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The engine was misfiring just a few weeks ago but not enough for the CEL to come on. Big Zaddy starts and idles just fine and misfires around 35-45 mph. I purchased a set of NGK Iridium IX spark plugs and ENA ignition coils and took her on a test drive. Within a mile she started misfiring badly. This time we had an OBD II scanner and received codes P0300 for General Misfire.

My first test was to put the old coils back in and the misfiring stopped for two days, and now it’s back and strong enough to throw the same code. I’m purchasing OEM or maybe Mopar ignition coils and try again.

Do I need to install the coils in a particular order? None of the how to videos told me to do that, but perhaps that’s my problem. What do you think?
 

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Well, it occurred to me that I didn’t gap the spark plugs. Did that today and reinstalled everything, and this time in the correct firing order. Didn’t make a difference, I was misfiring before I left the neighborhood.

There’s nothing more to do but to work on Little Sister while I wait for the new NGK coils to arrive.
 

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Well, it occurred to me that I didn’t gap the spark plugs. Did that today and reinstalled everything, and this time in the correct firing order. Didn’t make a difference, I was misfiring before I left the neighborhood.

There’s nothing more to do but to work on Little Sister while I wait for the new NGK coils to arrive.
@Sngglebnny Good luck! Keep us updated.

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[Update] I might have effed up. I ordered brand new NGK ignition coils from PartsGeek.com, two days later I get my tracking info and it's not going to arrive until a week from now. I have this perfectly good weekend to do car maintenance and I'm not wasting it. I ordered some Duralast OEM ignition coils from Autozone and picked it up this afternoon.

The install was super easy since this is my 4th time taking everything apart. Put it back together and my engine starts misfiring from the jump! Shut it off and turned it back on a few times so the ODII could send the codes to my phone but then the phone died.

Ate some dinner and took the phone out to get the fault code. This time, I decided to check under the hood first and surprise surprise, coil #5 is not even plugged in. Plugged it in and drove around the neighborhood for a perfectly running engine, but as soon as I got back and started idling, my whole car started shaking.

What's that about? I'm going to unplug all the coils and replug them in the correct firing in the morning. Maybe that will fix things. Also, now my hood won't close all the way ????
 

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@Sngglebnny It's always something, isn't it? Let us know how it goes.

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[Update] I might have effed up. I ordered brand new NGK ignition coils from PartsGeek.com, two days later I get my tracking info and it's not going to arrive until a week from now. I have this perfectly good weekend to do car maintenance and I'm not wasting it. I ordered some Duralast OEM ignition coils from Autozone and picked it up this afternoon.

The install was super easy since this is my 4th time taking everything apart. Put it back together and my engine starts misfiring from the jump! Shut it off and turned it back on a few times so the ODII could send the codes to my phone but then the phone died.

Ate some dinner and took the phone out to get the fault code. This time, I decided to check under the hood first and surprise surprise, coil #5 is not even plugged in. Plugged it in and drove around the neighborhood for a perfectly running engine, but as soon as I got back and started idling, my whole car started shaking.

What's that about? I'm going to unplug all the coils and replug them in the correct firing in the morning. Maybe that will fix things. Also, now my hood won't close all the way ????
Sounds like there should be some DTC's in your EVIC if it's running that badly.

Do you see any? If so, what are they?

Do you have an OBD-II code scanner of some sort to pull codes?
 

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Discussion Starter #7
[Update] I plugged the ignition coils back in the correct firing order and had a nice strong ignition, idle, and drive for about 45 minutes and then Big Zaddy started misfiring again. We were halfway to our destination so we decided not to turn back and the misfiring continued pretty badly.

We shopped for about 2 hours and on the return trip home, the CEL went away and she didn’t misfire until we got back into the neighborhood. I ordered a new and better

OBDII sensor and am waiting for it to arrive. I’m going to continue in my tuneup and also check for other issues that could be throwing the same code as I go.
 

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[Update] I plugged the ignition coils back in the correct firing order and had a nice strong ignition, idle, and drive for about 45 minutes and then Big Zaddy started misfiring again. We were halfway to our destination so we decided not to turn back and the misfiring continued pretty badly.

We shopped for about 2 hours and on the return trip home, the CEL went away and she didn’t misfire until we got back into the neighborhood. I ordered a new and better

OBDII sensor and am waiting for it to arrive. I’m going to continue in my tuneup and also check for other issues that could be throwing the same code as I go.
@Sngglebnny That's odd behavior. Let us know what you find.

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Discussion Starter #9
I'm working on Big Zaddy again today. I'm moving to the next potential reason why I'm getting error code P2314 which is to test that the ignition coil is properly ground. I don't know what I'm doing but I found a video on Youtube that lead me to purchase a circuit tester/ test light and test the wiring to the ignition coil as well as Fuse 23.

I tested the wiring first and get no light on pin 3. According to the video, I should now test fuse 23. There is no fuse in #23. I go buy a fuse for 23 and it just wobbles in that slot and no power goes to it. I've just purchased access to the jeep commander manual on ChiltonDIY.com but they're having a technical issue and I can't see anything.

Is there a reason there is no fuse in #23?
 

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@Sngglebnny You did not need to pay for the Service Manual. If you had done a forum search you would have found links to free copies. Here is one: Commander Service Manual

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Discussion Starter #11
Thank you. When you spend several days searching for various pieces of information, sometimes you miss information that is right in front of you
 

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Thank you. When you spend several days searching for various pieces of information, sometimes you miss information that is right in front of you
You're welcome.

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