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Problem today Not sure where to start??

1K views 26 replies 7 participants last post by  Hoser147 
#1 ·
Drove my 01 GC 6cly. today it was fine. Short trip thru $20 in the tank. This evening I went to leave got about a mile down the road, took off form stop and while gettin up to highway speed started missing. Throwing Code 0203 and 0303. Checked gas cap, Had new plugs and coil pack last summer. Any Idea's on where I should start? Kinda strange with 2 misfire codes. Thanks In Advance.
 
#5 ·
I agree. 20 bucks now days isn't much gas. Could have moisture in it or if the station just filled up it could have a lot of dirt in it. I would try to maybe empty is and get a high occtane and see how it does. Also should check coil pack just incase b/c things aren't made the same these days and don't always last like they should. Good luck though and let us know what you find
 
#7 ·
Grab some Lucas Oil injector cleaner and put some in ur tank. It will help with moisture and possibly help if there is dirt in the tank. It will also clean ur injectors an does a pretty good job.

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#10 ·
Added some seafoam this morning. Drove to work. Seems a little bettter. Went to Advance and had them do a scan on it. Showed injector 3 has a issue and missfire on cyl 3 / 5 /6 .......Really starting to suspect water or crappy fuel. Glad I just got $20 in gas and not a fillup. Plan now is to run it down and add the remainder of seafoam and run some premium thru her. Just like a woman!! LOL Any Idea's? Thanks all
 
#11 ·
Ran the old gas thru as much as possible put fresh Hi test in. Seems to be running rough yet. Found my old coil pack in the garage, just changed out cause of mileage. Plugs are from a year ago this spring. Thinking about throwing new plugs in or just changing out the coil pack and see what happens. Got the coil pack that is on there from advance when i done last tune up(didnt have much luck with their electrical parts on my dodge truck). Raining here so I figured I run it by you all. Thanks Again!!
 
#12 ·
Sometimes a trip to the dealer can save you a lot of money. I'm not saying all Jeep dealers are excellent, but sometimes it pays to go with the dealer. They should however be able to diagnose a bad injector or coil pack. Does sound related to getting crappy gas, however.
 
#14 ·
Do u see any worn vacuum lines? Specifically the ones coming out of the top of the valve cover? I had issues with my jeep ( the current LJ with the 4.0 I6 i have now) while in Moab. Similar problem. Got worse and worse. Jeep would run fine then struggle, miss fire and die. Right after some new gas at shell. I dropped the tank and all sorts of stuff. (injector cleaner, new gas, octane booster, pulled plugs)

Ended up finding a hole in the one vacuum line on the back of my valve cover the PO had tried to patch. Fixed it and the jeep has been fine since and feels more powerful. Apparently a vacuum line leak will cause a similar problem but if it's from the valve cover lines then it is more extreme and u will feel loss of power.

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#15 · (Edited)
I will check that out. Latest Scan shows open curcuit Cyl 3 and missfire on cyl 3. Thinkin bad gas and got a shot plug out of the deal. Believe if it were a coil I would have 2 cyl missfire as it has 3 coils. I think the bad gas caused multi missfires on different cyl last nite. Tonite with different fuel, I got nothing but #3 codes. Not sure on the open curcuit on #3??
 
#21 ·
You havent said anything about having changed the "Plug Wires" are they part of your "Coil Pack"? If not, try swapping them around and see if the problem moves to another cylinder (be sure to mark the wires on the known bad cylinders first so you can track them), you wont need a scanner just unplug the wire while its running and see if the engine misses more or not when you unplug them from each cylinder. Also, if you start the engine at night you will be able to see if the wires are arcing to ground rather than going to the plugs. Good Luck
 
#22 ·
^ what plug wires are referring to? Anyways. It sounds like the same thing I had happen to me. I had a misfire code on cyl 6. Changed coil pack and plugs, also oil change just to be safe. No change. Took it to a shop. Injector was getting power but no fuel. Somehow it got clogged at the tip. Probably the same problem for you.
 
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