OK, I had that missing problem.
I finally found time to tear it apart and change those plugs.
Much needed... problem went totally instantly away.
Been gone now for weeks.

Now all the sudden it's starting back again with the new plugs.

It first missed a single time when I shifted into reverse. Now it's slowly getting worse. It misses really bad it seems any time that it is at idle and you have the brakes applied, and initially when taking off.

I know it could be something in the tank, or the fuel filter, or a fuel injector, or a plug wire, or a coil... or maybe the air filter (doubtful)... or maybe one of my new plugs is not so good (doubtful).

I'm trying to decide where to start here now?

Is there anything I have said that makes you lean to a certain direction for any reason?


I tend to lean away from the coils and wires, because it will do it when cold and gets no worse when hot. It's a shame you can't see in there to troubleshoot the old fashioned way (look for arcing in the dark).

What do you all think?

How many miles on your Sportage? If over 90K miles and the plug wires/coils are originals I would change them.

When you did the plugs did you notice oil on them? If yes then the valve cover gasket is leaking and could cause the misfire.

Is your CEL on? Mine just started running like crap the other day. Rough idle and backfiring. Took it in and they said the catalytic converter is plugged up. I've got a new one ordered so hopefully that cures it.

No oil on the plugs... the valve cover gasket is fine.
I was expecting to have to replace it before.
But I lucked out on that.

CEL... yes that came on today... twice (more later)
Rough idle... yes... real rough now.
Backfiring... no.

I had not thought of the converter, could be possible. I have been getting a vibratory noise from the exhaust during cold morning startups... just figured it was age and cold though.

I'll add the converter to the list of possibilities and have a look at it in the dark while hot.

OK, NOW... TODAY'S EVENTS...


I'll throw you guys another bone for food for thought on this one.

When I very first started having problems, once the CEL came on, I had it checked. Cylinder #4 misfire.

Then it seemed fixed for weeks after the plug change.

Well, today the CEL came back on. So I had it checked again. Cylinder #4 misfire again.



Now I'll take you on the trip that has been my thought process.

Please correct me if I am wrong here. I'm thinking the back cylinder should be #4... and if I am thinking correctly, the coil is on top of #4.

This makes me doubt it's the wires a little... more likey a long wire than a short boot.

This also makes be doubt it's the coils... unless these can possibly go bad on one side... else, shouldn't it effect the other cylinder also?

I'm suspecting a loose connection or ground...
Or the #4 injector at this point.


Oh, and I think the mileage is around 108,000.

When you put the new plugs in did you re-gap them first?

If you want to rule out the coil then swap the one over cylinder 2 with the one over 4. The plug wires will swap over between the coils. If the misfire moves to cylinder 2 you have found the problem.

And yes, the coil assembly to plug top CAN go bad yet still work properly for the plug attached via the external plug wire.

Yes... to spec...

That's what I had in mind to try.
I just wish I had something to check the codes myself.
Hate having to drive it out to check that.


Boy... I'm reeeealy hatin' the under-hood layout on these things right about now.... <img src="/forums/images/graemlins/baby.gif" alt="" />

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I just wish I had something to check the codes myself.
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Harbor Freight has an ODB II code reader for $39.99

Harbor Freight ODB II

JEGS also has one that looks pretty decent for $83.00

JEGS ODB II READER