Idles rough at first, stalls once and then runs fine. - 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 > WJ Grand Cherokee Forum > Idles rough at first, stalls once and then runs fine.

Introducing MONSTALINERô UV Permanent DIY Roll On Bed LinePoison Spyder JK Body Mounted Tire CarrierBaseline 4x4 Lifetime Warranty 4340 Chromoly Axle Shaft Ki

Reply
Unread 12-12-2014, 09:10 AM   #1
casauall002
Registered User
 
Join Date: May 2010
Location: MO
Posts: 98
Idles rough at first, stalls once and then runs fine.

2002 4.7 HO V8 Overland

So, I know I have exhaust leaks as I can smell them and I have codes. Just donít have the money to get it fixed right now. Recently though, it started acting up and I wanted to see if there was something I could be checking or replacing myself. The mechanic said to start with the mass airflow sensor but I figured Iíd bring the question here first and see what everyone thinks before I start replacing things.

Say I start it up, it idles incredibly rough and bounces and you can hear the muffler making kindof a popping sound some times. From there, if I go and take off, there will be a spot where it kindof stalls even though Iím giving it gas and then the engine will do a quick rev in rpms and it will take off very quickly. After that, it runs fine with no issues including putting it in park and letting it idle. However, if I turn it off and then back on again, it usually doesnít idle well.

Any ideas?
Exhaust related
Muffler
Vacuum Lines
Fuel Pump
Fuel Filter
Mass Airflow Sensor
Other?

I appreciate the help!

casauall002 is offline   Reply With Quote Quick reply to this message
Unread 12-12-2014, 09:29 AM   #2
steve_80
Registered User
2000 WJ 
 
Join Date: Apr 2010
Location: Langley, BC
Posts: 226
IAC and/or TPS?

I replaced both of those (Mopar ones from Kolak) and now mine idles/drives/shifts like new.

Have you cleaned your Throttle Body and cleaned your sensors (IAC, can't clean TPS)?

http://www.wjjeeps.com/service/tbody.htm
steve_80 is offline   Reply With Quote Quick reply to this message
Unread 12-12-2014, 11:10 AM   #3
86cj74.2L
Web Wheeler
 
86cj74.2L's Avatar
2004 WJ 
 
Join Date: Jul 2006
Location: Stouchsburg, PA
Posts: 7,331
Vacuum leaks?
86cj74.2L is online now   Reply With Quote Quick reply to this message
Unread 12-12-2014, 04:52 PM   #4
casauall002
Registered User
 
Join Date: May 2010
Location: MO
Posts: 98
I know this may sound stupid but where is the throttle body? It actually has a brand new engine.

It does feel like a vacuum issue but I'm not sure how to determine it. I know if I smoke tested the thing, it would be pouring smoke from places. I've looked on youtube for an easy way to smoke test them but not really any easy ones. The shop will do it for like $70...Will that show vacuum leaks also? Would either of the above problems cause it to sputter and make the popping noise when idling in park?
casauall002 is offline   Reply With Quote Quick reply to this message
Unread 12-12-2014, 05:18 PM   #5
beachblu
Registered User
1999 WJ 
 
Join Date: Oct 2014
Location: WILSONVILLE, OR - Oregon
Posts: 4
Wj

IAC and/or TPS?

What is "IAC"??
beachblu is offline   Reply With Quote Quick reply to this message
Unread 12-12-2014, 07:18 PM   #6
86cj74.2L
Web Wheeler
 
86cj74.2L's Avatar
2004 WJ 
 
Join Date: Jul 2006
Location: Stouchsburg, PA
Posts: 7,331
I find vacuum leaks with a can of brake cleaner. Smoke tests to me are for troubleshooting problems with the EVAP system.
86cj74.2L is online now   Reply With Quote Quick reply to this message
Unread 12-14-2014, 04:01 PM   #7
steve_80
Registered User
2000 WJ 
 
Join Date: Apr 2010
Location: Langley, BC
Posts: 226
Quote:
Originally Posted by beachblu View Post
IAC and/or TPS?

What is "IAC"??
Idle Air Control... it's right next to the TPS (throttle position sensor) on the throttle body.

see here: [http://www.wjjeeps.com/service/tbody.htm
steve_80 is offline   Reply With Quote Quick reply to this message
Unread 12-15-2014, 09:18 AM   #8
casauall002
Registered User
 
Join Date: May 2010
Location: MO
Posts: 98
Quote:
Originally Posted by 86cj74.2L View Post
I find vacuum leaks with a can of brake cleaner. Smoke tests to me are for troubleshooting problems with the EVAP system.
What's the best method for using that and best place to start?
casauall002 is offline   Reply With Quote Quick reply to this message
Unread 01-13-2015, 02:01 PM   #9
casauall002
Registered User
 
Join Date: May 2010
Location: MO
Posts: 98
It's weird. It runs fine after that happens but I can turn it off for 5 seconds, turn it back on and the same problem again.
casauall002 is offline   Reply With Quote Quick reply to this message
Unread 01-15-2015, 11:02 AM   #10
beachblu
Registered User
1999 WJ 
 
Join Date: Oct 2014
Location: WILSONVILLE, OR - Oregon
Posts: 4
Steve80: first, my apologies for not responding to your excellent tips. As a long time hobby mechanic but novice WJ owner, I'm slowly catching on..
I followed the very informative links you provided and they will be tried. I once had a 5.0 Ford motor with a sticking "idle gate" that your comment brought out of my fading memory. I'm away from my trusty WJ for a few months now, but when back will followup and provide my "learnings" in another posting reply. Thanks again.
beachblu is offline   Reply With Quote Quick reply to this message
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.
Note: All free e-mails have been banned due to mis-use. (Yahoo, Gmail, Hotmail, etc.)
Don't have a non-free e-mail address? Click here for a solution: Manual Account Creation
Email Address:

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.


Thread Tools






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.