OK everyone Im stumped!? I drive a 2000 jeep cherokee xj with the straight six.... Ive been having trouble figuring out what the hells wrong..... Its been missing and lossing power pretty bad. It will drop down to about 200 rpm, then jump up to about 1100rpm... I cleaned the IAC sensor, replaced the TPS sensor KINDA! ( DONT BUY FROM AUTOZONE PART CAME BROKEN!) took it back and went to junk yard and bought a used one from there.... I replaced the MAP sensor and cleaned the throttle body.... My mechanic mentioned that jeeps are bad for crankshaft sensors, so i replaced it. Needed about 3 feet of rachet extentions to get to it but mananged to get it out and replaced. I also replaced the O2 sensors two different times! thats what the codes were for.. at first I put boush sensors in and was told there junk. so i went to NGK... The light never went off.... I've changed the plugs to champion coppers, and cleaned all of my electrical connections. OBD codes still being thrown... My guess is the camshaft sensor now, First becasue of the miss, and second maybe the timmings off a hair?

Any ideas... Im a kid could use some good advice

 

It could be the camshaft sensor, but from all the research I have done on those it generally throws out it's own code if it is bad. If you are intent on replacing it, it is really easy to. Just replaced mine. Took 3 minutes and a Phillips head screwdriver. Just know that if you get one from autozone or Napa, they call it a "pickup coil". $53 part.

 

Guess on your OBDII, after something is fixed it takes a while for the light to go off. The timing is set by the PCM, no adjustment. I'm no real help on your miss. Cap & rotor? Your fuel pressure is 49 pounds I think. I might try some fuel additive/injector cleaner.

 

What are the codes?

 

Might want to check the wires from the 02 sensor.

 

Sorry I havent posted in a while been busy working.... All the codes it was throwing were 02 sensors and i think they said sensor high voltage bank 1 sensor 2 and bank 2 sensor 2.... There was four codes but there all sensors i think... I erased the codes, about 7 miles later there back on and throwing the same codes

 

X2

 

This is what i pulled... (PO135.02 SENSOR HEATER CIRCUIT BANK 1 SENSOR 1), (PO141.02 SENSOR HEATER CIRCUIT BANK 1 SENSOR 2), (PO138.02 SENSOR CIRCUIT HIGH VOLTAGE BANK 1 SENSOR 2).... Im pretty sure those are all for O2 sensors... I think im gunna go and change the camshaft sensor if its that easy. Question what is the PCM is that a sensor?

 

No, that's your computer! Power Control Module

OK, I'm no wizard here, but I think there is a relay, (and a circuit), for a heater in the O2 sensor.

 

Sorry Im a Noobie lol! Im still in highschool and this is my first rig ... Also I just went out to move my jeep and i started it up and it was running at about 700 RPm with no mis... which is awsome because its been idling at about 400 RPM .... But my question is how long will it stay normal or as what i think is normal?

 

Hey! It's all good.. I'm just learning myself. So it's now running fine, just throwing codes? The O2 sensor has a heater deal so it reads when its cold. Helps smog probably. Has a relay triggered by the PCM, On my 90 it's one of 4 on the fender under the hood.

http://www.jeep4x4center.com/knowledge-base/index.htm

 

Well...I'm a little overwhelmed. You might check fuse #17. Also in that link, in wiring diagrams , 8W 10-2 shows the location of the relays in the power distribution center. I guess they can be swapped, like, take the one for the AC and try it for the O2. It's "powertrain" btw

I guess that O2 sensor heater wire caries a bit of current. I'd probably take a good look at it's wire and connector as well as the fuse and relay.

You can see it better on that link, But here's how we "cut" & "paste" in Bedrock!

Also fuse #10 might provide power for the two O2 sensor relays.

 

Okay guys heres a question! Was just driving home bout ten minutes ago and it puttered out and died..... Started up drove bout two miles and almost died again but this time it sounded like it was back firing in the motor.... Any ideas and have been busy working lately so i havent checked the fuses or relays yet.... If you guys have any ideas let me know.

Thanks

 

my trucks been doing the same thing. i already changed the fuel pump and the crank sensor. i just threw down on a new auto shutdown relay and fuse to see if that will do it.

 

This is kinda off the wall, but since I had it happen to me... Here goes...
Check the wiring that goes to the rear O2 sensor. If it is hanging down near the driveshaft in a position that it might contact the driveshaft while driving, check all the insulation, wrap it, and tie it up out of the way. If the driveshaft grounds out the O2 heater circut - It will either blow the PCM fuse, or cause all kinds of glitchy behavior.
Ask me how I know...