Nightsurfer

I have a 95 jeep cherokee 4.0 I pulled up to my brothers went in for about a half hour came out jeep wouldnt start ended up replacing the cps and it started but now it wont hardly run surging really hard pulled the codes and I am getting a code 25 I can disconect the ais and it dosnt effect the way it runs at all it ran perfect before i parked it.
Any ideas

4.3L XJ

Pull the battery terminals, touch them together and put them back. That will reset the computer. It will take it a few days to settle completely down after that

Nightsurfer

Thank you i will try that in the morning

Nightsurfer

Ok I tried reseting the computer got rid of the 25 code but still running like sh_t. Limped it home about 30 miles code didnt come back but its still doing the same thing not really a mis more kinda like a uuuuuuuuuuumm uuuuuuuuuuuum kinda thing I replaced the tps new plugs cap and rotor dont know what else to try any ideas?

4.3L XJ

What else have you done to the engine? When was the last time the O2 sensor was changed? If you floor board it does it run OK then?

Nightsurfer

Havnt tried to floor it dont know when o2 sensor was changed had it less than a year ran great untill i went to start it a brothers house other than that havnt had to do anything will take it out tomorrow and try flooring it and will let you know and thank you for your help.

Sloerolla

If it runs better when you put the pedal to the floor what does that mean...? My jeep is sometimes quitting on me and putting the pedal to the metal is what starts her up and seems to get her running well again .. I think its a similar issue to the op

4.3L XJ

That means that your O2 sensors are wearing out and need to be changed. When you floor it, the ECM runs richer than normal and compensates for a lean running condition

Sloerolla

why thankyou very much!!

Xjls1

If i remember right i had the same issue.and what fixed mine was taking throttle body off clean it really well and intake,it had a lot of carbon build up.after cleaning ran very smooth

Sloerolla

This was my first thing I did. Along with new fuel filter, plugs wires cap and rotor. Cleaned the one sensor that looked like a *****. But the condition has persisted. I bought a new sensor but it is not in. I imagine I will be doing the o2 sensors aa well..

tjwalker

I haven't seen any mention of verifying proper fuel pressure. It's one of the first things a shop tech. would do. I'm not saying that is the problem, but I am saying it is something that should be ruled in or out before delving in further.

For a 95, you need approximately 31 psi for the engine to run properly. Then disconnect the vacuum line leading to the pressure regulator and the pressure should jump to approximately 39 psi.

Test your way to a solution; don't throw parts at it.

Nightsurfer

ok I put fuel pressure tester on it getting about 41 pounds with key on when i start it needle jumps like crazy (needle dosnt stop jumping) and and you see a fluxuation that seems to corispond with motor surge any ideas?