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2004 Kia Optima 2.4/Automatc
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Discussion Starter #1
Running at highway speeds the car will die for about a half second. The check engine will flash and all power to the air conditioner and radio goes away.

Comes back to life and runs with no check engine light. No codes are stored when checked with an OBDii reader.

This will occur about 15 times over a period of about a minute and then clear up. I have to stop and shut off the engine to get the air conditioner to work again. Did this today a couple times on a 150 mile trip.

Runs great and gets 31 mpg when not stalling/dying. Checked all battery connections, pressed on all fuses and relays, traced battery cables to alternator and starter and all are tight. Battery is at 12.70 volts when engine is off so I know it's charging good. Water levels are good on battery.

2004 Kia Optima SE 2.4 cylinder Automatic Transmission 116,000 miles
 

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1999 Kia Sephia, 2016 Kia Optima SXL, 2019 Kia Soul Plus
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Running at highway speeds the car will die for about a half second. The check engine will flash and all power to the air conditioner and radio goes away.

Comes back to life and runs with no check engine light. No codes are stored when checked with an OBDii reader.

This will occur about 15 times over a period of about a minute and then clear up. I have to stop and shut off the engine to get the air conditioner to work again. Did this today a couple times on a 150 mile trip.

Runs great and gets 31 mpg when not stalling/dying. Checked all battery connections, pressed on all fuses and relays, traced battery cables to alternator and starter and all are tight. Battery is at 12.70 volts when engine is off so I know it's charging good. Water levels are good on battery.

2004 Kia Optima SE 2.4 cylinder Automatic Transmission 116,000 miles
Hows the ground cable look, especially where it mounts to the body? I had a 07 Sorento come through are shop last week with a no start/no lights/nothing. The tech was chasing the power side and couldn't figure out why there was nothing. I figured out the battery ground cable where it bolts to the body looked okay, but was not making good contact and causing the problem. What you're experiencing reminds me of that. Its possible to have it look okay, but not make good contact. I would remove the bolt and scrape the paint away around the mounting hole and the cable end.
 

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2004 Kia Optima 2.4/Automatc
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Discussion Starter #3
@Pacos can't locate where the negative cable attachs to the frame. However I checked the engine at night and saw arcing from the spark plug wires. Pulled a plug and I believe these are the original plugs. NGK PGR5C-11 and well worn. Bought the car used last month so have no idea if they were ever replaced.
Ordered new plugs and 2 wire cable set at the KIA dealer. I'm not one for aftermarket electrical items as I learned my lesson on Toyota's with aftermarket ignition stuff.
Will install new air filter and clean the MAF sensor as well.
Will attach a UltraGauge OBDii reader and leave it installed for a while to see if any codes are being stored.
 

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2004 Kia Optima 2.4/Automatc
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Discussion Starter #4
UPDATE
I can now replicate the problem while the car is sitting in my garage with the ignition key on but the engine not running.
When I slam the hood closed the radio will come on. Taking a rubber mallet to all items in the engine compartment will not cause the problem. Only slamming the hood.

Looked for items sticking up that the hood might hit and I discovered an interlock switch that looks like your normal door open switch on a door only a rubber bumper on the hood activates it. The switch is directly behind the passenger headlight. Anybody know what that switch is for? Googling it didn't get me an answer.
 

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1999 Kia Sephia, 2016 Kia Optima SXL, 2019 Kia Soul Plus
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Thats just your hood switch for the ETACS system (burglar alarm). Still sounds like you have a poor ground causing the issue. I'll have to take a look at a fellow techs Optima to see where the ground cable mounts on the body. I would suggest tightening any ground cables you can see.
 

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2004 Kia Optima 2.4/Automatc
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Discussion Starter #6
UPDATE......The radio on and off can be caused by banging on the radio itself so I think that problem is somewhere in the connections to the radio itself. Will have to pull it out.

Meanwhile we have replaced the 2 spark plug wires and the plugs themselves and greatly reduced the sparking you could see at night but not completely. So I pulled the coil over plug assemblies today and cleaned them thoroughly and also installed wire conduit on the regular wires that are routed through the spark plug area. That cleared up all the hesitation on acceration issues and sparking by the plugs.
However...there is slight sparking from the air intake to the rear of the cylinder head....only when you first rev up the engine. There is a high voltage wire that goes into the air intake assembly that attaches to the intake manifold. HUH? Tomorrow I will pull the two nuts that cover up the assembly off and see what connects to the high voltage wire (looks like spark plug wire.).
Thanks for your support and I am looking forward to finding the battery cable ground just because I want to know where it is. I don't think it's a problem now but want to check it anyways as long as I'm goofing around with this thing.
 
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