Flat battery, CEL/Misfire?? - Jeep Wrangler Forum

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Old 05-02-2013, 07:45 AM   #1
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Flat battery, CEL/Misfire??

So Tuesday night I came home and reversed into my spot, only I forgot to stick it in 1st like I usually do. Half eleven that night I see the reverse light illuminating the yard, went out stuck it in 1st and thought nothing of it....

Big mistake.

Yesterday morning tried starting and got half a wet fart and sputter and nothing, dead battery (dick)!!
So I hooked up to the Mrs' pontiac and stole some power to get her going.
When I started up she idled real high, 2500 and showed no signs of letting up. So I shut her off and tried again, same. After about an hour of doing this the idle finally settled to about normal. Then the CEL started flashing, my diags read out p0300/01/02/03/04 Misfire on every cylinder.....
cleared it, pulled the plugs, clean the dizzy cap, rotor and points and still doing it....
The engine seemed to be running fine, fumes stunk to high heavens though, rich unburnt fuel.... fuel flow analysis had tripled at idle.
So I got fresh plugs to put in - Bosch Iridium platinum whatsits (Napa price $16 each, walmart price $10 a pair....) and whadya know..... no more codes!!
Fuel flow back to normal, exhaust doesn't stink like it did...... My question....

WHAT THE FRIG?????? Could this be caused by the dead battery screwing something up?

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Old 05-02-2013, 09:06 AM   #2
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Possibly, today's electronics like full voltage, dropping low can cause some screwy things.

You have other issues, reverse lights should not be on when the key is out.

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Old 05-02-2013, 09:54 AM   #3
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A Jeep with a dead or nearly dead battery won't run properly after the jump start battery is disconnected. The reason is its alterator is not self-exciting, it absolutely requires +12v from the battery before it can generate power. Yes I know that older vehicles & SOME modern vehicles can run fine without a battery once started but most (including Jeeps) will not.

For example, you can't even push start a TJ/modern Jeep if the battery is completely dead. Put your battery on a charger overnight & if the battery is still good, it'll be fine again in the morning.
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Old 05-02-2013, 11:33 AM   #4
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Quote:
Originally Posted by sparky View Post
Possibly, today's electronics like full voltage, dropping low can cause some screwy things.

You have other issues, reverse lights should not be on when the key is out.
Well, it wouldn't surprise me... PO really didn't take care of it....
Quote:
Originally Posted by Jerry Bransford View Post
A Jeep with a dead or nearly dead battery won't run properly after the jump start battery is disconnected. The reason is its alterator is not self-exciting, it absolutely requires +12v from the battery before it can generate power. Yes I know that older vehicles & SOME modern vehicles can run fine without a battery once started but most (including Jeeps) will not.

For example, you can't even push start a TJ/modern Jeep if the battery is completely dead. Put your battery on a charger overnight & if the battery is still good, it'll be fine again in the morning.

We're all good this morning, just a p1398 for a loose ground which I've since rectified.
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