running rough, sometimes

hey guys, its been a while since ive posted on here. been busy with my '29 tudor sedan build recently. but now im having an issue with the xj thats kind of perplexing.

i had been at the shop all day 2 days ago and by the time i left it was dark and the temp had dropped considerably. got in my jeep and started it. was running weird like it wasnt running on all six cylinders. drove out onto the main road and she was real sluggish. the motor seamed almost out of balance. i would say almost sputtering but at a constant rythym with the rpm. got on the interstate and then it ran like a champ. passing cars effortlessly. seemed like when the motor warmed up it was fine.

then yesterday when i went to work she was running bad again. this time it was like that all the way to work so i was real tender footed with it. i noticed a good amount of smoke comming out of my tailpipe.

then when i left work it ran fine again. this time from the start.

any help figuring this one out?

95xj 4.0, fire power ignition kit(screaming demon coil, cap, rotor, live wires) plugs gapped to .065, rusty's tb spacer, cold air kit w/K&N, flowmaster, 2.5" exhaust from down pipe back. no cat. econo lift, M/T baja radials.

any ideas?

Do a plug reading. .065" is a bit much on the gap.

the firepower ignition kit is supposed to allow that much gap. how much gap can i run? the only reason i bought this kit in the first place is because when i got rid of my cat i could smell what i thought was unburnt fuel in the exhaust. the kit allowed for more gap which i thought would allow me to burn that unburnt fuel.

Try .050.

I think spec is .035, but with all your aftermarket ignition components, you should be able to run at least .050.

You've ran it for some time without problems at .065 though, have you not?

If so, then I doubt that is the problem... It sounds slightly fuel related. Check out the fuel filter, it is possible that some condensation gummed it up..

yeah ive been runnin at .065 for abgout 3 months. no problem until the other day. i will check into the fuel filter. havent changed it in a long time.

hey guys, i havent checked the fuel filter yet. partially because the problem stopped for a few days but on the way home tonight i had the problem again. i could tell it wasnt running right for the second i started it. there is different feeling when after i start the engine when im having this problem. i can feel the idle more. not like its faster idleing but more like i can feel every other stroke of the engine. another thing i noticed was the white smoke billowing out of my tail pipe. when i accelerate the motor almost seems like its missing.

weird thing is that when i pop the hood everything seems normal in there. when i go around back i can tell theres a problem. my exhaust note sounds like i have a very slow idle. and ofcourse there is that white smoke billowing out.

there is something i didnt tell you guys when i posted before. i had recently changed out my water pump only a few days before this problem started and now that i'm noticing this white smoke, im thinking it might be linked to that somehow. im not sure.

one more thing, when i was on the interstate either the problem dissappered or at high speed the problem isnt noticible.

thanks in advance.

White smoke indicates water is getting burned along with fuel. Usually w lot of white smoke indicates a blown head gasket, but since you changed water pumps I would check the seal of that pump. It may not have seated properly and is leaking.

how would an unseated water pump leak into the combution chamber?