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2006 Kia Sportage V6 4WD
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10 Posts
Discussion Starter #1
So going back a little while I've had some random misfires. I've had the car about two and a half years. In the first two years I think I had two instances of random misfires, spaced out, very random, no pattern. I didn't address them.

Over the winter and into the spring I was starting to see an oxygen sensor code pretty consistently. I planned on fixing it eventually. Then I started to get more misfires. Didn't know if was related or coincidental, but knowing that I'd have to take the upper intake off to get to the O2 sensor, I figured I'd change the plugs and wires too.

The misfires started to get worse. In the last two months before changing the sensor, plugs, and wires, I probably had two or three instances of pretty bad, very noticeable misfires. But it was always really random, no apparent pattern to it. And after a few minutes of running rough, it would go back to normal.

So I finally changed the sensor, plugs, and wires a few weeks ago.

Everything was good for almost a week, and sure enough misfire codes were back. They weren't noticeable the first time, but I still had P0300, P0303, P0306.

The next day I had that rough for a few minutes then back to normal thing happen.

In looking around and doing some research I noticed that cylinders 3 and 6 are hooked into the same "pack." See an image of the ignition coil here.

My thinking at first was that the coil was bad and needed replacing. But, before I got to that, I pulled off the wires and noticed that the wire for cylinder 3 wasn't seated properly, and also there was some plastic of rubber debris of some sort down in the coil. So I cleaned it up and seated it properly. Ran fine for several days.

Two nights ago it started misfiring again. Last night I changed the coil. Ran fine for a few hours and then misfired again.

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So at this point I've changed the plugs, wires, and coil. The plugs and wires were due to be changed; the coil was probably changed unnecessarily, but I didn't spend a lot to do it so it's fine.

The only other spark-related idea I have is replacing one of the wires. The one that was mis-seated got pinched between two parts when I was installing, and the insulation was slightly cut. I wrapped it with electrical tape -- but maybe that's not enough and something around it is interfering. (It's not still pinched, I moved it.) Also the metal on the end got a little bent, but I got it basically back to its normal shape. It's a pain to pull off the intake to get to it again, but cheap.

Beyond that, I'm really at a loss. I don't think there is an air issue. I guess it could be a fuel issue -- injectors? -- but not very sure what I'm doing there. I'm mechanically competent and can follow instructions and howto videos well, but am not the most well versed in all things car. Willing to do a little digging.

Again, the issue is completely random and doesn't seem to have a pattern -- but it does seem to be getting more frequent.

The only consistent thing is that it's cylinders 3 and 6. And because they're on the same coil "pack," I guess this is my reasoning for thinking it's a spark issue. An issue on one would cause an issue on both?

Going back to the very first instances, I think that was the same codes, but I honestly can't remember. Right before I changed the plugs I know I was getting codes for other cylinders as well, but since changing the plugs these are the only ones I've seen.

Helllllpppp.

I might go ahead and change that one plug wire tomorrow, but I don't really know where to go beyond that. If that doesn't do it I'm about ready to bring it to a shop and throw some money at it, but not having a good shop/mechanic that I trust right now, I'm just afraid they'll either tell me they couldn't find an issue, or jiggle some wires and say "we fixed it," and then a week and a few hundred dollars later the issue will simply reappear.
 

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2006 Kia Sportage V6 4WD
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Discussion Starter #3
Both. When they happen they'll start randomly and go away randomly. I think on the two worse occasions it included a few stop lights and a few miles of driving. After that it was fine.

When it happens, more throttle does seem to make a little bit of a difference. Or at least it will become less noticeable.
 

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2006 Kia Sportage V6 4WD
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10 Posts
Discussion Starter #5
Like swap cylinders, or put in new ones?

I've never done it and don't know where I'd start, but it looks like it could be done. But replacing all of them looks like it could be pretty expensive.

Because of how random it is, I guess my initial thought is that if it was a fuel delivery issue it'd be more regular. But maybe they're getting clogged randomly?
 

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2006 Kia Sportage EX 2.7L
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39 Posts
Yeah, that true. Sounds like it's going to be tough to figure out. It might be worth it to try some fuel addatives and a seafoam treatment. - where you suck it into the intake and smoke the neighborhood up. That's always fun at the least.
 

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2006 Hyundai Santa Fe Limited 3.5, 2008 Kia Sportage 2.0, 2005 Kia Sportage 2.7
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217 Posts
Same here. 05 2.7 with misfires on cylinder 3. Changed all the plugs as they had about 80k on them. Checked coils with a light and even swapped two coils. No visible misses on the light. Out scanner on it and only misses registering are on #3. Dwell is good and all injectors are firing evenly.
 

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2006 Hyundai Santa Fe Limited 3.5, 2008 Kia Sportage 2.0, 2005 Kia Sportage 2.7
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217 Posts
Same here. 05 2.7 with misfires on cylinder 3. Changed all the plugs as they had about 80k on them. Checked coils with a light and even swapped two coils. No visible misses on the light. Put scanner on it and only misses registering are on #3. Dwell is good and all injectors are firing evenly.
However, when checking the timing, it is jumping from 2 to 23 degrees at idle instead of starting around 10-12 degrees. I am sure this is my issue and was thinking the crank sensor but was wondering why the other cylinders aren't also missing. Thanks for any input.

Chris
 

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99 Kia Elan 1.8L, 17 Ford Edge Sport 2.7L V6, 15 Mustang 3.7L V6, 08 Harley Nightrain
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However, when checking the timing, it is jumping from 2 to 23 degrees at idle instead of starting around 10-12 degrees. I am sure this is my issue and was thinking the crank sensor but was wondering why the other cylinders aren't also missing. Thanks for any input.

Chris
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2006 Kia Sportage V6 4WD
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Discussion Starter #10
So I did go ahead and change the plug wire that got pinched during installation. I really had my hopes up that it would clear up the issue, but it didn't. Two days later the codes re-appeared (although the misfires weren't noticeable to me), and then Saturday night on two occasions it did the thing where it ran rough for a few minutes, and then went back to normal.

I also figured that if I had to resort to bringing it to a shop, it would eliminate one thing they could see as a potential fault. I would have felt really stupid bringing it somewhere, having them charge me $200 to change a wire, and it not fixing a thing.

I think I'm likely beyond my depth here, but still open to ideas.

My gut is that it's still spark/electrical, because if it was air, compression, or fuel, it seems like the issue would be more persistent and not totally random, like it is.

Not having a trusted mechanic at the moment, I'm just biting my nails. With the completely unknown nature of the problem it could get expensive. And I feel like I'm running the risk of them "fixing" something only for the problem to recur a week or two later, as it's done with every "fix" I've tried until now. Until this weekend I hadn't had the noticeable, rough-running misfires in several weeks.

I guess I could bring it in and tell them to start with diagnostics, and then depending on what they find decide what to do?
 

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2006 Kia Sportage V6 4WD
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10 Posts
Discussion Starter #11
Since timing was brought up, it also has me thinking, could the timing belt have something to do with this?

The belt(s) are due to be replaced soon, and I might be pushing my luck with regards to that since I don't truly know when it was replaced last.

That job will need to be done too, but I'm just curious if these are separate, or if they could be related.
 
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