ok i filled up my 2000 xj with 40000 miles on it at shell with premium drove 35 miles to silver lake mi everything was fine started my jeep and went in the dunes drove around for about an hour and then stoped and shut off my jeep. when i started it up it was not firing on the 2 front and second from the rear cylinders. shut it back off and started it up and it was gone. this happened about 6 times that day. and then on the way home it started to misfire while i was driving and it wouldn't go away. had to get towed home.
i checked all the grounds, have no vacuum leaks, replaced the coil pack, checked the injectors they are all opening, then i put new fuel in and started it and it still misfired for about 40 seconds then cleared up and i drove it for 30 miles drove fine when i got back home it started to misfire in the driveway again and i shut it of and restarted it and it went away again. so I'm looking for any ideas

 

Any coolant in the oil or visa-versa?
Maybe you have the dreaded 0331 casting cylinder head...

 

could be injectors. mine #6...farthest back went out recently on my 2001 same situations. It just gets hot in there and they fail under that heat. Check engine light come on? If so get it read injectors will send codes.

 

no coolant in oil or oil in coolant, changed injectors on the cyilinders that are not firing

 

If a cylinder head wasn't replaced on it, then it is the 0331 casting. Did you replace the plugs when you did the coil packs? Is it throwing a check engine light? If it is throwing a light, did the light blink while driving at all? Was the Jeep regularly serviced and has it been sitting at all? If you did pull the plugs, what did they look like?

 

Does your exhaust smell like Budweiser? I think Bill and Dan might have added some funny additives to your gas tank in the middle of the night to slow you down.

 

Oh you Grand Haven guys...LOL

 

i did not change the plugs they looked fine but they are fancy e3 platinum things, the light is on and if you drive it the light flashes. it hasn't sat and it has always been serviced regularly.

 

Okay, the light flashing is indicating a lean condition...which means that it's got too much air and not enough fuel. So the injectors may be your culprit. Take it to an advance auto or auto zone and have them scan it. I would do it for you with my scan tool, but I'm too far away. Have you run the vehicle since installing the new injectors?

 

they may have but ask them who didnt get stuck at silver i think ill add the pics of them stuck but there are so meny it wood take way to long

 

but it gos away and runs fine for hours then comes back, ill scan it tommorrow just have to get the scaner from my work

 

i have ran it after the injectors and its still doing the same thing some times it has the mis always on the same cyilinders and sometimes its fine

 

You may get an injector code, but you may also get an air flow code too...may be your MAP or MAF sensors. Just remember that even if the light goes away, the problem still remains. I'm new to Jeeps, so I don't even know if they have a MAF sensor or not. Some of the veterans will chime in too.

Edit: Reading up on some sources, this sounds like it could be the Manifold Absolute Pressure sensor. Your Jeep does not have a Mass Airflow Sensor...good 'ol research.

 

mine was just like that when an injector went...it was the #6. and had the same check light issue. get soem codes ran it will tell you what number cylinder and everything if it is an injector.

I could go for days without and issue then all the sudden it would be back

 

thanks for the help so far ill scan it in the morning and post the codes