POSSIBLE Engine Misfire. Tiny OR BIG Problem?

I looked over the other posts for 'POSSIBLE misfires', but I don't see my issue. So...I THINK my 2006 Aveo is misfiring on the morning cold star only. Never any other time. I have never had this problem with any other car in my life, so I cant compare it to anything. That damn 'check engine' light came on, 'flashing' a few days ago. Not steady,but flashing. So that means a misfire or Cat. problem...right:confused:

I drove to work, a 10 min drive. I came back 4 hrs. later, it was still slightly warm, it started right up and ran fine all day. The light was gone, flashing or otherwise. Still gone now, 4 days later. Has not come on again, flashing or steady.
The engine starts fine, revs up on the cold morning start, then calms down, we all know the cycle. BUT it runs rough for just the first 2-3 mins. the morning cold start only. Then it is smooth as glass, as usual. (Trying not to babble).

So...what can I check on my own? I put in new Iridium plugs 6 months ago, took out the Bosch Platinums. Changed the oil on Jan 1st. like a good car owner:D. I use the same gas from the same station, and a tank-full takes about 3-4 weeks to get to empty. The 'flashing' check engine light is gone, the rough idle stops after 2-3 mins, the temp gauge is barely above stone cold, then it runs smooth. No smoke out the back, no leaks, everything else seems fine. I have a new ACC. belt on the engine, new head gasket, for a minor oil 'weaping' around the spark plug area, that gasket. That was 5 months ago. Don't know if any of that matters.

So what else can I check or change, or clean on my own?? To see if it is anything else causing this issue. Before I try to find money to go to a mechanic. Is this 2 min. 'possible misfiring' damaging the engine? OR am I just wasting gas? I can live with that. No big deal to me!! Fla. has no inspection for tail pipe emissions.:hello1:.So if it is just wasting a few drops of gas, I don't care. BUT is it causing damage to the engine? Any ideas??? Thanks for any help.

Pull the plugs and see if there is any oil on them; valve cover gaskets going bad seem to be a problem with these cars

That is the gasket I mentioned that I had replaced months ago. The VERY minor leak it had is gone.
Thank you for the idea, but that is long ago fixed, and I cleaned out the little bit of oil in the 1 spark plug chamber that had some. When I put in the new Iridium plugs.

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Originally Posted by FlaAveo5

I looked over the other posts for 'POSSIBLE misfires', but I don't see my issue. So...I THINK my 2006 Aveo is misfiring on the morning cold star only. Never any other time. I have never had this problem with any other car in my life, so I cant compare it to anything. That damn 'check engine' light came on, 'flashing' a few days ago. Not steady,but flashing. So that means a misfire or Cat. problem...right:confused:

I drove to work, a 10 min drive. I came back 4 hrs. later, it was still slightly warm, it started right up and ran fine all day. The light was gone, flashing or otherwise. Still gone now, 4 days later. Has not come on again, flashing or steady.
The engine starts fine, revs up on the cold morning start, then calms down, we all know the cycle. BUT it runs rough for just the first 2-3 mins. the morning cold start only. Then it is smooth as glass, as usual. (Trying not to babble).

So...what can I check on my own? I put in new Iridium plugs 6 months ago, took out the Bosch Platinums. Changed the oil on Jan 1st. like a good car owner:D. I use the same gas from the same station, and a tank-full takes about 3-4 weeks to get to empty. The 'flashing' check engine light is gone, the rough idle stops after 2-3 mins, the temp gauge is barely above stone cold, then it runs smooth. No smoke out the back, no leaks, everything else seems fine. I have a new ACC. belt on the engine, new head gasket, for a minor oil 'weaping' around the spark plug area, that gasket. That was 5 months ago. Don't know if any of that matters.

So what else can I check or change, or clean on my own?? To see if it is anything else causing this issue. Before I try to find money to go to a mechanic. Is this 2 min. 'possible misfiring' damaging the engine? OR am I just wasting gas? I can live with that. No big deal to me!! Fla. has no inspection for tail pipe emissions.:hello1:.So if it is just wasting a few drops of gas, I don't care. BUT is it causing damage to the engine? Any ideas??? Thanks for any help.

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Just because you replaced something recently doesnt mean its actually working 100%. You might not visibly observe any leaks and/or smoke, but that doesnt mean its leaking internatlly and fouling your plugs. It takes less than 10min to pull the plugs, inspect, and reinstall.

i have all clean and fine.

If it only runs rough on a cold start good basic things to do is to clean your throttle body and idle air control vlave, it may also help to have your injectors cleaned as they are getting older.

I am having similar issues with my 2005 5 speed manual, and my check engine light is on steady for random multiple misfire code, and I have noticed that when I come to a red light, and knock my gearshift into neutral, my idle speed stays up high for a while, and this also correlates to reduced fuel mileage. I am planning to replace both O2 sensors today, and I will let you know after I have drove the car for some time if this fixes the problem or not.

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Originally Posted by Hoosiertrucker

I am having similar issues with my 2005 5 speed manual, and my check engine light is on steady for random multiple misfire code, and I have noticed that when I come to a red light, and knock my gearshift into neutral, my idle speed stays up high for a while, and this also correlates to reduced fuel mileage. I am planning to replace both O2 sensors today, and I will let you know after I have drove the car for some time if this fixes the problem or not.

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I would like to know your outcome. As for my Aveo. It SEEMS like it was a bad tank of gas. The 'misfire' or whatever was/is, is almost totally gone. No engine codes still, and no 'flashing service engine light', only that one time, still has never happened again.
About to fill up from a different gas station, and see if it brings on any codes with a FULL tank. Was going to try premium gas, for the very first time, now that gas is SO cheap,at least here in Ft.laud. And se if that makes any difference.

I know this is late....but. I ALWAYS fill my tank to the VERY VERY TOP. Since the first day i bought the car. Yes...past the auto cut-off from the pump. Not going to do that from now on. BUT maybe that gas vapor canister has/had gas in it??? Could that cause it?? Does 'liquid' fuel in that canister eventually dry up or turn to vapor???

Bad gas hehe that reminds me of a lot of funny jokes :) Anyways can't say I know but there could have been a chance that it was bad gas and that could cause knocking and throw some codes. Gas is very cheap here for a small amount of time I assume. If accidentally there was diesel put into the wrong mix it could cause bad gas, but thaat never happens of course.

Oh I forgot to mention that my check engine light flashed on a bad misfire one day. It was the plugs in my case.