99 Cherokee Idle wants to stall. - JeepForum.com
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Unread 04-22-2012, 01:49 PM   #1
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1999 XJ Cherokee 
Join Date: Apr 2012
Location: Dodge Center, MN
Posts: 2
99 Cherokee Idle wants to stall.

I am having a persistent issue with my 99 Cherokee (4.0L)

Regardless if the engine is warm or cold, rain or shine in gear or not the engine will start idling rough and want to kill for about a minute after 4 or so minutes of running. After that the idle will correct itself and be smooth.
It almost acts like it is not getting spark because if I try to give it a little gas I can hear what sounds like small back fire.

I had the engine checked for codes last October (none), since then I have run a couple of bottles of Lucas brand injector cleaner through it thinking dirty injectors. I have replaced the plugs, wires, cap and rotor and the problem still persists.
I was thinking a timing issue, but I would think that it would idle rough all the time if it was that.

I am no mechanic but if I take it apart, I can get it back together without extra pieces.

If anybody can point me in the right direction I would much appreciate the advice.

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Unread 04-22-2012, 01:58 PM   #2
It's the crank sensor!
tjwalker's Avatar
1999 XJ Cherokee 
Join Date: Nov 2007
Location: Central Minnesota, MN
Posts: 8,432
Welcome to the Jeep Forum......

I don't think this is a spark issue, and base timing is controlled by your computer; it is not adjustable.

First thing I would do if this were in my garage would be to hook up a fuel pressure gauge on the schrader valve on the fuel rail. Watch the fuel pressure and see if it remains consistent when the symptom occurs.

For a 99, you should see 49 psi, plus or minus 5 psi.

There certainly are other possibilities and this is a strange symptom, but consistent fuel delivery should be confirmed early in the troubleshooting process.
99 Cherokee, 4.0 AW4, NP242
Past Jeeps: 49 Willys, 81 Scrambler, 88 Comanche
Without "data", all you have is an opinion!
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Unread 07-09-2012, 07:34 AM   #3
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1999 XJ Cherokee 
Join Date: Apr 2012
Location: Dodge Center, MN
Posts: 2
Sorry for the very late reply but this problem is half fixed.

The dying on the side of the road issue is resolved (with a new fuel pump) but for some reason I still get the rough idle issue.

I need to replace the entire exaust (header back).
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