I have an 09 SS Turbo and it is freaking me out a little on start-up. I'm new to cars and the Cobalt is my first project car, so forgive me if I sound like a noob. I've almost had this problem randomly for the two years I've owned this car pre & post Mods. It is stock tuned with minimal bolt on mods installed. I have a K&N Typhoon Air Intake, Hahn Cat'd down-pipe, and Injen Inter-cooler Charge Piping. Currently I have about 17,000 miles on the car.

As far as the problem goes, each morning when I start it, while I sit in my seat you can feel the car shake a little bit and see the RPMs vary up and down and up and down, and eventually it levels off and idle's normally. While driving, it doesn't seem to misfire at all as I feel no loss in power or acceleration, but since I haven't dyno'd it, I don't know if there is a misfire spike or not. Once it starts first in the morning, the starts afterwards don't seem to have the same issues.

I took it in about a year ago and they supposedly cleaned the carbon off the engine and said they replaced the coils, spark plugs, and packs and i'm still having the issue. I have two months left on the warranty and am worried that something is going to ruin the car and if I keep it eventually I will have to dump tons of money into repairs, but the dealership seems to be clueless or says they can't replicate it.

Things I've Tried:
*I've tried rotating the metal fin on the K&N Filter at 11, 12, 1230 with no luck
*Disconnected the battery for more than 15 minutes while I cleaned the MAF Sensor
*Sea-fomed the car yesterday (will be replacing the spark plugs today, gapped at .43)

This morning it threw the code again. Any help would be much appreciated!

 

I'd just take it into the dealership for warranty and tell them you don't want the car back until it's fixed.

What code is it throwing? Just a random misfire code? Do you put premium in it like it's supposed to have?

 

.43 is not a good spark plug gap.

Also, put it back to stock before taking it to the dealer. The intake won't cause any problems but the dealership may try to give you a hard time about it.

 

Yes, it's almost always a random misfire and it's never the same cylinder all the time, sometimes it's multiple. I always run 91 Premium gas yes, I've never put in anything less.

 

I had this exact same problem. I had to go buy new spark plug's gapped at .032 and it fixed the issue.

 

That would be fantastic if that's all it was. For the spark plugs, I went to O'Riellys Auto Parts, gave them my model number and they gave me NGK's OEM pre-gapped Spark Plugs at .043. I wonder if they have any at .032. Or is there a good place? What Sparks is everyone running and where did you get them? Thanks so much.

 

This is all my local shop had in stock, they appear to be .036 (Maybe for altitude since I'm in the mountains in Utah), they didn't have any iridium ones. What makes iridium better?

NGK G-Power Platinum 5019 - Spark Plug | O'Reilly Auto Parts

Will these work OK do you think? I can swap them out tonight and test them for the next few days.

 

You are not tuned for the intake. Do you have any way to log your fuel trims?

 

I'm at 5800 feet. I just gapped mine using a spark plug gapper. The ones i bought were set to .035

 

So my mechanic friend and I pulled out the plugs to replace them tonight. They aren't discolored at all and the white is almost as white as the new ones I purchased. So my buddy said that I must be running lean since it's the stock map. He suggested that there is nothing wrong with the car itself, but the stock map is causing it to run lean and I just need to get it tuned to add more fuel. What is weird, is the K&N is supposed to be designed so you can use it without a tune from what I understand. Any thoughts? Or is he spot on?

We decided to just throw the old plugs (AC DELCO) back in, but we adjusted them from .036 to .032 since everyone on here is somewhat in agreement that .032 is the most commonly used gap. I doubt it will fix my problem, but I'm a little weary to drive my car much as I've heard if you run lean for too long it can cause things to get way too hot. This is all new to me though, so what do you guys think?

 

wow that gap is bad, .032 is what u want

 

Do you still have your stock intake? You could always try putting that back on until you can get tuned.

 

This

 

Yes, I still have all of my original parts. I'm going to try to find out if I can get it tuned within the next week or two, and if not I'll throw the stock intake back on for the time being I think.

My question is, how come from Autozone or O'Reillys they have spark plugs "Stock Gapped" at .036 & .043 and told me at the desk it's not a good idea to adjust those, when GM recommends a gap between .032-.035? Until now, I certainly didn't know how to or why to gap them, it's just interesting to me. Anyways, thanks for your help you guys. It's a relief knowing my car isn't going to blow up!

 

The plugs may be used in another vehicle that requires a different gap OEM. I don't know this, but that would be my guess.
Well unless I'm wrong the car runs rich on start-up. Anyone?
I also have a K&N intake. Just in the last two days I searched a bunch of threads about the filter position. Then I played around with it myself. I had a lean condition. In my research and playing around with it myself I found this. The metal rib on the filter.... Rotate the filter so that metal rib points straight up. Right up towards the sky. At least in the 11:30-12:30 position. That helped me out a ton. Now if I jab the gas it spikes rich for a moment and settles. Much better than lean.

In your case I'm really thinking spark plug gap. Let us know!
I bought stockers from ZZP and they were gapped at .030. Then I bought the NGK 3787's from Amazon and they were also .030. I put mine at .034 but .032 is good too. I don't have any misfire issues at .034 so I just keep them there. Better to go as wide as you can without causing issues.