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2001 Kia Sephia -Cylinder Misfire

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New User

May 17, 2007, 6:56 PM

Post #1 of 4 (5529 views)
2001 Kia Sephia -Cylinder Misfire Sign In

I have had this problem for about a year now. A year ago my check engine light went on. Code P0301 - Cylinder 1 misfire. Car has about 145,000 miles so replaced all spark plugs. Car had sat a while before a changed the spark plugs. Then ran great for about a day. Same code again thought it was spark plug wire - replaced them still having problem. Took it to someone to fix it. Same code he replaced spark plug worked great for a day or two. Same problem P0301. I just swapped cylinder 1 and 2's plug cylinder 2 misfire. About a 1 month ago it came up with knock sensor light saying it was out of range thousght this was due to spark plug mistfire? Recently I changed the spark plug again and for a day it ran fairly well still misfire every once in a while. Now it misfire all the time again. I am also getting a Gera 4 and Gear 3 incorrect ratio message. I have not been able to drive this car for almost a year now due to this problem. Can anyone help? Could it be a bad knock sensor? Bad Fuel pump? The misfire usually happen when I speed up and at idol every once in a while after I take my foot off the gas. Please Help????

Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

May 18, 2007, 5:16 AM

Post #2 of 4 (5525 views)
Re: 2001 Kia Sephia -Cylinder Misfire Sign In

The problem seems to follow that plug - new or not. Use only the plugs origninally recommended for the vehicle. Don't fool with those. If a cylinder is isolated all the time an investigation on that needs to be done.

Plugs can have problems right out of the box. They don't like being dropped either before you got them or when you install them. Any dropped plug should be looked at carefully and take note of where it went if you use it. Don't buy plugs if the box is damaged at the counter and ask for another right then.

Also: Cars don't like sitting around and if outdoors even less. If not for too long they will recover but odd things happen all over a car that hasn't been used in a long while,


steve01832 profile image

May 19, 2007, 1:35 AM

Post #3 of 4 (5522 views)
Re: 2001 Kia Sephia -Cylinder Misfire Sign In

My question is does this have the coil on plug ignition system? If it does, swap the coils and see if the misfire code follows the swap. If it does, replace the coil. If it stays on that cylinder, you should check the wiring to the coil to see if there is an intermittent open circuit. If it checks ok, disconnect the PCM and check the driver wires for corrosion, loose, or backed out pins.


New User

May 26, 2007, 2:32 PM

Post #4 of 4 (5518 views)
Re: 2001 Kia Sephia -Cylinder Misfire Sign In

It does have a coil ignition. I have since changed the Coil packs thinking it was them and still have the problem. I had one of those FUEL BOSS things on the gasoline line that leads to the cylinders. Do you thing a strong magnetic force could cause the spark plug to go bad? It still does it after removing it however maybe the plug just need to be replaced to fix the problem now?

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