Hey there new on the site don't know if this is where to ask questions but here it goes.
have a 98 Jeep Cherokee XJ and for the past month I have been having idle issues on start up it almost sounds like a dead battery but if you keep on it it will eventually turn over. But even when you do get it turned over, there's still a chance that it Will not idle high enough and just die out. Sometimes the gas gauge doesn't work properly when it does this, don't know if that's connected. This does not happen every time, it does not just happen in the morning it happens when ever there has been absolutely no pattern. Have a video of it doing This but can't seem to upload. This is my first jeep and love it and don't want to part with it! Please help!

 

First thing to do is clean and tighten all your grounds and battery cables.

If that doesn't fix it, next I would take a trip to your local Autozone or other parts retailer and have them do a battery load test and an alternator test just for giggles. It's free and you'll know for sure the parts are good.
Assuming your battery is ok (which can exhibit those symptoms when dying), the next thing would be to do a fuel pressure test. As you're already at the parts store, grab a fuel pressure tester (it's a loaner tool - leave a deposit and get it back upon return) and test the pressure.
Your pressure should be 49 +- 5 psi.

If everything tests good at that point, you can go from there.

 

Thank you so much for your reply! I will be spending Saturday checking and cleaning everything! Hopefully it's just a ground like you said. Thank you again!

 

You're quite welcome.

Welcome to the forum - you'll find a lot of great folks (most a lot smarter and more knowledgeable than myself) are regular posters. You definitely asked in the right place and the right way.

 

 

I'm with the others.

1. Load test battery (free at parts store) A marginal battery CAN be strong enough to start the vehicle but marginal enough to give the engine management system fits.

2. Either have your charging system checked as well or a quick and dirty test you can do is to put a meter on the battery. At a bit of a high idle, you should have about 14.4 volts, give or take a bit.

3. Freshen all engine grounds. See below.

4. Clean the idle air control and throttle body. Easy to do and can help. See below.

5. For any new-to-you vehicle, take stock of tuneup hardware. Fresh Champion plugs gapped to .035, quality plug wires, cap and rotor can really help unless you have BELIEVABLE evidence that this has been done recently.
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The Idle Air Control (IAC) is mounted on the back of the throttle body. (front for 87-90) The valve controls the idle speed of the engine by controlling the amount of air flowing through the air control passage. It consists of a stepper motor that moves a pintle shaped plunger in and out of the air control passage. When the valve plunger is moved in, the air control passage flows more air which raises the idle speed. When the valve plunger is moved out, the air control passage flows less air which lowers the idle speed. Over time and miles, the IAC can get carboned up which can have an adverse affect on idle quality. Cleaning the IAC may restore proper function and is an easy procedure to perform and good preventive maintenance so it is never a bad idea.

CLEANING THE JEEP 4.0 IDLE AIR CONTROL

Remove the air filter cover, associated hoses and the rubber boot that goes from the air filter cover to the throttle body. Remove the IAC with a torx driver (2 bolts; one can be kind of hard to get to)

“Gently” wiggle out the IAC from the throttle body. Gasket on the IAC can be re-used if it is not damaged

Clean the IAC with a spray can of throttle body cleaner; inexpensive and available at any place that sells auto parts. Throttle body cleaner is recommended rather than carburetor cleaner as it is less harsh, safe for throttle body coatings and is best for this task. Use cleaner, a rag and a toothbrush and or Q-Tips. Be gentle; don’t twist or pull on the pintle that protrudes from the IAC as it is fragile and you could damage it.

Thoroughly spray clean and flush where the IAC seats in the throttle body with the same spray cleaner

It is also a good idea to clean the entire throttle body itself, the butterfly valve inside of the throttle body and all associated linkage as long as you have things disassembled

Reinstall IAC and check idle quality
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Grounds can be the root cause of many electrical gremlins. Refreshing grounds is NEVER a bad idea, and the investment of your time in this procedure is always well worth it!

You can't tell much of anything by looking at ground connections!! You must remove, scrape, clean until shiny the cable/wire ends and whatever they bolt to. Be sure to remove all paint from any ground connections.

Start with the one on the back corner of the head, and where it attaches to the firewall, as it deteriorates over time and is an area that makes it susceptible to damage. Best to replace that woven cable with a #4 or #2 gauge cable. You can attach the one end to the intake manifold if you would like.

Next go over to the engine dipstick tube stud. Remove the nut and clean the wire ends and scrape the block until shiny at the stud. Reattach tightly.

If you are so inclined, add at least a #6 cable from the negative terminal of your battery to one of the bolts on your radiator support.

 

subscribed.. this is good stuff.. thank you

 

tjwalker - Great stuff - very thorough and well written!

Mel - Autozone will do that battery load test and alternator test right on your car (meaning you don't have to remove any parts or disconnect anything) and free of charge (assuming you're in the U.S...). Just take your Jeep there and ask. It is pretty quick and painless and will set you in the right direction for fixing the problem.

Also, please report back - especially when you resolve the problem so folks in the future can find the symptoms and actual solutions. Plus it's nice to know when you've successfully helped another Jeeper.