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Unread 12-26-2011, 01:53 PM   #1
dream
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1995 YJ Wrangler 
 
Join Date: Dec 2011
Location: elberton, GA
Posts: 11
95 YJ wont idle down

I have had Jeeps for years, mostly the older CJ series, so the newer(to me) stuff with fuel injection gives me trouble sometimes.
We have a 1995 YJ with 2.5 4 cylinder. We got it about a year and a half ago, and it has always idled higher than I think it should. Recently, it has gotten even higher. When cold, it idles up close to 1,500 RPM, then comes down after 10-15 seconds to idle at around 1,200 RPM. When pulling up to a stop sign, it will idle up around 1,500 for a few seconds, then go to 1,200. Has a 5 speed trans if that helps.
I have checked for vacuum leaks by pulling each hose off at the manifold one at a time and plugging the hole in the intake with my finger. Hasn't made any difference. Also tried adjusting the throttle stop screw(which is a PITA to get to). I have it back off completely. The throttle lever assembly isn't touching, and it has made no difference in the idle speed. Any ideas?

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Unread 12-26-2011, 02:17 PM   #2
jsawduste
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2006 YJ Wrangler 
 
Join Date: Jul 2006
Posts: 3,035
IAC Idle Air Control

Google it and your will understand what function is has on idle speed.
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Unread 12-26-2011, 03:17 PM   #3
oldtime_ironman
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1991 YJ Wrangler 
 
Join Date: Dec 2010
Location: 14304 Niagara Falls, NY
Posts: 2,540
Hi, Welcome to the YJ club! You've just found one of the best jeep sites anywhere!

The YJ's are pretty easy to work on once you get to know your way around the system - its one of the simplest out there. Jsawduste gives a good hint about the IAC. You can take it out and clean the IAC and throttle body very thoroughly - it gets gummed up around there. One thing too, which I *always* check, is the diagnostic codes from the computer. Its easy, all you need is the ignition key. Here's a video that shows how:
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Unread 01-02-2012, 11:57 AM   #4
dream
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1995 YJ Wrangler 
 
Join Date: Dec 2011
Location: elberton, GA
Posts: 11
OK, finally got around to looking this thing over. I pulled the IAC valve out and cleaned everything up. Lots of crud on/in the whole throttle body assembly.
Pulled the IAC out of the TB to clean it.
It doesn't seem to be seating in the valve body, and the plunger really doesn't move. I'm thinking the solenoid coil may be burned out, and the plunger is melted into the open position. Any advice on this? I'm currently trying to locate a new valve.
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Unread 01-02-2012, 12:00 PM   #5
jsawduste
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2006 YJ Wrangler 
 
Join Date: Jul 2006
Posts: 3,035
Time for a new IAC. Best is from the dealer. A few more $$ but a better quality parts.
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Unread 01-02-2012, 12:30 PM   #6
dream
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1995 YJ Wrangler 
 
Join Date: Dec 2011
Location: elberton, GA
Posts: 11
That's what I was afraid of. Found an OEM one online. It's on the way.
Thanks a lot for the help. I'll be back with more issues soon.
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Unread 01-02-2012, 07:06 PM   #7
YJs4Life
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1990 YJ Wrangler 
 
Join Date: Oct 2011
Location: ,, ,
Posts: 75
I'm not 100%, but I believe my '90 YJ idles around 1000. Maybe slightly higher like 1050 or 1100.
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Unread 01-02-2012, 07:20 PM   #8
YJames90
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1990 YJ Wrangler 
 
Join Date: Jul 2007
Location: Dutchess County, NY
Posts: 6,928
Quote:
Originally Posted by dream View Post
I have had Jeeps for years, mostly the older CJ series, so the newer(to me) stuff with fuel injection gives me trouble sometimes.
We have a 1995 YJ with 2.5 4 cylinder. We got it about a year and a half ago, and it has always idled higher than I think it should. Recently, it has gotten even higher. When cold, it idles up close to 1,500 RPM, then comes down after 10-15 seconds to idle at around 1,200 RPM. When pulling up to a stop sign, it will idle up around 1,500 for a few seconds, then go to 1,200. Has a 5 speed trans if that helps.
I have checked for vacuum leaks by pulling each hose off at the manifold one at a time and plugging the hole in the intake with my finger. Hasn't made any difference. Also tried adjusting the throttle stop screw(which is a PITA to get to). I have it back off completely. The throttle lever assembly isn't touching, and it has made no difference in the idle speed. Any ideas?
Same here but on the 4.3
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Quote:
Originally Posted by Poke View Post
Spring Over is not for you.... yet





My 2.5 to 4.3 swap thread
http://www.jeepforum.com/forum/f12/4...begun-1237704/
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Unread 01-17-2012, 12:02 PM   #9
Schaef81
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1990 YJ Wrangler 
 
Join Date: Mar 2010
Location: Lititz, Pennsylvania
Posts: 322
Did the IAC fix the problem. I have the exact same issue. At first I thought my TPS Sensor was not calibrated correctly and in fact it wasn't. The ratio between output/input was way off so I got it within spec and still have the same issue (high idle at stop till warmed up).
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Unread 01-17-2012, 12:08 PM   #10
SnowYJ
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1988 MJ Comanche 
 
Join Date: Jun 2009
Location: OR
Posts: 1,058
let us know if that was the cure!
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I go to college and I drive a Jeep.
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Unread 01-24-2012, 05:50 PM   #11
dream
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1995 YJ Wrangler 
 
Join Date: Dec 2011
Location: elberton, GA
Posts: 11
Sorry to take so long to get back. I put on the new IAC valve and it made no difference. Then I started looking around under there. I saw another post on this, and it was a leaking intake manifold. I checked the bolts, and two of them had actually fallen completely out. The others were loose. I put new bolts in and tightenned everything up, and it now idles at a sedate 800 RPM. DUH!!! It was right there looking at me, and I didn't see it. Story of my life. Overlook the obvious until it slaps me in the face. LOL!
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