My car wont stay started after i had unplugged and re plugged battery..

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Asked by WhisperMe Oct 08, 2015 at 02:17 AM about the 2006 Hyundai Sonata

Question type: Maintenance & Repair

well my oldest unplugged the battery to change a head lite bulb . yes i know ..anyways now after reconnecting. car wont stay started.. dies .

8 Answers

1,925

Don't understand "Unplugged the battery", do you mean "disconnected"? The battery only starts the car, once started the spark plugs derive spark from the alternator. If the car starts, its a good chance the batter is good and hooked up correctly. However, she may have disconnect another wire that leads from the alternator to the coil pack (which sparks your spark plugs). Look for any more disconnected wires from the alternator to the coil

2 people found this helpful.
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ok after she reconnected the battery, started the car, it ran for like 1min then died. and while its running.. it very loopy/runs ruff at times

3 people found this helpful.
40

so(1) disconnect battery .(2) turn ON head lights ..wait like what 30mins? then(3)turn OFF head lights (4) reconnect battery (5) restart car . and run 20mina or so..... i dont know if she touched the bulb but i think she did.. and if it doesnt bulb lite doesnt work but car DOES.. ill repeat this from steps after i replace headlamp bulb ..pray she didnt touch it ggrr . ill get back to u..thanks

1 people found this helpful.
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ok car still doing the same i guess next is map censer what i call it... off there air filter,, its a used part bout 4mths old.. acts same.. just funny it just did this at bulb changing time..

1,925

Your ECM might be completely bad. If all you did was disconnect the ground and replace a headlight. It should have booted right back up with this stock programming in tact. If it only stays on for a minute you might have a fuel pump relay issue. There could be a short and the fuel pump relay is overloaded and then turns off. If you are giving it gas, does it die?

2 people found this helpful.

I had this same problem. Engine runs rough below 1K rpm and then dies. Best thing to do ahead of switching out an old battery is to connect a device that keeps 12V power to the car and computer while the switch is made. Just be careful with the positive battery cable. It'll still be live after disconnecting it from the original battery. Wrap and tape it with something to insulate it. Now if you already disconnected the battery or it simply went dead... This is what I did. Be sure to do this when there is little or no traffic around, as it can be slightly hazardous. You'll have to drive with 2 feet. Right foot on the gas pedal and left foot on the brake. Start the car and keep the RPMs up high enough so it wont stall. 1K to 1.5K is what it took for me. If you can drive to a long section of road that doesn't require any stops, that's the best. You have to drive the car for at least a couple of miles with varied speed to get it to reset the computer. In my case, in a small town with stop signs everywhere, I ended up stalling the engine a few times. But after a couple of miles or so, the computer relearned what it must have forgotten when the battery was disconnected. The engine stopped stalling and the smooth idle returned to 700 RPM or so. One other thing. My 2008 Sonata also triggered an MIL code for the mass air flow sensor. An easy fix for me since a have an OBD2 scanner and code reader. Nothing wrong with the sensor, the computer must have thrown the code while it was still confused by the battery switch over. I simply erased the code and it never came back. Hope this info helps. Please be careful while driving 2 footed. It can be risky depending on traffic conditions.

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