanic shop. This is the first "newer" vehicle I've ever had to really work on. I'm used to older vehicles where I can just listen to it, and figure out what's going on. With the newer vehicles being controlled by computers, and "self correcting" systems, it's hard to tell. For example, the first thing I would have replaced on this car would have been the O2 sensor based on all the information I had until I pulled the codes. All the symptoms were there, with the exception, that that computer is compensating.
Any more information would be helpful, any place to look. I don't have the tools necessary to do a compression test, unfortunately, so any hints would be appreciated.
Going to replace the coils for Cyln #2, as it seems to point in that direction from what you are telling me, and what I've read elsewhere. This seems to be a somewhat common problem with this car.
Thanks!
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frdprefct
Novice
May 6, 2012, 2:36 PM
Post #7 of 12
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Re: 2008 Chevy Cobolt Cyln. #2 Misfire
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Well, it's not the coil. Switched #2 and #4, cleared the codes, and a day and a half later, #2 started misfiring again.
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nickwarner
Veteran
/ Moderator
May 6, 2012, 3:55 PM
Post #8 of 12
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Re: 2008 Chevy Cobolt Cyln. #2 Misfire
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Try swapping injectors like you did coils and see what happens
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frdprefct
Novice
May 6, 2012, 3:57 PM
Post #9 of 12
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Re: 2008 Chevy Cobolt Cyln. #2 Misfire
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Happen to know where I get to the injectors on this car?
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Hammer Time
Ultimate Carjunky
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May 6, 2012, 4:47 PM
Post #10 of 12
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Re: 2008 Chevy Cobolt Cyln. #2 Misfire
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They are on the rail, right above the intake manifold.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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frdprefct
Novice
Jun 9, 2012, 6:35 AM
Post #11 of 12
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Re: 2008 Chevy Cobolt Cyln. #2 Misfire
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Hello,
So, I just got done swapping the #2 and #4 injector. I also cleaned them up a little. Cleared the code, etc.
Idle seemed better, drove it around the block, seemed fine. Shut it off.
10 minutes later my fiance goes to take her car out, and the engine light is on. Cyln #2 misfire again.
Cleared the code again, and waiting to see now. However, I don't suspect the fuel injector or the spark plugs now.
Thoughts?
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Discretesignals
Ultimate Carjunky
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Jun 9, 2012, 6:54 AM
Post #12 of 12
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Re: 2008 Chevy Cobolt Cyln. #2 Misfire
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Going to have to use an oscilloscope and record the waveforms for the number 2 injector voltage and primary signal to the number 2 ignition coil while the misfire is occurring to rule out a circuit or driver problem.
Beware because some of these vehicles the PCM will disable an injector if the computer determines there is a bad enough misfire.
I got a feeling your going to have to take it to a shop that has the equipment and experience to diagnose this problem to rule out any electrical problems before going inside the engine.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
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