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99 Jeep Grand Cherokee Power Cuts out when Driving


newtojeeps88
02-10-2013, 11:44 AM
1999 Jeep Grand Cherokee Laredo, 4.0 in line 6 Cyl misfires when driving. I bought this about 2 months ago (200,000 miles), and when i first got it it was acting like it was misfiring when driving above 60 mph( did get codes P0301 cyl 1 misfire, and P1391 CPS) . it started to act the same way just driving in my small town. so i ended up changing the ignition coil pack and changing spark plugs, i also replaced the CPS (camshaft position sensor). and was still acting the same way. I located a TSB that said there might be a carbon build up problem preventing valves from rotating and seating. so I used seafoam and clean up the Top, and drove it in low gear at 4500 rpm for 15 seconds or so 6 times.. initially when doing this it was cutting out (jerking) when rpms got up there. after doing this twice with about 3 weeks in between never had a problem in town with it acting up running like it should from what i can tell.. Then i took a road trip, and a 60 mph was fine, 70 mph it was fine.. so i thought it fixed the issue and all good.. but about an hour into the drive it started acting up again.. unexpectedly cutting out for a second here and there, and usually when going up hill, and when got to destination about another 40 minutes, coming to a stop light i noticed it when stopping it was running pretty rough like it wanted to die out but never actually did. never got any more check engine lights either. I'm kinda at a loss at what the issue might be, and what i need to do to fix it as i really like the vehicle, any and all help you can offer would be appreciated.

hundahunta
02-13-2013, 12:11 AM
look at the back of the engine there might be a stud sticking out shorting the harness..

newtojeeps88
02-13-2013, 12:23 AM
Thanks i kinda wondered if there might be a short somewhere, but didn't have a clue where to even start looking for one, as i've read other posts this referred to similar issues, which harness (if more then one) should i be checking?

I am also planning on changing out the Crankshaft position sensor, and Throttle position sensor just to see if that helps.. but any other suggestions and / or experience with this same issue with possible fixes is appreciated..

hundahunta
02-14-2013, 12:34 AM
I would try the crank sensor before the tps

newtojeeps88
02-23-2013, 07:16 PM
well i believe the problem is solved... I changed out the fluids, and decided to tackle changing the Crank Position Sensor today.. as i checked out the Sensor from above.. i was able to reach down far enough to touch it, and i found it moved around pretty easy, had some pay to it and the bolt apparently was not tightened up all the way.. so i still changed it out and tightened up the bolt so it didn't move.. and there you go.. took it for a drive no issues as described in my original post.. will take it on a road trip tomorrow to see if it work fine on the road.. fingers crossed that its all fixed.. damn something simple.. well thanks for all the help and will post back how the road trip goes.. have a good weekend!!

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