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Discussion Starter · #1 ·
On way home check engine light came on. Got home and hooked up code reader and got the P0302. Just replaced spark plugs a couple weeks ago. Also a new AEM air filter installed also.When giving it gas it was sluggish at times. But when I took foot off gas pedal check engine light went off. Foot back on and check engine light back on. Car has 104,777 miles on it. Would replacing just coil pack fix issue.
 

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2021 Kia Forte GT-Line
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Was the check engine light on solid or was it flashing? And did you use a scanner to get codes. If it's a misfire the code will tell which cylinder to look at.
 

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Discussion Starter · #6 ·
Is the correct firing order 1,2,3,4 (left to right while looking at engine). Pull number 2 and the gap went from .044 to .050. Only code was P0302 and there was no pending codes.
 

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Discussion Starter · #11 ·
Well I'm going to just change the spark plugs from NGK to BOSCH tomorrow. Will update once done and drove around some.
 

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2017 Kia Forte LX
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Swap the #3 coil with the #2 coil and see if the misfire moves to cylinder #3. That same thing happened to my 2017 Forte LX and it was the coil. Mine happened at 108,000 miles, so that's pretty close to yours. I had changed my plugs at 100,000 miles per the owners manual. Strange thing was that all of the OEM plugs had a gap of .035 when I removed them and everything I could find said to gap the plugs to .044. I did that and haven't noticed any difference in performance or mpg.
 

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Discussion Starter · #13 · (Edited)
Well switched the 2 and 3 coil pack and misfire still there. Hooked up code reader and I noticed two codes this time but. Also have a P0303 too. So. I will first try new plugs. Then if no change. Will change coil packs next.
 

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Well switched the 2 and 3 coil pack and no chane. Hooked up code reader and I noticed two codes this time but. Also have a P0303 too. ..
Sure seems like a change to me, and I'd have no reason to replace plugs after seeing that happen. But as always, your vehicle, your choice.
 

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Discussion Starter · #17 ·
Well I put coil pack from cylinder 2 on 1 and 1 on 2. Then put 4 on 3 and 3 on 4. Still misfires and now have 3 misfires. P0301, P0302 & P0303. Put coil packs back to original spots and same results. Guess tomorrow I will have 4 misfires then.
 

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Well I put coil pack from cylinder 2 on 1 and 1 on 2. Then put 4 on 3 and 3 on 4. Still misfires and now have 3 misfires. P0301, P0302 & P0303. Put coil packs back to original spots and same results. Guess tomorrow I will have 4 misfires then.
Assuming that you've been erasing codes and there are not old ones still hanging around, then I'll ask what type of codes are showing up. There are active, pending, and permanent OBD code types. Emission-related codes get corresponding permanent codes set, which can't be erased with a scan tool. So I'm asking if some of these misfire codes are listed as being permanent codes, but there is no matching active misfire code for those cylinders. If you only have one active misfire code and the rest of them are only permanent ones, then that would again be indicating that the code is following a single bad coil pack.

But if these are all active, concurrent misfire codes, then perhaps the ignition condenser is going bad.
 

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2021 Kia Forte GT-Line
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Well I put coil pack from cylinder 2 on 1 and 1 on 2. Then put 4 on 3 and 3 on 4. Still misfires and now have 3 misfires. P0301, P0302 & P0303. Put coil packs back to original spots and same results. Guess tomorrow I will have 4 misfires then.
Yeah the coil that started in 2 is bad. Now you need to figure out where it is and replace it.
 

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Discussion Starter · #20 ·
Assuming that you've been erasing codes and there are not old ones still hanging around, then I'll ask what type of codes are showing up. There are active, pending, and permanent OBD code types. Emission-related codes get corresponding permanent codes set, which can't be erased with a scan tool. So I'm asking if some of these misfire codes are listed as being permanent codes, but there is no matching active misfire code for those cylinders. If you only have one active misfire code and the rest of them are only permanent ones, then that would again be indicating that the code is following a single bad coil pack.

But if these are all active, concurrent misfire codes, then perhaps the ignition condenser is going bad.
My bad. I forgot to clear codes. Will do that and redo what I did.
 
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