Ashewagon

It will start and run very smooth, very smooth, but when i start to drive it starts to jerk almost like it is misfiring. new wires, plugs, dist, this is why it is so confusing. it will not do it all the time, and when it warms up it stops and runs great. it is a 94 cherokee sport with a recently rebuilt motor, but it was doing it before it was rebuilt. i put it on an OB1 reader and the only code that came up was something like "electircal field malfunction" which only confused things more. please help, i would like to salvage some of my saturday.

thanks

jeep3200

Sounds like an issue with the cold start circuit.
On the rebuild were the temperature sensors replaced?
Was the throttle body cleaned?

armymedic120

what about the vaccuum tubing? mine did that, i went through and found a broken connection, fixed it, never did it since.

Willys55

loose ground on the battery or on the right side of the engine block, or get a new wife LOL....

Ashewagon

Thanks for the suggestions. the throttle body looks good. where is the cold crank circuit? have been over it dozens of times for vaccume leaks and have fixed them all. I know that i have a ground that is not connected well, but it is on a bolt stud, just not tightened. it is the ground that goes from the firewall on the right side to a bolt on the head. i am guessing this could be the problem because it does not do it all the time. maby just a loose connection throwing off the computer. Does this sound plausable? Thanks for your help

ZINGGG

Test you throttle position sensor. Replace if not getting the correct voltage. Also your
Crank position sensor could be going bad

The Rooster

on the 4.0 grounds are very important you need to tighten that up... and that would cause it to be good sometimes and fine other times... also make sure it is clean

F1Addict

Just to be clear, he's talking about the ground, not the Jeep. If your Jeep's too clean it won't start

freegdr

^^^ ditto

Ashewagon

Is the crank position sensor what reads the holes on the flywheel? and as far as a clean Jeep, that just wouldn't look right.

xjsnake

If it does it once or twice (almost a loss of power from the engine) and then it runs fine after that, look at the catalytic converter and O2 sensors.

Ashewagon

i had a 96 with that problem, so that is one of the first things I researched. that is not the problem. it will do it like every third time we drive it. reattached the lose ground wire, getting ready to take it out.

Gee oh Dee

Check fuel pressure if possible.

You can have enough fuel pressure to idle, but when asked for more hiccups can pop up...

Could be a clogged filter or something.

Killabrew

X2 on the o2 sensor. Up stream sensor I bet!

War Eagle

this...check all your grounds and terminal connections and clean them all too and then spray them with some kind of anti-corrosion spray, wd40 or pb blaster