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Unread 11-05-2009, 08:31 AM   #1
Titleistprov21
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1999 TJ Wrangler 
 
Join Date: Nov 2009
Location: Mass
Posts: 1
Rough Idle when Cold

Hi all,

I'm new the the Jeep community. Just bought a '99 Sahara with 127k miles. Absolutely love it!

I would appreciate any insight into my problem: When it is cold in the morning and I start er up, it has a very rough idle. Jumps from 500rpms to 1500 rpms very quickly and goes up and down like that until she warms up. and after the engine warmed up, my Check Engine light came on. I am going to run the codes today.

Even after the engine warms up, regardless of air temperature, sometimes it will idle at 600rpm, and other times it will idle around 1400rpms, but it doesn't fluctuate like it does when it is cold.

Any thoughts?

Thanks in advance for your help,

-Patrick

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Unread 11-05-2009, 09:10 AM   #2
OutermostJeep
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2009 JK Wrangler 
 
Join Date: Aug 2009
Location: Brewster, MA
Posts: 149
Throttle Position Sensor (TPS) ? Do a search for it and see if anyone's symptoms match.
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Unread 11-05-2009, 10:52 AM   #3
TheBoogieman
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1998 TJ Wrangler 
 
Join Date: Aug 2006
Location: Charlottesville, Va
Posts: 27,731
Welcome to Jeep forum.Clean the IAC with a good carb cleaner and you'll be fine.Post # 2 for details.Check the codes though and it will tell you exactly what's wrong.

http://www.jeepforum.com/forum/f9/iac-question-489089/
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When I had 3.07s I would draft behind birds as an attempt to do the speed limit.
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2000' WJ Limited 4.7L
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Unread 11-05-2009, 10:54 AM   #4
TheBoogieman
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1998 TJ Wrangler 
 
Join Date: Aug 2006
Location: Charlottesville, Va
Posts: 27,731
Quote:
Originally Posted by OutermostJeep View Post
Throttle Position Sensor (TPS) ? Do a search for it and see if anyone's symptoms match.
TPS would be the problem if it did it while driving and not just at idle.
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Quote:
When I had 3.07s I would draft behind birds as an attempt to do the speed limit.
---------------------------------
2000' WJ Limited 4.7L
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