chris015

00 grand cherokee limited, 4.0 167k miles.


has new coil pack,new champion plugs rc12pec5.


misfire on #1




well the pack is new.500 miles ago i changed out the plugs thinking it was that. Well i didnt replace those this time.

AFTER THIS IS DONE :

jeep runs rough at idle. and rpm's jump from 800 to 1100 at cold start AFTER it jumps to 2k for a normal cold start.then idles fine after its warm






Possible reason why its running rough :
My top rad hose has a bubble so i changed it out last week. While doing so i spilled a good portion of the fluid over the #1 plug. Well today before i installed the coil i pulled the plug and it had white residue on the electrode which im guess where it was wet? the jeep didnt run for 15 min or so after i changed the hose since i had to go pick a friend up in my other car. so maybe running the motor with a wet plug drying it out (while its skipping horribly). Should i change out that plug or is it ok?

rivercrazy

It sounds like the computer doesn't know what temp the motor/air is causing it to run rough when cold. Clean the plug with a wire brush and check/change your air intake temp sensor. If that doesn't do it check/change your temp sending unit and temp switch. Good luck and keep us posted!

rivercrazy

P.S. a good cleaning of your throttle body and all the sensors going into it with some carb cleaner (spray) will usually do wonders for these motors.

chris015

il do that. I still need to fix the rough running problem though.it runs rough enough you can feel it in the jeep