I have a 2003 jeep rubicon with straight 6 engine has been running great .Started it this morning and was idling very rough felt like a bad misfire took for short ride and engine cut out completly hitting the gas was able to get it running again did three times in a mile . Made it home and still idling rough with check engine light shut off and restarted about 10 minutes later and it is running g fine now. Any ideals what may have happened .
4.0 engine misfire
- Thread starter SteveR
- Start date
Is it throwing a check engine light? If so, have you scanned it for codes?
Sounds like a misfire to me, which could be a lot of things. A code would help a lot
Sounds like a misfire to me, which could be a lot of things. A code would help a lot
I just ordered a scanner so that I can check the code will get back to you thanksIs it throwing a check engine light? If so, have you scanned it for codes?
Sounds like a misfire to me, which could be a lot of things. A code would help a lot
Your TJ has a built-in scanner, all you have to do is turn the ignition switch on-off-on 3 times within 5 seconds and then leave it in the On position. Give the diagnostics time to work after leaving it in the On position, any stored DTCs (diagnostic trouble codes) will then display in the odometer. If there are no DTCs stored it will at least say 'Done' in the odometer display. Any DTCs will give a code like P1234.
Mine was acting very similar to what you are describing and kept throwing a P0301 cylinder 1 misfire. Tried checking tons of things to track it down (swapped plugs, leak down test, swap injectors, etc) with no luck as it was fine most of the time. The ignition coil rail finally failed completely one day leaving me on the side of the road. Swapped that out and no problems since.
Jeepn_Texas
TJ Enthusiast
Make sure you check the gap of your plugs!
When my coil rail died and I found evidence of arc-through near one of mounting bolts.
See picture, that is what it looks like when the high voltage finds it's way to the mounting bolt washer
Usually because the plug gap is too big, X2 by the way.
if the resistance is too high, high voltage will always seek the easiest path to ground!
It could be that bolt, or even another set of internal coil wires.
I could see this sparking to ground when running engine at night.
Also, clean all the gunk off the rail now and then.
I cut large inner tube washers to compress over the metal bolt bushing and washer.
the miss stopped for about 3 minutes... then the inner tube washer caught on fire.
Look at mounting bolt areas in the dark and see if you see little flashes.
I had a P0304 code which took me a few weeks to diagnose. Replaced all the spark plugs, fuel injectors, checked fuel injector wiring...to no avail. Finally sent me PCM to SIA Electronics who repaired my PCM (one of the solder points on the circuit board was broken). No problems since
Ok Thanks I guess I'll have to wait till it does it again to start checking things.
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