I've got a '99 4.0 that's been having some issues. Its been bucking and lurching and the motor sputters anytime I try to accelerate between 1500 and 2000 rpms. It gets worse if i give it more gas and better if I accelerate slowly, but goes away entirely above 2000 rpms. The check engine light is on, but it's not throwing any codes. It starts, idles, and shuts off without any issues at all.
I had just replaced the plug wires, and thought it could be a bad wire, but i spritzed some water on them and didn't have any arcing.

I saw a few posts similar, with problems ranging from crankshaft sensor to fuel filter. Is there anyway I can narrow down the problem? Is there anything else it might be? help!

 

If I remember right I think I read some where that a bad EGR valve can cause bucking on acceleration....but there's also the EGR solenoid.... Locate the EGR valve....see if you can push up the diaphragm with your fingers... sometimes they get stuck....

 

I didn't think a '99 had an EGR valve? Didn't those stop at 1990 or something?

 

How can the check engine light be on but not throwing any codes? If the light is on there is a code. Prob for a throttle positing sensor

 

im not really sure if it has one or not, I havent had my jeep very long, i just remember issues from my last vehicle.

 

just popped the hood, don't see an egr valve, guess im stuck in the 80's....

 

I checked the codes again, nothing. The ODO flashes through 000000 to 999999 like it should then returns to the mileage without doing anything else. Not a clue why.

 

its obd2 go to advance and have them scan 4 free

 

Ok, so I took it to Advance, and it's throwing a cylinder 3 misfire and downstream o2 sensor over volt code. from what i've read, the downstream 02 sensor doesn't do much other than tell you if the cat is bad. So, could a clogged cat be causing all of my issues?
Also, since that trip the problem has now gotten worse. It wont idle properly, and i don't think cylinder 3 is firing at all and the exhaust smells like gas. I've swapped plug wires and checked the distributor cap for arcing.
I've read that the 99's have issues with injector #3, could that be it?

 

c if cyl 3 is firing first, if it is then it is probably a stuck open injector on that cyl

 

As far as I know the No.3 injector issue is about heat soak. ie problems when a hot engine sits a while and is stared again.
Is the injector clicking? Put a long screwdriver on a good injector, put your ear on the end of the screwdriver listen to it click now do it on the suspect injector.
Been a couple of posts on how to clean an injector on this forum lately.

 

I would also check into the cat being clogged. My previous car had shifting problems where it would start bucking all crazy. I ended up swapping out the whole transmission and still had the problem. Later down the road I found out it had a clogged cat, so back pressure was going back into the motor and not letting it shift properly. After I had it replaced the car ran like a champ.

 

Finally got it figured out. Turned out it was a heat soak problem after all. The injector must have fixed itself, there were no issues with any of them so I didn't suspect this at first, until i went back and checked the plugs and saw the plug was fouled.
New plugs, cleaned injectors, new o-rings, runs like a champ!
Thanks for the help guys!