High Idle on Grand Cherokee - JeepForum.com

 
LinkBack Thread Tools
post #1 of 11 Old 03-23-2012, 10:48 PM Thread Starter
IdahoVandal75
Registered User
1997 ZJ 
 
Join Date: Mar 2012
Location: Moscow
Posts: 1
High Idle on Grand Cherokee

So I have a 1997 Grand Cherokee with the 4.0 I6. Its my first jeep ever so i'm pretty excited about it. So I'm having issues with a very high idle when i put it in park. Driving is fine except when i put it in park its shoots up to around 2000 rpm and fluctuates around that range. So myself and a buddy of mine who is an ase master tech looked all over for a vacuum leak only not to find one. So then we checked the idle air motor and found it to be pretty stiff meaning it did not move back and forth easily. So we replaced that but its still having the same problem. Could it possibly be a bad tps sensor?

IdahoVandal75 is offline  
Sponsored Links
Advertisement
 
post #2 of 11 Old 03-23-2012, 11:31 PM
ratmonkey
R.I.P.
 
ratmonkey's Avatar
1997 ZJ 
 
Join Date: Dec 2006
Posts: 19,793
Those are the three items that cause it.one note, if you try to move the iac plunger yourself you've ruined it. Never move the plunger.

Check the throttle plate to make sure it's fully closing and clean the throttle body as well.

'97 zj 5.2, some stuff, some other suff, and some things that even work sometimes.

ratmonkey is offline  
post #3 of 11 Old 03-28-2012, 11:22 PM
mlhelfin
Registered User
1997 ZJ 
 
Join Date: Apr 2011
Location: Easton
Posts: 184
I replaced my IAC from Advanced Auto. About $70. New throttle body gasket @ about $3. At the front left corner of the throttle body is a set screw for the idle control. It doesn't need much to set it to a comfortable idle. I had to remove my TBI a couple of times and make minor increment adjustments 2 or 3 times to get it where it idled where I was comfortable with it. I idle at about 700 to 800 rpm's. Mark
mlhelfin is offline  
post #4 of 11 Old 03-29-2012, 04:11 AM
ratmonkey
R.I.P.
 
ratmonkey's Avatar
1997 ZJ 
 
Join Date: Dec 2006
Posts: 19,793
DO NOT ADJUST THAT SET SCREW!
It is NOT an idle adjust. It sets the throttle plate stop at the factory to account for machining variances. The idle is 100% computer controlled, you can not adjust it. Or rather you're not supposed to, you should fix the problem instead.

'97 zj 5.2, some stuff, some other suff, and some things that even work sometimes.

ratmonkey is offline  
post #5 of 11 Old 03-29-2012, 05:29 AM
ejschultz
Web Wheeler
 
ejschultz's Avatar
1997 ZJ 
 
Join Date: Feb 2010
Location: Crown Point
Posts: 3,419
It could be the TPS. Todd4198 had a bad TPS, bought a new one, and replaced it. Upon replacing it, his idle would jump to 2000 RPM in park. It sounded pretty bad changing from park to reverse or drive. He exchanged the TPS for another TPS and the issue was resolved. Apparently, he replaced his bad TPS (rough idle and crappy shifting) for a defective one (high RPMs in park). I want to say it's roughly $30 for the part. Make sure you pull the throttle body to change it. If not, you'll risk stripping the Torx that holds it into the throttle body. Ask me how I know...

97 ZJ - 5.2L, 242, 4" IRO lift w/short arms & adj. TBs, JKS Discos/BPEs, DT3000s, Aussie'd 44A, sliders, bumpers, bunch o' skids, 31" Duratracs on 15x8s
Build
ejschultz is offline  
post #6 of 11 Old 03-29-2012, 07:17 AM
cootertwo
Registered User
1997 XJ Cherokee 
 
Join Date: Jan 2012
Location: Labelle
Posts: 183
When I changed my IAC with one from discount auto, on start up, the idle went to around 3000, then slowly, a couple of minutes, it settled down to normal. It has to recalibrate itself or something.
cootertwo is offline  
post #7 of 11 Old 09-05-2012, 07:55 PM
RussMan
Registered User
 
Join Date: Feb 2011
Location: Marietta
Posts: 102
Excuse my noviceness but what is the TPS? My Jeep is doing this as well... it sits around 2.5K or so RPMs.

1997 Grand Cherokee Laredo I6, Running Strong at 176k! 2.35" lift running 31" Micky T's and a KOR rear bumper tire carrier.

"Dream as if you'll live forever, live as if you'll die today."
RussMan is offline  
post #8 of 11 Old 09-05-2012, 08:08 PM
no5son1962
Registered User
1995 ZJ 
 
Join Date: Aug 2010
Location: Colorado
Posts: 238
TPS Throttle Position Sensor. It is on the throttle body on the end of the throttle shaft. It can be tested by connecting an ohm meter and moving where the throttle shaft inserts. The ohm meter should change smoothly. If it jumps up and down there is a dead spot and it needs replacing.

95 ZJ 4.0L 3 inch Lift
99 XJ 4.0L 4 inch Lift
no5son1962 is offline  
post #9 of 11 Old 11-22-2015, 05:26 PM
gzrinyi
Registered User
 
Join Date: Nov 2015
Posts: 2
Just came across this old posting and found I have the same problem with the TPS (New TPS still has my car with a high idle and jumps up and down while in park.) You said to make sure and PULL the throttle body when you exchange the old with the new?? Please explain...
gzrinyi is offline  
post #10 of 11 Old 11-23-2015, 08:39 AM
kg6mov
Hears the voices
 
kg6mov's Avatar
1996 ZJ 
 
Join Date: Nov 2012
Location: Cupertino
Posts: 10,753
He was just saying to install the new sensor in the throttle body with it off the jeep, which would be easier. If you've already installed it then the new sensor is either bad or the TPS wasn't your problem. Did you disconnect the battery when replacing it to reset the PCM? Did you use a mopar sensor?

1996 ZJ Green Laredo V8, 2.5" OME and Bilsteins, 33's, Holes drilled in the roof.
1998 ZJ 5.9 - Junked
1984 F250, 460 BB, T19, work truck/future tow pig
1987 Mercedes 300D Turbo, the diesel daily, 30mpg in style

Quote:
Originally Posted by Texas ZJ1 View Post
I heard someone yell "mall crawler" from the back porch. I'll go see who said that. Be right back.
kg6mov is online now  
post #11 of 11 Old 11-24-2015, 01:55 PM
gzrinyi
Registered User
 
Join Date: Nov 2015
Posts: 2
High Idle

Thank you for getting back to me. Bought that new sensor online. It turned out to be bad. Went to the part store and purchased an OEM TPS with a lifetime warranty. disconnected the negative terminal and installed it no problem. Happy to report it is now running perfectly. Took the jeep out for a ride to run of some miles and let the PCM adjust to the new sensor and all is well. I appreciate your help!
gzrinyi is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the JeepForum.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.



Email Address:
OR

Log-in









Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Similar Threads
Thread Thread Starter Jeep Forums Replies Last Post
04 Grand Cherokee - high idle, won't come down 04cherokee ZJ Grand Cherokee Forum 8 05-28-2015 05:31 PM
96 Grand Cherokee won't idle Kalei2418 ZJ Grand Cherokee Forum 15 06-12-2014 07:49 PM
03 Cherokee Overlander HO High Idle after tune up marciad32 ZJ Grand Cherokee Forum 2 05-31-2009 09:03 AM
High idle after replacing 4.0 with one from Cherokee skidmark421 ZJ Grand Cherokee Forum 8 04-08-2009 10:05 PM
02 Grand Cherokee High Idle at start magnumbp ZJ Grand Cherokee Forum 1 08-24-2007 06:26 AM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome