i still haven't had any luck getting my 97 cherokee 4.0 to run right... it runs rough at idle and surges about +/-100 rpm. it also misses at higher rms. ive replace the plugs, wires, cap, rotor, iac, added injector cleaner, checked timing, checked for vacuum leaks, cussed at it and it still runs the same. not sure where to go from here. i have been trying to fix it over the last 6000 miles (4 months). any ideas??

Have you checked fuel filter?

new fuel filter put in a few weeks ago and runs the same... i did forget to mention that 3 times in the past 2 months it has hesitated, like it wanted to cut off but didn't. after i pushed the petal down it stopped bogging down and took off like it should. i hear a tapping/clicking noise as well. im thinking that whatever is making it run like crap is responsible for the noise. it is comming from somewhere in/very near the engine but i can seem to pinpoint it... any more thoughts??

Weird. This kinda sounds like when my cat. converter blew out. It actually clogged the entire exhaust system. The jeep ran like crap and wouldn't rev over 3K rpms. I'm assuming you have changed the CPS. What was the condition of the plugs when you changed them?

cps?? not sure what that is... actually i didn't replace the fuel filter on this jeep, it was my other car... my bad... the plugs looked like they should, i pulled them again yesterday and looked at them (after a few thousand miles) and they look like new...

i just got back from the parts store, checking on a price for a new fuel pump ($127) and on the way back, it bogged down and spudded a few times and then pick back up like it should. figures... would a fuel pump do make it idle bad, obviously if there is no gas... but it has been like this for a few thousand miles.

as far as higher rmps, it does just fine all the way up to 4500 and run strong all the way up. but if you have it in park or neutral and hold it on, say on 2000 rmps, you can kinda hear it stumble ever so slightly. and of course, at idle it still stumbles enough to make the jeep shake a little.

i have noticed that just before the connectioni into the main exhaust pipe to the cat, there is a dent... not sure what it is from, but i think it might be about 10%. i wouldn't think that this would create enough restriction to make it run bad.


Weird. This kinda sounds like when my cat. converter blew out. It actually clogged the entire exhaust system. The jeep ran like crap and wouldn't rev over 3K rpms. I'm assuming you have changed the CPS. What was the condition of the plugs when you changed them?

new fuel filter put in a few weeks ago and runs the same... i did forget to mention that 3 times in the past 2 months it has hesitated, like it wanted to cut off but didn't. after i pushed the petal down it stopped bogging down and took off like it should. i hear a tapping/clicking noise as well. im thinking that whatever is making it run like crap is responsible for the noise. it is comming from somewhere in/very near the engine but i can seem to pinpoint it... any more thoughts??


Have you had someone put a fuel pressure gauge on it and check fuel pressure appx. 39-48 lbs Usually the crankshaft sensor will kill it out sometimes it will start right back somestimes you have to let it cool. the fuel filter is mounted on the fuel pump assembly inside tank. have you cleaned the throttlebody, iac valve. Possibly a bad TPS sensor, throttle position sensor controls throttle position for driveability& idle
Dale jeepman600@sbcglobal.net :2cents:

I agree, check the fuel pressure. Your problem could be caused by crack in the pick up line on your fuel pump.. The crack in my line caused all of these irregular / seemingly unrelated problems.

I think I would replace the crank shaft position sensor first. There are a ton of posts in the jeep fourm about people having the same symptoms as you are having. Good luck keep us posted

myjeepsux420 might be right on the cat converter. Drill a hole in it to see if it is clogged. It will run a little better when you do this.
If not put a screw in the hole to fix it.

hey guys, thanks for the input... just the direction i have been needing... i will replace the CPS, check the fuel pressure, and put a hole in the cat ASAP and keep you posted! thanks a ton, cause i have been running out of things to do other than taking it somewhere and spending more than the jeep is worth to have it fixed! john

well i replaced the tps, map and O2 sensors, but the problem remains. i bought a new fuel pump assembly as well. i was going to replace the CPS and the TDC sensors and drill a hole in the cat before i do the fuel since it will be easier. Just how big of a hole do i need to drill for it to make a difference if it is clogged??

i bought a fuel pressure gauge from auto zone and check the pressure... it fluxuated between 45-52 extreamly rapidly. i think the rapid fluxuation was caused by motor vibrations. when you first turn the key, before cranking, the fuel pressure was 47psi. so i am guessing that the fuel pump is okay, so i am not going to replace it. any other ideas??

You have to love trouble shooting. An other thought (if you havn't done it already) is check your distributer for play.. There should be no side to side or up and down. Even a little bit of movement could cause problems like this.

yeah i checked that as well as making sure it was correctly bolted down. thanks!

i started a new thread so it would be easier to understand what all i have done and the suggestions that people have made. it is called somethings not right II....

Thanks a bunch yall!!