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Awhile back my check engine light came on and I went to Auto Zone for them to read it. They told me I had a bad spark plug. Since I had 85,000 miles on original plugs I figured this was correct and I changed out the plugs and original air filter. (I change my oil every 8-10,000 miles) The check light went off for about a day and then came back on and is still on. The car runs great and idles smoothly but has started to run rough, like on 2 out of the 3 cylinders maybe, when I first start out and have to sit in traffic at a light for a bit. When this happens I shut off the car and start it right back up and it's smooth as silk again. Is this possibly something electrical, like coils, since it is remedied so quickly by just shutting off the key and then restarting? No other apparent problems except not being able to reset the wrench symbol after changing the oil (never had this problem before either). Any help would be greatly appreciated.
Brett
 

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This is a scary one!! could be electrical, could be worse!! Had this happen to my 2009 and I went the whole route changing plugs and coils only to find low compression on the cylinder.

The computer is detecting a low output from that cylinder and eventually shuts it down to protect it. when you restart the car, it tries again until it detects the low output and shuts it down again.

I would start out by checking compression on all 3 cylinders. The sparkplug thread is different than older cars and you may need an adapter , Main thing is that all 3 cylinders be close to the same amount within about 10% or so. If you see one cylinder significantly lower, then you got a problem. new plugs or coils won't make any difference.
 

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Sounds like your vehicle went into limp mode. When there is something serious, with modern car today. Even a low charged battery, or weak one. The car, will go into that mode. It will run rough, have no power. It’s a safe guard, so you won’t do serious damage to the engine. My first thought, you have a bad coil pack.That’s why you were getting a bad spark plug code.

One of my other cars, I hadn’t driven for a while. Started it up. Ran extremely rough. Would, even back up. The computer put the vehicle in limp mode. Battery must have been low. Started it back up. Ran just fine. How old, is your battery?
 

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If the OBD code was P030x then you're looking at bad valves in the affected cylinder. :)
 

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What's the OBD code you're getting? If it's a P0301 for example try swapping the cylinder 1 coil with another and see if the code follows. Could also try some marvel mystery oil in the crankcase and fuel. I think I read on here that it helped someone with lower compression in 1 cylinder.
 
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