i have a 98 cherokee with an 01 engine...(inl6)..it starts fine,and runs fine for a few minutes,until it comes up to temperature.Then it will not go and starts backfiring(popping) through the breather.Continues to run but acts like it is flooding out.If i pull over and shut it off for maybe 30 seconds or so it will run fine again for just a few minutes and then start over, and after a few pops she takes off like a bat out of h*ll.I have replaced the spark plugs and wires, dist. cap and rotor, and both o2 censors. but i really can figure this out i have tried with mechanics but they look at me like im nuts. PLEASE if u have any idea, links, etc.

 

heres some possibilitys ...injector timing is wrong..valves need adjusted... engine timing is wrong.. those might be some things you want to look into but i dont know everything but this is what i have for advice so id wait till some other people post on this

 

thank you for takin ur time to point me in the right direction i have tried for so long and nothing...mind u it only does it when my check engine light turns off

 

how mechanicaly inclined are you if your good with it id check the valve lash and the timing and the injectors timing and injectors themselfs they might be skipping /missing if you arent good with mechanics and just like to offroad and stuff id take it to a garage and see what they can do..

 

well im not a pro but i can hold my own..i need to do my valve cover hear soon so im going to check my valves and adjust if needed. as for the injectors i ahve never messed with that.. how would i check that?

 

Injector timing is automatically done by the Crank Position Sensor. Ignition timing is done automatically by the Cam Position Sensor. You really can't screw either of these up or adjust them. One of the sensors could be bad but, normally don't cause your problem. If either of these sensors is bad, the Jeep just won't run. Your problem sounds like a massive vacuum leak or a problem with the temperature sensor - the temp. sensor for the Fuel Injection Computer, that is.
My questio is this, how much of this motor is the 2001 and how much is the original 98 motor. Hopefully, you used the bare block and head from the 01 and the rest is 98. That's th only way I could see this engine swap working.

 

well im pretty sure thats what it is.. i want to check my block any markings that will tell me its an 01?

 

that is what i was thinking because the 2000 and up had the coil on plug. this could be a bad crank shaft position sensor. but the ignition on the 98 style is still a cap and rotor so his timing could still be out of whack. check for vacuum leaks.

 

yea i heard i should check all my intake manifold for loose bolts...does that happen often?

 

I'm going out on a limb and saying its not timing or valves since the thing runs fine till it heats up. I would bet its a temp issue so I would start with the water temp sensor that is on the back of the head on the drivers side. If its a wrangler motor its not going to have this sensor, but your motor needs it to run.