XJChang

I left my 2000 4.0 Cherokee sit for about 2.5 months because I left for college. My dad started it about 2 times in those months.
Today I went to drive it and it starts a little slow, a couple extra cranks than usual, and idles very low for a second then idles normal. After giving it gas of any sort it idles very low, 300 or less, sometimes dies. I drove it and it accelerates good enough but won't idle

XJChang

162,xxx miles

awg

I would consider a new fuel filter and some fresh gasoline if you have not tried these things,

check air filter and ducts for obstruction, could have a rats nest in there

tjwalker

Low battery charge can cause those exact symptoms. And if your vehicle sat for 2.5 months, even with dad starting it twice, low battery is high on the suspect list.

Job #1 is to fully charge the battery, then see where you are at. If still problematic, have the battery "load tested". Simple stuff first, always.

Good luck and keep us updated!

Jeepwalker

In addition too what's been suggested:

Look in the throttle bore and check for fuel build-up deposits. Clean with a solvent-safe plastic brush (not brass or steel!) and some throttle body cleaner ..if it's dirty. Don't forget to look behind or below the throttle blade. It only takes a little build-up, believe it or not, to screw up the idle air when the blade is almost all the way closed during idle. Check PCV valve and vacuum hoses, etc. Make sure the front and rear bolts on your rig's intake manifold aren't loose (they seem to loosen up after a while), which can 'suck air' and cause idle issues. Make sure your temp sensor is reading properly (use a scanner or ohm it out cold/warm & compare to an ohm/temp chart). Sensors can 'drift' in accuracy. The computer might 'think' it's a different temp than it really is thereby giving the incorrect air/fuel. Pull the air filter and make sure there aren't any rodent nests below (restricting airflow). Don't underestimate those pesky rodents!! he he.

Put some Heet, alcohol water-remover (in the tank) ...in case somehow the fuel you had in there has attracted moisture while you were gone. Condensation cycles can do that. And some Premium fuel might not hurt too in case your fuel has gone 'flat'. But mostly water could be an issue. Be nice if you could scan for any codes.

Best of luck!!

dzywicki

I concur with tjwalker. The XJs really don't like marginal batteries. I have had a wide variety of vehicles that I have been able to jump start/recharge a battery and all is good. I have a 98 and a 99 XJ and both have exhibited the same behavior with marginal batteries. Jumping/charging doesn't seem to do it with XJs. On my 99, I accidentally left the dome light on and it drained the battery. I put it on a battery tender and left it until it was solid green (fully charged and healthy). Still wouldn't idle so I hit it with the parts cannon and did troubleshooting on everything int he ignition system. Finally ran out of ideas, got a new battery and it went right back to normal. There are a ton of threads about XJs not liking marginal batteries. Good luck.

XJChang

Thanks for everyone's help. I cleaned the throttle body and IAC, got all carbon junk off. I dont have any problems with low idle anymore. However, it highlighted another problem. The RPM returns to idle very slowly. I put 5 gallons of 91 in, it was pretty much empty. I think my battery is toast, ive had problems with it in the past. Leaving the dome light on kills it very quickly and Ive been stranded waiting for a jump a couple times from leaving the hazards on for a few minutes

tjwalker

1. New battery as all engine life starts here. Be sure battery is fully charged upon installation.
2. Get a multi-meter and with one lead on each battery post and on DC Volts scale, you should see approximately 14.4 volts give or take a bit at a high idle. This is a fast and dirty test of your charging system.
3. Drive it for a while, your idle will probably reestablish itself at the proper RPM.