Hello, I have had some trouble tracing down some issues I have been having with my 2007 JKU with 165k miles on it. When I start it up, there is a solid check engine light and after about 30 seconds of running, the idle gets really rough and the check engine light starts blinking.
I have engine codes:
P0300 Multiple Cylinder Misfire
P2302 Ignition Coil 1 Secondary Circuit - Insufficient Ionization
So far I have replaced the plugs, wires, and coil pack all with mopar replacements. Hoping to not have to keep dumping money into it by simply trying to guess what it is. I also check/cleaned the grounds on the fenders and they seemed fine.
Not sure if its related, but the engine also has a small coolant leak at the intake manifold, and sounds like it might have a small exhaust leak at the headers at start up but always went away once warmed up. These have been around for a while but the codes are new.
Have you tried clearing the codes to see if they come right back? The po300 is most likely a fuel delivery problem. Without proper scan tools your just going to be throwing money at it.
I have access to a Snapon Scanner which I got the original codes from but haven't been able to use it to clear them (have to borrow it again). I will try that next, thanks.
I was able to clear the codes and they came right back within 18 seconds of running. I am using OBD Fusion app for monitoring for now. Are there any factory readings I can compare to?
Bump, anyone have a wiring diagram? I would like to try to test if I have any broken wires going to the coil pack or injectors before I blow money on a new PCM.
I ended up piecing together wiring diagrams sourced from jkfreaks and wranglerforum. Tested the wires between the pcm and the coil pack and they were good. Installed a new PCM and seems to have fixed the issue.
I've had similar issues with O2 related codes. After numerous rounds of replacing the sensors, I swapped in a new main engine wiring harness, thinking maybe it had been damaged (Mr. Nibbles anyone?). That offered no improvement.
Which led me to suspect an issue with he connector on the PCM or something within the PCM itself, since everything else had been replaced and checked and double-checked ad-nausea.
Yeah, after reading every forum post related to the two code combination, it seemed most time it was a bad PCM. After confirming wires between PCM and coil pack were good, I decided to do it. I even tore apart the PCM hoping to see something burned out I could replace but did not notice anything.
Put in new PCM. Codes p0300 and p2302 are gone for now.
Thank you very much folks.
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