1. Weird p0300 code

    So my 07 2 door jk 3.8.....it started with a p0301 misfire in cylinder 1, so I changed cylinder 1 spark plug.
    then it through p0303 misfire in cylinder 3, so I changed all of the spark plugs and the plug wires.

    then it through just a p0300 misfire in random cylinders.
    the Jeep runs fine, no sputtering or anything, it is a little choppy when I first start it.
    so I changed the coil pack.
    still throwing a p0300 misfire in random cylinders.
    but no other codes, no sputtering or running bad.

    what else could cause just a p0300 and no other codes?

    i have a suspicious feeling my shitty neighbor might have put something in my gas tank, could that cause it?

    i know I can try the cam shaft position sensor and the crank shaft position sensor, but if those were bad it would throw additional codes.
    mid it was a bad injector it would throw a misfire in that specific cylinder, but it isnt.

    any suggestions yall?

  2. #2
    Join Date
    Feb 2009
    Location
    Dayton Ohio Area
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    Re: Weird p0300 code

    What brand and PN spark plugs did you put in?

    Random codes can come from a weak battery or poor Corroded connections
    Misfire can be injectors, intake/vacuum leak bad plug


    Never look down on anyone unless you are helping them up - Jesse Jackson
    "Never look down on anybody unless you're helping him up" - Jesse Jackson

  3. #3

    Re: Weird p0300 code

    I don’t remember the brand of plugs or wires I used.
    But they are all brand new, same with the coil pack.

    if the injector was bad wouldn’t it misfire only on that cylinder with the bad injector?

    could sugar in my gas tank (or something like that) cause that?

    also, the Jeep isn’t running like it has a misfire, it’s just a little rough when I start it. But once it is running it is smooth unless the misfire is so slight that I don’t notice.

    if it was the crank or cam shaft sensor, it would throw other codes, right?
    and run like crap, had a bad cam shaft sensor in my pick up and it was a noticeable issues when driving.

    would a small amount of water getting in my intake cause this? Like maybe a table spoons worth?

    what kind of things would cause just that p0300 with no other codes and no noticeable misfire?

  4. #4
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    Weird p0300 code

    The P0300 is a random miss-fire code. You might not hear the misfire. Cam and crank sensors usually die or throw other codes.

    Plugs matter. Its big enough for me to ask. Cant tell you if you bought ones that are correct for your jeep.

    Did you reset/clear the codes since changing the plugs?

    You note wires and coil pack. What are the wires you replaced?


    Never look down on anyone unless you are helping them up - Jesse Jackson
    Last edited by JPNinPA; 06-22-2021 at 12:30 AM.
    "Never look down on anybody unless you're helping him up" - Jesse Jackson

  5. #5
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    Weird p0300 code

    Also sugar in the tank will clog the filter but does not disolve in gasoline. So you could check your fuel pressure.


    Never look down on anyone unless you are helping them up - Jesse Jackson
    "Never look down on anybody unless you're helping him up" - Jesse Jackson

  6. #6

    Re: Weird p0300 code

    I changed the spark plug wires. The plugs I got are the ones recommended for the vehicle, I just don’t recall the brand.

    i figured the crank and cam sensors would throw additional codes so that kinda rules those out, my next step was going to be checking the fuel system, the filter and pump and what not.

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