stumbling idle after warmed up - Page 2 - 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 > stumbling idle after warmed up

SPARTAN LOCKERS are on sale BIG TIME at ROCKRIDGE 4WD!Introducing MONSTALINER™ UV Permanent DIY Roll On Bed LineG2 Disc Brake Conversion Kit for Jeep Wrangler YJ TJ LJ Ch

Reply
Unread 08-16-2013, 12:50 PM   #16
JaneLee
Registered User
1994 ZJ 
 
Join Date: Aug 2013
Location: Richmond, IN
Posts: 35
So the MAP sensor was bad but didn't completely fix the problem. got the RPM's to raise again to keep it idling right, and the new starting issue. i had another suggestion to check the o ring in the IAC, remove the o2 sensor to see if i may have done something else to the CAT i didn't notice, like maybe melting something inside to cause a blocking problem. so i'll be checking those soon as i can get my hands on the tools to do it. tonight or tomorrow. if y'all have any other suggestions they're greatly appreciated

JaneLee is offline   Reply With Quote
Unread 08-23-2013, 07:05 PM   #17
JaneLee
Registered User
1994 ZJ 
 
Join Date: Aug 2013
Location: Richmond, IN
Posts: 35
ok so i replaced the tps sensor and checked the cat and no difference. just barely a stumble out of gear and as soon as i put it in gear the rpm's drop from normal and it acts like it wants to die. checked the fuel pressure again and still running 33 psi. the injectors are all firing and leak checked them again, all fine. i am completely outta ideas. any more suggestions?
JaneLee is offline   Reply With Quote
Unread 08-24-2013, 09:41 AM   #18
ZeeJay1997
Registered User
1997 ZJ 
 
Join Date: Dec 2008
Location: Sweet Home, Alabama
Posts: 6,436
did you disconnect the battery when you changed sensors? need to let PCM relearn its fuel strategy


a stopped up cat will cause low manifold vacuum. most of the I6s run 15-18 in/hg at idle


another thought....this started when you changed the water pump and now you get an injector code. suspect damage to wiring harness on front of engine. a very small breech of the wiring insulation could be touching metal.
ZeeJay1997 is offline   Reply With Quote
Unread 08-24-2013, 11:48 AM   #19
JaneLee
Registered User
1994 ZJ 
 
Join Date: Aug 2013
Location: Richmond, IN
Posts: 35
only threw the injector codes when i disconnected them to check them out. after a few cycles of me checking things it stopped and only throws codes 12, 55. yes the bat was disconnected when sensors were changed. yes checked everything before replacing the sensors, got info from the dirty dozen jeep forum
JaneLee is offline   Reply With Quote
Unread 08-24-2013, 12:02 PM   #20
ZeeJay1997
Registered User
1997 ZJ 
 
Join Date: Dec 2008
Location: Sweet Home, Alabama
Posts: 6,436
so now your symptom is low idle?
ZeeJay1997 is offline   Reply With Quote
Unread 08-24-2013, 12:05 PM   #21
JaneLee
Registered User
1994 ZJ 
 
Join Date: Aug 2013
Location: Richmond, IN
Posts: 35
slight stumble in idle with normal rpm but rpm drops low in gear. about 5-600
JaneLee is offline   Reply With Quote
Unread 08-24-2013, 12:24 PM   #22
ZeeJay1997
Registered User
1997 ZJ 
 
Join Date: Dec 2008
Location: Sweet Home, Alabama
Posts: 6,436
when mine idles in gear the tach reads about 600, but if i look at it with a scanner it reads about 750

does it die if you try to drive it?
ZeeJay1997 is offline   Reply With Quote
Unread 08-24-2013, 12:29 PM   #23
JaneLee
Registered User
1994 ZJ 
 
Join Date: Aug 2013
Location: Richmond, IN
Posts: 35
after it goes into closed loop when it warms up, in gear, it wants to die and/or backfire. no power either. sputters and stumbles through a stoplight or stop sign. once i can get the rpms up near 1000 or above in gear it will get going but still hear that same intermittent stumble, same as i hear in P or N
JaneLee is offline   Reply With Quote
Unread 08-24-2013, 12:34 PM   #24
ZeeJay1997
Registered User
1997 ZJ 
 
Join Date: Dec 2008
Location: Sweet Home, Alabama
Posts: 6,436
sounds a lot like a weak coil or other ignition problem
ZeeJay1997 is offline   Reply With Quote
Unread 08-24-2013, 12:38 PM   #25
JaneLee
Registered User
1994 ZJ 
 
Join Date: Aug 2013
Location: Richmond, IN
Posts: 35
ok what is it, where is it, and what does it do?
JaneLee is offline   Reply With Quote
Unread 08-24-2013, 12:39 PM   #26
JaneLee
Registered User
1994 ZJ 
 
Join Date: Aug 2013
Location: Richmond, IN
Posts: 35
are you talking about the ignition coil? that's 1 whole piece to replace on mine isn't it?
JaneLee is offline   Reply With Quote
Unread 08-24-2013, 12:47 PM   #27
ZeeJay1997
Registered User
1997 ZJ 
 
Join Date: Dec 2008
Location: Sweet Home, Alabama
Posts: 6,436
the coil is mount on passenger side of block under alternator. it has a connector on it that is troublesome at times because the sockets get spread as mentioned in the.... hey i though you said you did the 12 things

my advise is to do a once over of your ignition system. pull the coil wire and look inside the boots for burning. same for plug wires. pull plugs and check for cracked insulators and proper gap. Pull cap and look for signed of arcing, crud, oil.
ZeeJay1997 is offline   Reply With Quote
Unread 08-24-2013, 12:58 PM   #28
JaneLee
Registered User
1994 ZJ 
 
Join Date: Aug 2013
Location: Richmond, IN
Posts: 35
yes i did do that. there isn't anything at all i can see wrong with any of the wires, plugs, boots, or under distributor cap itself. even the contacts look good. no condensation, corrosion etc
JaneLee is offline   Reply With Quote
Unread 08-24-2013, 01:13 PM   #29
Oldfrog
Web Wheeler
1997 ZJ 
 
Join Date: Feb 2008
Location: Louisiana/Texas
Posts: 3,886
Zeejay gave you good advice. I'll only add this :
The coil has a ground below it on the engine block. The PCM also grounds there, by the way. Remove that nut and the wire terminals. Then crawl under and take a wire brush to the grounding point and clean up the terminal ends. After scraping the crud away, spray it with electrical contact cleaner. Then remove the coil and inspect it for hair line cracks on the engine side. Pay attention to the wiring connector too, as Zeejay mentioned. It's a known problem area.

I've also found that the TPS and IAC wiring harness area can be a problem. Wiggle the wires while it's idling to see if the RPMs change, like mine did.
__________________
Cajun Recipes and Fishing tips

Words of wisdom, Posted by Zeejay:
"..it's not air, it is the opposite of air... suckage so to speak."

Stalling? Work through Zeejay's list
Oldfrog is offline   Reply With Quote
Unread 08-24-2013, 01:15 PM   #30
JaneLee
Registered User
1994 ZJ 
 
Join Date: Aug 2013
Location: Richmond, IN
Posts: 35
ok will try and take a look. thanks a bunch guys
JaneLee 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.