'04 WJ Runs Rough at Startup - 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 > '04 WJ Runs Rough at Startup

Save 15% in XT's Pre-Black Friday Event!FS: Wranger BRIGHT License Plate LED! Just $3! Great valueIntroducing MONSTALINER™ UV Permanent DIY Roll On Bed Line

Reply
Unread 12-22-2013, 08:43 AM   #1
specia1k
Registered User
2004 WJ 
 
Join Date: Sep 2011
Location: Jacksonville, FL
Posts: 331
Wj '04 WJ Runs Rough at Startup

My daughters '04 WJ Sport 4.0 occasionally when started will run super rough. She says it feels like it's going to explode. Most of the time you can turn it off, re-start it and it goes away. I suggested she put a can of Seafoam in the fuel to clean injectors. The spark plugs were replaced a couple years ago. Otherwise the WJ runs well. She just came back from college for XMAS and got 400+ miles to a tankful, so the engine is running efficiently as it has in the past.

Thoughts?

__________________
2004 Jeep Grand Cherokee Limited 2x4 4.0L
2002 Jeep Grand Cherokee Sport 2x4 4.0L
1998 Jeep Grand Cherokee Laredo 2x4 4.0L
"Three daughters, three Jeeps"
specia1k is offline   Reply With Quote Quick reply to this message
Unread 12-22-2013, 09:38 AM   #2
doityourselfMM
Senior Member
 
doityourselfMM's Avatar
1999 WJ 
 
Join Date: Dec 2010
Location: manassas, va
Posts: 787
I suspect the problem is electrical. If it was mechanical, the problem would most likely persist. Since turning it off and restarting seems to 'clear' the problem, I don't think it's plugs.

I had a similar idle fluctuation issue. Turning it off and restarting always smoothed the idle out, to a nice flat 550 rpm. I removed the throttle assembly and cleaned. Particularly the IAC valve. So far, so good.

Try the simple (and inexpensive) remedies first. It would probably be wise to install a new throttle gasket after cleaning. Don't over torque (and snap) the 4 bolts.

And don't rule out the Crank Sensor.
doityourselfMM is offline   Reply With Quote Quick reply to this message
Unread 12-22-2013, 09:50 AM   #3
Upside
Registered User
2002 WJ 
 
Join Date: Dec 2004
Location: Irvine, CA
Posts: 817
My 2002 4.0 does this on occasion. I've replaced my battery cables to solve a slow cranking issue and cleaned the intake. When the misfire happens it seems like either an injector or a plug isn't firing. I haven't checked the resistance on the coil or injectors since it hasn't happened in a while. I do run MMO in the tank now for better fuel mileage so maybe it was a sticking injector.

My driving is very consistent and I get 2 MPG better with the MMO. The mileage is apparently dependent on your specific Jeep and the fuel available in your area, some see an increase and others do not. I think the MMO just allows the computer to run more timing on our California fuel.
Upside 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.