Okay I’m new here so sorry if posted in incorrect place. I have a 2008 jku that threw a 02 sensor code and a Cat code also was throwing a misfire code. I knew my exhaust was bad so I ordered all new cats and pipe all the way back including muffler. It’s all new. I also replaced all the 02 sensors at that time. For the misfire on cyl.#3 I replaced plugs wires and coil pack. It’s all new. Fired it up . Same rough idle as before. I pulled that number 3 plug, no gas was on it not dirty at all as all the other plugs were. I pulled the intake off and pulled the #3 injector and replaced it. I also took off the valve cover on that side to check the valve was opening and closing. No issues there no broken springs or anything , all is well there. Anyway I put it all together, fired it back up and same crappy idle. Now I have p0113 code a po303 code a po108 code a po123 code a po175 code and a po155 code. One of those is for fuel pressure. I have a leak on one of the injectors. Have to tear it down and fix that. Also I pulled the #3 plug again and it’s as clean as it was when I installed it. I’m at a loss right now. Any words of wisdom? Bad wire at the #3 injector?? Really frustrating.
2008 JK rough idle cannot drive stalls
- Thread starter Sigp320vtac1
- Start date
Yes I forgot to mention that I did do a reset. Not factory battery clamps either and I checked all the grounds I could under the hood.
You might have to check the intake manifold. That code is not in respect to an "02" sensor but to an O2 sensor. O2 is shorthand for oxygen in its diatomic molecular form, necessary for combustion. Rough idles are definitely related to combustion, either oxygen supply or fuel supply. You have addressed the potential ignition issues. You don't mention whether it is an upstream or downstream O2 sensor, the first is measuring what is being exhausted from the cylinders, while the second measures the effectiveness of the catalytic converter. With a rough idle, I would suspect the specific O2 sensor is up stream. If it's on the same bank as your misfiring cylinder, you might have to consider some more heroic work on the motor, removing and inspecting the intake manifold, and the air cleaner works. Another problem could be the fuel pump or the injection systems.
Upstream and downstream o2 sensors have been replaced . I think the key is that the #3 plug is pristine. No carbon soot or fuel on it after running the engine. Tells me the wiring may be bad to that injector. I have not take the actual intake off the engine just the plastic part of it. No leaks that I could find anywhere around it. I sprayed starting fluid around the intake to check for that . Did not find anything.
The pristine plug is definitely worth a careful investigation. I forgot to mention the throttle body might need cleaning. But the plug sounds like a higher priority datum.
Keep this thread going Sigp320vtac1, it’ll be interesting to know what the cure was. Diagnostics of all types are real helpful to most owners however frustrating at the time.
I came to the conclusion that it may possibly be the wiring harness for the fuel injectors may have a broken wire going to number 3 cyl. I ordered a new harness . Time will tell. I keep you all posted what happens when it arrives and is installed.
I’m just chipping in here and probably stating the obvious, but have you checked the continuity between Nō3 inj plug and the control unit, ‘cos that would confirm wether or not it was a break in the loom.
If it’s not you can check for a voltage at the plug when it’s running which is telling you if you’ve got an output from the control unit. I believe each inj has its own transistor which can be replaced. Keep going with it ‘cos you’ll get there
My 2015 kept throwing codes and was running pretty bad. The code are the same as yours. It had a bad injector and instead of just changing one, had all f them changed. Runs a hell of a lot better now!!!
Which brand of 02 sensors did you go with . Did a ton of research and not all 02 sensors work properly with the Jeep