98 won't idle

Hey all,
Here's the deal. Every so often i'll hop in my 98 and start it. It will turn over and turn over but not fire. Then I give it some gas and it fires - until I take my foot off the gas. Then it stalls.
This is the big clue - I go under the hood and disconnect the battery for a couple seconds to allow everything to reset and clear, hook it up again and it starts and runs like normal. I'm thinking a relay, sensor or computer problem and just don't know where to start.
Thanks for any help.
joe

I had the exact same problem this past week. The Jeep would not idle after sitting overnight or when trying to go home after work.

Have you tried to start it and keep your foot on the gas to keep the idle up for a couple of minutes? When I did this, the idle would finally get set and it would run fine from then on.

How does the engine sound when you crank it over? Does it sound really weak until the engine starts? I did a load test on my yellow top and it would go down to 8 volts when cranking. Even though it showed 12.6 volts when standing and 13.8 volts when running.

Evidently, as it was explained to me, a cell (or something) can go bad and the ECU can "forget" the idle setting. I guess this happened because of extended winching and welding. And a good battery should only go down to like 11 volts when cranking.

Well, I just got back from 4WP with a new red top (20% off) and the Jeep now starts instantly. Hopefully, this will be the end of the problem.

If you have a voltmeter, do a load test.

Remove and clean throttle body and iac motor.

check your batteries, yellow tops are not intended for every day use.

jeepurnaz said:

check your batteries, yellow tops are not intended for every day use.

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Where did you hear that Yellows are not for everyday use? I checked the web site and couldn't see that anywhere? I've been using yellows in my vehicles (three vehicles, one boat, 5 total batteries) for a few years now and have only had one go bad on me. I'm not saying it's not possible, I just argue the statement that they're not for every day use.

i called optima cust serv at one time they told me tho yellow tops will work in a every day use application, they are better suited for deep discharge(ie winch) and then a recharg
in my 2x batt setup, i use a red for starting and normal power, all accesories and winch are connected to a yellow. if you look at specs, yellows have a lower cold cranking and cranking amps, but larger reserve capacity. have the batt your ign sys uses load tested, just checking batt voltage with a voltmeter wont tell if its got a bad cell. mopar products are very sensitiv to
amps and voltage when starting.

jeo said:

Where did you hear that Yellows are not for everyday use? I checked the web site and couldn't see that anywhere? I've been using yellows in my vehicles (three vehicles, one boat, 5 total batteries) for a few years now and have only had one go bad on me. I'm not saying it's not possible, I just argue the statement that they're not for every day use.

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Dumb question but why don't you pull the codes before you reset them?

jeepurnaz said:

i called optima cust serv at one time they told me tho yellow tops will work in a every day use application, they are better suited for deep discharge(ie winch) and then a recharg
in my 2x batt setup, i use a red for starting and normal power, all accesories and winch are connected to a yellow. if you look at specs, yellows have a lower cold cranking and cranking amps, but larger reserve capacity. have the batt your ign sys uses load tested, just checking batt voltage with a voltmeter wont tell if its got a bad cell. mopar products are very sensitiv to
amps and voltage when starting.

Click to expand...

Will do. As soon as I get home from work (Thursday). Thanks.
The only thing that doesn't make sense is that I have the batteries hooked up in parallel constantly (750ccax2=1500cca constant), they were bought at the same time to the internal resistance should be the same. I suppose they could both have bad cells, but I find that unlikely. I'll check it all out and get back to you. Thanks again.

langer1 said:

Dumb question but why don't you pull the codes before you reset them?

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Not a dumb question. I just don't know how and haven't bothered to learn.