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IndyJeepMan 11-06-2010 06:21 PM

Rough start after Jumping..
Jumping as in bridging a battery to start my Jeep :rofl:

First off, my Jeep is a 2000 4 cylinder with the Ax-5 and has about 70k on the engine.

So, I get off work today and I left my 5" fog lights on.. It used up all the juice in my battery. Anywho, It wouldnt even crank so I had a co-worker give me a jump. I work at Kenworth so they are all truck techs lol. So We get the connection going and I try and start the Jeep and it cranks and turns but no start.

I do this a few more times and still no start which usually the little 4 cylinder fires right up after a quick turn of the key. So I turn the key and give it some gas and she fires up. A little fuel smell came out and then she was running. I let of the gas and it dies. RPM's just drop so start it again and hold it at 2k rpm and then let it down slowly to the average idle of about 800-900 rpm.

Idles fine, revved it a few times and let it off and still went back to idle. Well I put it in gear and leave the parking lot. All the guages are fine and no CEL and everytime I let of the gas the RPM's dropped. Almost to the point where it dies, one time it did. So I got her home and when driving ran great, and at normal idle seemed fine. Then it went away and didnt have any more problems with going from driving to idle. But now when I start it pauses at like 400 rpm and idles rough for a half a second then goes back to fine idle and runs great,

Ideas on what it could be?

Bruck 11-06-2010 06:24 PM

Might be time for an I6 dude...... Sorry. I'm bored and totally unhelpful. Don't mind me.:blunt:

Jerry Bransford 11-06-2010 06:28 PM

It is absolutely 100% perfectly normal for the engine to barely run after jump starting your nearly dead battery. Your battery is still mostly dead and the alternator will not put out enough power with a nearly dead battery to properly power the ignition system.

Unlike older generators and some other model alternators, the TJ's alternator REQUIRES 12v from the battery to work. If the battery is dead, the alternator won't work at all and the engine will not run at all, at least not for long after the jump battery is disconnected. The engine will barely run if the battery is mostly dead.

The cure is to use a bench charger to charge your battery overnight. No, you should not expect it to charge well by just driving it as the alternator was never designed to recharge a completely or mostly dead battery. Once you have a fully charged battery, your engine will run normally again.

IndyJeepMan 11-06-2010 06:36 PM

Mr. Jerry Bransford..

Thank you! Will hook the charger up tonight. Didnt want to have to drop money on the 4, I'm trying to save for mods dangit! :cool:

That is a relief, and brucker. I do want an I6 lol. College is a money hungry place.

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