01 Sportage intermittent power loss w/no pattern

[brettclancy]

The dealer can't even figure this one out so I thought I'd turn to the professionals here. 01 Sportage experiences intermittent power loss with no discernible pattern. Engine will remain running during these random events but the car will have to be shut off and allowed to rest anywhere from 1 minute to 15 minutes before resuming normal operation. This is extremely frustrating. I have done the following to attempt to rectify (some of these also needed done as part of regular maintenance): changed the oil (regularly of course), changed plugs and gapped @ .44, changed plug wires, changed plug wire harness, changed both coils, cleaned MAF sensor, changed air filter, changed canister, changed CCV, changed timing belt (entire kit w/ water pump), checked all hoses for leaks and wires for shorts, changed fuel filter, I even went so far to drill small holes in front of the 2nd converter just to bypass (no change so resealed the holes). I have done all I can think of. The dealer even checked all of my work when they did the worthless $100.00 diagnosis. They have had it twice and told me it was a loose plug wire connection the first time. Picked it back up and it did it again. They had it a second time and they told me it was a loose coil wire connection... it did it again. They currently have it for a third time and have spent the majority of the day on it with no answers. The car drives great and it should with all of the repairs I have done. It seems that after it gets hot it will do its power loss thing. Shut it off and wait, restart it and resume your driving with no issues. The check engine light will blink when it looses power and it used to stay on with a code (usually misfire, can't remember exact codes right now) but the last two times it has done this The CEL has blinked upon power loss but does not stay on with a readable code. No CEL, no codes. I read a later post about the baffle breaking loose in the gas tank but it doesn't necessarily happen when breaking or sloshing fuel around. It can happen on a flat straight road at the speed limit. Obviously I'm looking for any professional suggestions and also hopefully an opportunity to educate anybody else that might experience this problem. I have searched the threads and have not seen any with this unique problem. Any advice would certainly be appreciated. I am looking forward to your responses.

[brettclancy]

So I picked the car up from the dealer yesterday after they spent an entire day diagnosing it (at no charge). Their response was "you didn't use NKG plugs and you also used an aftermarket coil". Said that is the problem. They had it torn down twice and didn't see this but caught it the third time. I don't know if that is really the issue but will change them out just to make sure. Maybe this will be the fix. I haven't heard anything about using an original Kia coil. Does this sound right to anybody. I will change the coil and plugs and post the outcome.

[LMP]

Since you had a misfire code, a faulty coil, or any ignition component, can be involved; this engine is prone to ignition problems (hot environment and oil contamination) so it would not be a surprise. Oil contamination of rear plugs by leaking cover gasket is not rare. Ignition wires are also a common cause of problem but you took care of this issue. It is bizarre that NGK platinum plugs have been tagged as a problem by some....but I'm reluctant to put the blame on any plug that is compatible with that car.
Knock sensor failure default mode would retard engine timing in a noticable way but not to the point the car is unconfortable to drive.
Gapping the plugs closer lowers ignition voltage and this can avoid stray arcking if coil or wiring is at risk. So a test on this alone – closing to .025 – is a good test; of course it might lower top end performance but if power loss stops or occurs much later, it is a good indication of the nature of the problem.
Loss of fuel pressure - for heat dependant fuel pump problem of clogged fuel filter - is not to dismiss...but a fuel pressure test would be useful in that option. I would not change the fuel pump except if totally confirmed by tests.

Keep us informed of progress or other symptoms .

[brettclancy]

So, it has been a while since I posted but i wanted to update. I did put the "correct" plugs and Kia coils in. I would love to say that was the fix, unfortunately... I will say though it ran a little better but still power loss especially accelerating up hill. Oh Yah, I also gaped to the plugs to .035 instead of .044. Also having a problem with dropping into passing gear. I tried something. I separated the #1 converter from the exhaust manifold, took it out for a pretty loud test run and power has returned. Assuming a melted converter from the previous mis-fires. Why a Kia dealership couldn't figure this out, I'll never know. I'm a simple driveway mechanic trying to save a buck in a tight economy. I thought this power loss problem was over my head so I knew the "pros" had to look at it. I have spent a lot of money on this problem and the dealer was certainly no help. I'm curious how they spot a failed converter. Now here's another question, can I avoid the expense of a new converter by hollowing out the failed one or will it damage the the computer and o2 sensors? I'm probably gonna just change it but I am still curious.

[brettclancy]

Yet another update... I removed the #1 converter only to find it mostly empty. Seems the guts of the cat have crumbled and collected int the exhaust pipe between the #1 and #2 cats. So I am going to empty out the crumbles and reinstall the old hollow cat. Found that a new one takes close to $400.00 from your wallet, ouch! gonna have to wait till I have the funds to swap 'em out. So far CEL hasn't come on even with the clogged exhaust. Don't really understand that one. I'll post the outcome of running with a hollow cat. This whole ordeal has been very frustrating. I wish the dealer would have thought to consider the possibility of a failed cat. I guess I'll have to trust my simple diagnosing skills more in the future.