High Idle problem - JeepForum.com
Search  
Sign Up   Today's Posts
User: Pass: Remember?
Advertise Here
Jeep Home Jeep Forum Jeep Classifieds Jeep Registry JeepSpace Jeep Reviews Jeep Gallery Jeep Clubs Jeep Groups Jeep Videos Jeep Events Jeep Articles
Go Back JeepForum.com > Models > Jeep Grand Cherokee & Commander Forums > ZJ Grand Cherokee Forum > High Idle problem

JK Front Lower Adjustable Control Arms!QTP Low Profile Cutouts Now @ MarylandSpeed- Free ShippingOPTIC ARMOR WINDOWS all sale now !!!!!!!!

Reply
Unread 02-19-2013, 11:57 AM   #1
ToothAke
Registered User
1995 ZJ 
 
Join Date: Feb 2013
Posts: 12
High Idle problem

summary:
I recently bought my first ZJ. Got a great deal and spent a whole weekend fixing it. runs great now except for a high idle in neutral or park. It drops down to normal in drive. But in neutral it is like a 1.2k RPMs.

Already checked:
Idle control valve. Clean as a whistle. looks new. cleaned it anyway.

Throttle control valve. was clean already also. no change.

I have been looking for a vacuum leak but cannot find one. All the hoses look great and plugged into the right spots.

Main question:
I noticed that the engine runs a little cold. But not too much. Gage goes half way to middle. whatever temp that is. I figured a lower thermostat was put in. But if this is the case. could the engine be choking and trying to warm the engine up but cant because of a lower thermostat?

any help would be great!!

ToothAke is offline   Reply With Quote
Unread 02-19-2013, 12:52 PM   #2
McCloudsZJ
Because RaceJeep
 
McCloudsZJ's Avatar
1998 ZJ 
 
Join Date: Sep 2011
Location: Roanoke, VA
Posts: 2,140
If you still suspect a vacuum leak, take some carb cleaner and spray it around the lines. If the engine stalls, or drops in RPM, you've found the leak. Silly question, but is the IAC plugged in all the way? I neglected to push the connector on all the way (I was in a hurry) after I cleaned my IAC and it idled high in neutral and park, but drove normally.
__________________
March 2014 GCOTM. 1998 Deep Slate 5.9
A few mods.
McCloudsZJ is offline   Reply With Quote
Unread 02-19-2013, 01:56 PM   #3
ToothAke
Registered User
1995 ZJ 
 
Join Date: Feb 2013
Posts: 12
OK I will check for vacuum leaks again in the morning. Could the IAC just not work even though it looks great? Is there a way to test it without getting a new one?
ToothAke is offline   Reply With Quote
Unread 03-04-2013, 11:46 PM   #4
ToothAke
Registered User
1995 ZJ 
 
Join Date: Feb 2013
Posts: 12
Checked all lines for vacuum leak and found nothing. Looked more into the idle control and saw PO had soldered one wire on it. So I went to the junk yard and cut off a plug. Stripped my wires and soldered new plug on and heat shrinked them nicely. Unfortunately it changed nothing. Idle is still the same. Next thing I can think of is to replace idle control and throttle positioner to see if that makes a difference
ToothAke is offline   Reply With Quote
Unread 03-05-2013, 01:07 AM   #5
AVR2
Registered User
1993 ZJ 
 
Join Date: Apr 2007
Location: UK
Posts: 1,936
Try tightening all the intake manifold bolts. It's not impossible that you have a leak around the gasket. That's what caused my high idle.
AVR2 is offline   Reply With Quote
Unread 03-05-2013, 10:45 AM   #6
ToothAke
Registered User
1995 ZJ 
 
Join Date: Feb 2013
Posts: 12
Alright I'll give the manifold a try. Shouldn't the gasket be changed if there is a manifold leak. Just wondering if tightening would help if they are not loose
ToothAke is offline   Reply With Quote
Unread 08-03-2013, 12:57 PM   #7
ToothAke
Registered User
1995 ZJ 
 
Join Date: Feb 2013
Posts: 12
I sprayed all the sensor connection on the TB with electrical cleaner and tightened the manifold. There was definitely lose bolts. I checked the valve covers too and they were all lose as well. Idles like a dream now. Thanks! Late post as well
ToothAke is offline   Reply With Quote




Jeep, Wrangler, Cherokee, Grand Cherokee, and other models are copyrighted and trademarked to Jeep/Chrysler Corporation. JeepForum.com is not in any way associated with Jeep or the Chrysler Corp.