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2000 KIA Sephia
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Discussion Starter · #1 · (Edited)
I own a Kia Sephia 2000 with about 82,000 miles on it I bought it about 6,000 miles ago.
When I got it did tune up (did not replace wires; did do plugs)....then car started misfiring, throwing codes P301 and P304 for cylinder 1 and 4. In my car I have 2 coils that run 4 cylinders. So I replaced the coil that ran 1 and 4 and never had that problem again.
Until like 2 months ago check engine light came on while I was driving on the highway throwing misfire codes for 2 and 3, engine was shaking hard.. especially when in idle... i could drive but felt like i had half the power could not fully accelerate. So i replaced that coil. It fixed the problem for now.

Then about two weeks after it started happening again so went to autozone cashed in my warranty on the coil and got a new one for cylinder 2 and 3 put it in and it worked fine, stopped knocking, was driving better, check engine went off.

Now again, it is doing it. Check engine light comes on, engine starts misfiring and shaking the car while idling, cannot accelerate fully..

:confused: What is it? Is this as simple as some bad wires? Why is 2 and 3 misfiring at the same time? Would think it is coil, but cannot possibly be... Is it the plugs? should i look at those?

I have been reading the forums about this and always see troubleshooting in this order...
wires, plugs, coils, compression tests, (fuel filters?)

Tomorrow I will go to the store and pick up some wires since they are so inexpensive but I do not think this will change anything.. just a hunch..

Please, any advice would be appreciated...

* also every time I start it up it gives me a hard time, has been happening as long as i can remember but it always starts up...alternator went once so I replaced that... but besides that... it takes a few seconds to start when i turn the key makes struggling noises then starts up (do not know if this is related to anything)

Premium Member
2015 Buick Verano "Leather Group", 2015 Kia Optima Hybrid
6,092 Posts
What did you gap the plugs too? .044 like the parts stores state?
That is NOT RIGHT.

You need to regap them, yes the plugs say PREGAPPED, but they are gapped to .044, you need them at .028-.033.
This will solve your misfire.
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