P0301 misfire

Csdrtr

Csdrtr

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Joined
Mar 22, 2021
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5
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Fort Worth TX
Hey guys I’m new here. So I have a 2007 Jeep Sahara. It’s got a p0301 code that is active which indicates a cylinder 1 misfire. I’ve replaced spark plugs, spark plug wires, ignition coil pack and a fuel injector for the #1 cylinder but nothing has fixed it. Has anyone else had this issue? If so do you have any recommendations?
 
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Csdrtr said:
Hey guys I’m new here. So I have a 2007 Jeep Sahara. It’s got a p0301 code that is active which indicates a cylinder 1 misfire. I’ve replaced spark plugs, spark plug wires, ignition coil pack and a fuel injector for the #1 cylinder but nothing has fixed it. Has anyone else had this issue? If so do you have any recommendations?
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Why not use your $5,000 computer analyzer to diagnose the problem, like any mechanic would do?
 
I just went through this - see my other post. I replace plugs, wires, and coil pack, and the P0300 code (general misfire) went away, but i got a code showing fuel injector circuit on no. 2. I replace the fuel injector with a remanufactured OEM injector and solved it - but I also read that for general misfire, you might look at changing the crankshaft (not camshaft) position sensor - easy and about $20 so why not. Also, check the wiring harness to the injectors for any cuts, or loose connections at the injectors, etc. (break and remake all the connections) Also, for general misfire, check the ground for the computer module - mine were corroded and I cleaned them up.


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2008 JK 3.8 2 door. my wife was headed home tonight from school - check engine light came on, running rough. checked oil - low about a quart. also topped up coolant. transmission oil level was full. I have a JScan and plan to check for codes in the morning. I also have plugs and wires...
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did not need a $5000 analyzer - the JScan app and a blue tooth OBD2 scanner worked great - and not expensive.
 
Csdrtr said:
Hey guys I’m new here. So I have a 2007 Jeep Sahara. It’s got a p0301 code that is active which indicates a cylinder 1 misfire. I’ve replaced spark plugs, spark plug wires, ignition coil pack and a fuel injector for the #1 cylinder but nothing has fixed it. Has anyone else had this issue? If so do you have any recommendations?
Click to expand...

Have any luck fixing this?
 
Hey guys sorry for the late update. I fixed the p0301 code, turned out to be the PCV valve. However I am still getting a p0300 code and it’s better than it was before I changed the PCV valve but still idling rough. Since I’ve replaced the PCV valve, I have replaced the EGR valve, camshaft and crankshaft positioning sensors, and now I’m replacing the 02 sensors.
 
After you replace the o2's you might need to do a reset, it will help the ECM do a relearn.

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Hey guys, thanks for all the help! The 02 sensors seem to have done the trick. It’s not throwing any more misfire codes. But I think the misfire did a number on the catalytic converters. I’m now getting p0430 and p0420. I’ve had that misfire over a year
 
Csdrtr said:
Hey guys, thanks for all the help! The 02 sensors seem to have done the trick. It’s not throwing any more misfire codes. But I think the misfire did a number on the catalytic converters. I’m now getting p0430 and p0420. I’ve had that misfire over a year
Click to expand...

Is that for the downstream o2's?
 
Hey, How is the troubleshooting going? I am chasing the p0300 right now. I Replaced the ignition system from coil pack to wires to spark plugs. Crank position sensor just a few minutes ago, and still no avail. I am thinking that its the 02 sensors because I had it leaking exhaust for so long. Do you have any advice on whether I should try the injectors first, or just go straight to 02 sensors. Also, the drivers side of my spark plugs are dirty and carbon-ey but passenger were fine, leads me to think O2 sensor... Anyway, good luck to you! Post what you find!
 
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