randomly the rpms will go real low, it doesnt throw a misfire code, well it isnt throwing a code at all... i have installed 2 new bosch o2 sensors and an IAC. What makes my 2000 xj 4.0 4wd die randomly. if something was wrong i would think it would set a code right? so what could be wrong with it.

 

there are a number of things that will cause it. could be fuel, ignition, or a sensor. you'll just have to eliminate these things one at a time when it dies. does it start right back up? does it have to set for a bit? it can be a difficult problem to nail down. good luck.

 

Mine is doing the same thing. I replaced both o2 sensors, the TPS, cleaned the throttle body and IAC. It helped a little but isn't perfect. I'm replacing the IAC and MAP sensor with new ones tomorrow. I'll let ya know if that solves my problem.

 

sweet man. well i have a lot of fuel pressure, i replaced both o2 sensors but i still get codes for the upstream sensor, guess i will replace it again! yes it starts right back up. can any other sensor tell the o2 to have too much volts? the check engine light comes on sometimes for the o2 sensor but does not come on when it is running like crap.

 

if you have a o2 sensor before and after the cat and you have replaced both sensors and till get the code... then replace the cat... that why they stick one before and after the cat to let us know how its working... well most vehicles now do them this way... idont know about jeeps cause mine doesnt but its old...

 

yeah that makes sense but the only code is for the sensor before the cat, i installed the magnaflow hiflow cat and a dynamax catback system, so i would hope my brand new cat is good. i ordered another upstream o2 sensor, i think that maybe the bosch ones i bought were junk, cause the rear one stopped throwing codes when i took the bosch out and put in the ntk sensor. also i still throw high voltage o2 codes with both unplugged!?

 

A couple peeps on jeepforum said they had same probs and changed out the CPS to fix it. This is my next move since the new IAC and MAP sensors didn't work. Must be something with the 2000's

 

Which o2 sensor? If it's the one behind the cat. then yeah it's the cat. that's bad. If the voltage coming out of your o2 sensor is high then your running rich. What is the voltage you have coming out of the o2's before and after the cat.?

 

its the one before the cat, the code is p0132 bank one sensor one voltage high. i am not getting codes for the second sensor, also my cat only has about 100 miles on it. so fafafofi, you are really thinking CPS, alright i will try it, getting desperate now. thanks man.

 

Now i am getting p0132 p0135 and p0138, getting 12 miles to the gallon, running terrible intermittently... this is getting frustrating, i am going to spend some time on it today and try to figure out this mystery!

 

I'm gonna work on mine today too. Haven't checked the fuel pressure so I'm gonna try that just to make sure and then tackle my CPS. I heard its a b*tch to get to so I'm not looking forward to it. Keep in touch so we can figure this thing out.

 

Hey fafafofi, do you think anyway has tried replacing the coil pack to fix this? I did the CPS on my 88 mj because i ripped the wires out when i pulled the trans, it was pretty easy, plus when its lifted, you wont have to jack up your jeep to get to it.

 

Tune up. Coil pack, plugs, wires, destributor cap, rotor, clean ur injection system, check ur fuel pressure, reset ur computer, pack up, and call it a day. lol.

 

Pretty sure it ended up being a burnt fuse for the o2 sensor, hasnt acted up sensed i replaced the fuse. It was in the PDB under the hood, i hope it is done acting up...

 

Try the TPS . Its $48 at autozone .Mine did the same thing and thats what it was . Good luck!