studdering 4.0 WTF.......!

[tjrider]

I have a 2000 tj with the 4.0, and lately its been studdering and jerking under a hard pull. I changed the #1 o2 sensor, which helped for about 2 weeks. But now its doing it again. Doesn't matter if its on the highway or city. If I lug the motor, it will fall on its face. And I have no codes either. Any ideas. Or suggestions?.......

[sarge]

if it lugs under load it sound to me like ignition , how old is the cap and rotor , coil failing ???

[yellowjacket]

No dead cylinders i assume. How dirty was o2 sensor, and is new one dirtier than it seems it should be?

[tjrider]

It doesn't have a distributor, just a big coil pack. Wouldn't that throw a code though for a misfire? Its fine if I wind it out, just cruising and rolling starts will make it jump.

[tjrider]

It will idle rough sometimes in the morning for a few minutes

[GPER]

My 98 will idle rough some times and I wiggle the injector wires and it clears up.

[tjrider]

Checked for vacuum leak today, found nothing. Checked all the plugs, good even burn across all six, cleaned the entire throttle body. Still kickin. Anyone know how to test the coil packs? I'm thinkin its an ignition issue..... Just need to know how to check some things before I take it to scott

[tjrider]

Note to self.... Do NOT use E3 spark plugs in a distributorless 4.0. They don't like them!!!!!!

[WrenchMonkey]

Note to self.... Do NOT use E3 spark plugs in a distributorless 4.0. They don't like them!!!!!!

So that was it? Or you tried em and made it worse?

[eighty3bronco]

i was going to try the E3's and all the reviews that i read said that they were junk.... Did that fix your problem??? i have been fighting the same problem for a while.

[tjrider]

Coppertop told me to try changing them out, and I read some threads about them online. The 4.0s are very sensitive to what plugs you use. Went with a set of autolites and it runs like a champ. Sounds stronger too. So far everything is good

[eighty3bronco]

did you have any backfiring when it was having problems. my '99 cherokee will stumble for a few miles unless i go to WOT which i don't like to do since it likes gas then...

i think i might change out the plugs.

[tjrider]

Yes, when it would jerk and buck I could hear it in the exhaust pipe. If your running double prong plugs, that's probably your problem. It runs 100% better with better mpg too.