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fix it man
fix it man, Master Technician
Category: Kia
Satisfied Customers: 17406
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Last week I got a flashing check engine light on my 2006 Kia

Customer Question

Hello. Last week I got a flashing check engine light on my 2006 Kia Rio, 1.6L DOHC, manual 5 speed. 39K miles on the car; I purchased used a year ago with 34K miles from the original owner. The car has run fine for the last year. After the check engine flashing light, I drove it home (5 mi) and have parked it at the house. I have only run the engine while trouble shooting. It hesitates slightly at lower RPM; it becomes less noticeable at on-speed RPMs.
Diagnostic indicates P0302 (cylinder 2 misfire). I replaced all spark plugs and inspected all the spark plug wires and coils. The same code reappeared. After re-inspecting the #2 spark plug, I noticed a light coat of oil on it. Upon reinspecting the old #2 spark plug, it appeared to have some oil on it, too. Not dripping, but a mist-like coat. When looking onto the piston head through the spark plug tube with a flashlight, it also appears to also have some oil/grime on it and it smells like oil and gas compared to the other spark plug tubes.
I think I need a new #2 piston ring. However, this seems too early for a vehicle with only 39K miles. I have run it regularly for a total of 5K miles within the last 12 months. Any other ideas? I have not checked the compression since I don't own a compression gauge, but I think it's likely a mechanical, not electrical, one.
Submitted: 2 years ago.
Category: Kia
Expert:  fix it man replied 2 years ago.

Hello, my name is Bobby. Thank you for the question. Can you tell me if you can feel the misfire everytime you drive it?

Customer: replied 2 years ago.
Hello Bobby. I can hear a slight misfire at idle when observing the engine with the hood open. It sounds like a rough idle. However, the engine does not seem to shake/rock. It has never back-fired, either. Just before the check engine light illuminated, I felt the car studder a little bit while releasing the clutch pedal . I was in stop-go traffic so I was mostly using 1st gear. The light came on solid, then started blinking about 2 minutes later. When I got up to speed, the light went out, then came back on blinking whenever I slowed down. The low fuel light had illuminated about 3-4 miles prior, so I thought it may be a gas pressure problem. I put about 3 gal of 93 octane in the tank and wiped off the gas cap gasket with a gas station paper towel. The problem persisted (flashing check engine light), but then at all speeds.The bot***** *****ne is that I feel a slight misfire with some additional front-end car vibrations (mostly in the clutch pedal) at lower speeds -- primarily 1st gear. At higher speeds, the vibration is not perceptible and there does not appear to be a loss of power or speed capability. The car gets-off the line fine in first gear with the normal amount of throttle as the clutch is released.Every time I start the car, the check engine light will not be on. Then, it will illuminate flashing after the car idles for about 20-30 sec. This even occurred after I disconnected the battery cables to clear the P0302 code. I'm trying to identify a cause that may be easier to repair than a piston ring job. A piston ring shrinking or cracking after only 39K miles doesn't make sense to me. The car is not losing noticeable oil and I've never had to refill it between 5K mile oil changes (only one oil change since I've owned the car). The factory power train warranty is only 6 yrs/60K miles for second-hand owners. The 10 yr/100K warranty only applies to original owners, unfortunately. I have not checked to see if there may be a recall for this issue.The CARFAX on this vehicle is clean. It was registered to the original owner in Feb 2006 and he provided me full maintenance records. All routine service, no repair work.Thanks,
Expert:  fix it man replied 2 years ago.

Thanks Derrick. Before getting into replacing anything else you really should do a compression test. Though it has low miles this engine does have a history of valve seat issues. If the compression is fine then it may simply be a clogged fuel injector.

Customer: replied 2 years ago.
Thanks, Bobby. This makes sense regarding the rough idle, but the oil indication on the spark plug tip still confuses me. I dropped it at a local auto shop this afternoon and showed the mechanic the old spark plugs. He told me its very unlikely a piston ring problem. I'll let you know what he concludes; it'll be good to have a second opinion. Derrick
Expert:  fix it man replied 2 years ago.

Please do let me know. Most of the time the oil enters externally from a valve cover gasket issue. If it is from the inside then it may be a piston ring or more commonly on this engine a bad valve guide seal.

Customer: replied 2 years ago.
It turned out to be easier than I suspected -- it was a bad ignition coil. When I troubleshot last Saturday I had even purchased a new one from Autozone, but the oil on the spark plug tip threw me off. I chose to return the coil for a refund instead of installing it. I suspect that the plug may not have been firing hot enough to burn off all the carbon and/or oil that may have been getting sucked in from under the valve cover if the piston was not fully firing. I should have swapped coils and checked the ODB code to see if the problem migrated to another cylinder before assuming it was a mechanical problem. Then I could have replaced the faulty coil with the one from Autozone. In hindsight I also could have checked the coil's resistance. $102 for a new coil, $82 for troubleshooting, labor, and shop supplies. $200 with tax. It could have been a whole lot worse -- I'll check the ignition coil if this reoccurs on another cylinder. Questions: 1. Can you tell me what the proper ohm reading should be for a functional ignition coil? 2. What's the typical life of these coils? I didn't see any carbon witness marks on inside of the coil and maybe just a slight amount of rust on the exterior of the ignition coil tube. I live in New Orleans, so the high humidity may have caused some internal corrosion that contributed to a short? Thank You, Derrick
Expert:  fix it man replied 2 years ago.

I am glad it was that easy. As for the coils themselves they typically only last about 80,000-100,000 miles. Let me get you the resistance specs of them as it is not commonly used.

Customer: replied 2 years ago.
Bobby, last question. If the cylinder was misfiring, is there a chance that fuel has mixed with oil and I should do an oil change? When I looked at the spark plug tip last week it was not wet with fuel and the mechanic did not mention anything to me about an oil change. Thanks, Derrick
Expert:  fix it man replied 2 years ago.

It would take a really bad misfire to cause this for a long time. Doing an oil change though is cheap and easy to take care of just to be safe.