Help Techs: Running Rich at Hot Startups - 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 > Help Techs: Running Rich at Hot Startups

Labor Day Sale!FS: 2007-2013 Jeep Wrangler "HALO" Angel Eye KitEngo winches available at www.rockridge4wd.com! Free shipp

Reply
Unread 06-01-2006, 04:57 AM   #1
Scott98GC
Registered User
 
Join Date: May 2005
Posts: 26
Help Techs: Running Rich at Hot Startups

My '98 GC 4 liter is running rich and stumbling at hot startups. It's okay if its only been shut off for a couple of minutes, but for longer periods or unless it's fully cooled off it will buck and stumble until it cleans itself out. If I start it and rev it a couple of times, it will clean out and run fine.
I don't want to go to the dealer and have him throw parts at it until a cure is found. I'm thinking it may be a sensor telling the computer that the engine is cold and therefore telling the engine to run too rich.
Any ideas?

Scott98GC is offline   Reply With Quote
Unread 06-01-2006, 06:13 AM   #2
greasefingers
Registered User
1994 ZJ 
 
Join Date: Sep 2003
Location: Northern VA, USA, NJ
Posts: 8,237
You would need to know if she storing any codes. Even then it is no guarantee that a sensor has not drifted. How old is your oxygen s sensor? I hear 1998 model has trouble retrieving codes by the manual method? You could try this: Extracting Fault Codes OBDII (with digital odometer display)
Newer (OBDII) models - Put the key into the ignition, push down the odometer reset button, then turn the key to RUN with your finger on the button - and then release the button. The odometer will go through 1111111 through 999999, and then display the car's serial number. It will then show the error codes
__________________
Cheers Steve

94 Black Laredo 4-Liter with QuadraTrac (42RE trans & NP249 TC) 200,000 + miles purchased new

88 Cherokee 2-door with 5speed manual 139K miles(deceased) purchased new
greasefingers is offline   Reply With Quote
Unread 06-01-2006, 06:37 AM   #3
Scott98GC
Registered User
 
Join Date: May 2005
Posts: 26
Thanks for the reply.
Mine won't display codes using the above method... what's the other method?
Scott98GC is offline   Reply With Quote
Unread 06-01-2006, 06:49 AM   #4
greasefingers
Registered User
1994 ZJ 
 
Join Date: Sep 2003
Location: Northern VA, USA, NJ
Posts: 8,237
Extracting Fault Codes:
Turn the ignition switch ON, OFF, ON, OFF, ON and observe the CHECK ENGINE LIGHT. The CHECK ENGINE LIGHT should begin to flash a series of codes. The flashes will be separated by short and long pauses. The long pauses separate the "ones" and "tens" positions, and each code from the next. A code 55 will be displayed at the end of the test.
__________________
Cheers Steve

94 Black Laredo 4-Liter with QuadraTrac (42RE trans & NP249 TC) 200,000 + miles purchased new

88 Cherokee 2-door with 5speed manual 139K miles(deceased) purchased new
greasefingers is offline   Reply With Quote
Unread 06-01-2006, 06:52 AM   #5
greasefingers
Registered User
1994 ZJ 
 
Join Date: Sep 2003
Location: Northern VA, USA, NJ
Posts: 8,237
You cycle the key to on/run and not start. Do it quickly.
__________________
Cheers Steve

94 Black Laredo 4-Liter with QuadraTrac (42RE trans & NP249 TC) 200,000 + miles purchased new

88 Cherokee 2-door with 5speed manual 139K miles(deceased) purchased new
greasefingers is offline   Reply With Quote
Unread 06-01-2006, 08:11 AM   #6
Scott98GC
Registered User
 
Join Date: May 2005
Posts: 26
I couldn't get it to go into code display mode. Mine must be one of those '98's that needs a code reader.
Scott98GC is offline   Reply With Quote
Unread 06-01-2006, 08:14 AM   #7
greasefingers
Registered User
1994 ZJ 
 
Join Date: Sep 2003
Location: Northern VA, USA, NJ
Posts: 8,237
Yea that seems to have been reported here a few times. I do not know why that model year is such a PITA.
__________________
Cheers Steve

94 Black Laredo 4-Liter with QuadraTrac (42RE trans & NP249 TC) 200,000 + miles purchased new

88 Cherokee 2-door with 5speed manual 139K miles(deceased) purchased new
greasefingers is offline   Reply With Quote
Unread 06-01-2006, 08:15 AM   #8
Scott98GC
Registered User
 
Join Date: May 2005
Posts: 26
It's got 100,000 miles on it now. I've only had it a year, but according to the previous owner's service record, it's never had a new O2 sensor.
Scott98GC is offline   Reply With Quote
Unread 06-01-2006, 08:17 AM   #9
greasefingers
Registered User
1994 ZJ 
 
Join Date: Sep 2003
Location: Northern VA, USA, NJ
Posts: 8,237
The v8 will also run rich if the ERG valve is stuck closed, as this dilutes the gas mixture in the cyl and lowers the combustion temp.

I would at the very least, pull a plug and examine the color.
__________________
Cheers Steve

94 Black Laredo 4-Liter with QuadraTrac (42RE trans & NP249 TC) 200,000 + miles purchased new

88 Cherokee 2-door with 5speed manual 139K miles(deceased) purchased new
greasefingers is offline   Reply With Quote
Unread 06-01-2006, 07:23 PM   #10
Scott98GC
Registered User
 
Join Date: May 2005
Posts: 26
Has anyone else had these symptoms?
Scott98GC is offline   Reply With Quote
Unread 06-01-2006, 08:05 PM   #11
GreenDean
Registered User
1995 ZJ 
 
Join Date: Feb 2005
Location: New Jersey, Exit 105
Posts: 1,918
Mine does this in the heat. I dont worry to much.. just the old engine blues.
GreenDean is offline   Reply With Quote
Reply
Thread Tools


Suggested Threads





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.