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Unread 11-09-2009, 08:17 AM   #1
98xjnick
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1998 XJ Cherokee 
 
Join Date: Nov 2009
Location: Buffalo
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Rough idle, stumble at idle.

I have a '98 Cherokee with the 4.0, 136,000 miles. I purchased it about 18 months ago and it always had a little vibration/roughness at idle but very minor. Lately it'll stumble in stop and go traffic, usually after stopping for a short time like fueling up. It runs fine at higher rpm and power seems good. I did a tune up about a year ago, and have since checked that stuff over due tracking down another issue that turned out to be a faulty crankshaft position sensor. I also recently cleaned out my throttle body and IAC valve.

I have a scan tool that monitors the computer and my throttle position sensor reads 14.9% angle at idle. Does anyone know if this is normal for our Jeeps? Logically that seems like it might be the issue, but before I shell out for a new TPS, does anyone know any other issues that might be causing this reading, or my problem?

Thanks for the help.

-Nick

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Unread 11-09-2009, 08:24 AM   #2
tjwalker
It's the crank sensor!
 
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1999 XJ Cherokee 
 
Join Date: Nov 2007
Location: Central Minnesota, MN
Posts: 8,417
I don't know what the TPS reading should be at idle, but I would get a meter and a manual and perform the recommended testing on that hardware before replacing it. TPS can be tested.

Did your tuneup include plugs, plug wires, cap, rotor?

A bottle of high quality fuel injector cleaner (I like Chevron/Techron) in about 3/4 of a tank of gas is never a bad idea.
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Unread 03-23-2010, 03:18 PM   #3
vabeachtennis
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1996 XJ Cherokee 
 
Join Date: Jan 2010
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Quote:
Originally Posted by 98xjnick View Post
I have a '98 Cherokee with the 4.0, 136,000 miles. I purchased it about 18 months ago and it always had a little vibration/roughness at idle but very minor. Lately it'll stumble in stop and go traffic, usually after stopping for a short time like fueling up. It runs fine at higher rpm and power seems good. I did a tune up about a year ago, and have since checked that stuff over due tracking down another issue that turned out to be a faulty crankshaft position sensor. I also recently cleaned out my throttle body and IAC valve.

I have a scan tool that monitors the computer and my throttle position sensor reads 14.9% angle at idle. Does anyone know if this is normal for our Jeeps? Logically that seems like it might be the issue, but before I shell out for a new TPS, does anyone know any other issues that might be causing this reading, or my problem?

Thanks for the help.

-Nick
Did you ever find out what the problem was. I seem to have similar symptoms.
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