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capncc
11-06-2019, 12:25 PM
2011 Rubicon
2.5 inch lift
35x12.50 NITTO ridge grapplers
5:13 gears
97500 miles
Superchips 91 octane tune

I was accelerating rating up the local toll road hill and she started shutting down , engine light comes on. Nurse it on home and DTC is PO301- cylinder 1 misfire. Replaced plugs, wires and coil pack cleared he code and test drove no problems. Drove to to next day itís ok, heading home got on the same toll road accelerating up the hill she shuts down again same code and now itís knocking and misfiring all the time. Time to get a compression check. Anyone have this problem?

Attenuator
11-06-2019, 02:04 PM
Injector issue?

Do a compression and a leakdown test, but if you replaced all the ignition parts, I'd look at injectors next.

Also, possibly look at the ignition wiring, trace it back along with the injector wiring. Look for damage.

Noble Woodsman
11-06-2019, 02:16 PM
I haven't had this issue with a jk yet, but there are a few things you can try if the compression looks okay...

Check vacuum pressure

Check fuel pressure

Swap the new coil, spark plug, and spark plug wire with another cylinder, reset codes and check if misfire moves to the new cylinder

Swap fuel injector with another cylinder and see if misfire moves

Replace Camshaft position sensor. I would try this last, because it's less likely and it's more of a part swapping approach instead of troubleshooting.

It may be a good idea to return the programming to stock first. I'm not sure if the 91 octane program would complicate the search.


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jeeeep
11-08-2019, 05:44 AM
i'd check the easy stuff 1st - plug, wire, spark from the coil pack

capncc
11-08-2019, 04:37 PM
Thanks for the feedback.


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cozdude
11-08-2019, 05:20 PM
2011 Rubicon
2.5 inch lift
35x12.50 NITTO ridge grapplers
5:13 gears
97500 miles
Superchips 91 octane tune

I was accelerating rating up the local toll road hill and she started shutting down , engine light comes on. Nurse it on home and DTC is PO301- cylinder 1 misfire. Replaced plugs, wires and coil pack cleared he code and test drove no problems. Drove to to next day itís ok, heading home got on the same toll road accelerating up the hill she shuts down again same code and now itís knocking and misfiring all the time. Time to get a compression check. Anyone have this problem?

Easiest thing to do would be to move the plug and wire to 2 different cylinders. If the misfire follows either one of those then thatís your issue. If it stays at cyl 1 then itís going to be an injector issue.

Do you have any other codes popping up as well?

capncc
11-09-2019, 02:49 AM
No other codes

capncc
11-10-2019, 11:26 PM
I did the compression test and here it is:
Cylinders 1,3,4,5 and 6 are 185 psi
Cylinder 2 was 30 psi and the plug electrode-had oil on it
Iím not sure why the code was PO301

Noble Woodsman
11-11-2019, 08:50 PM
I did the compression test and here it is:
Cylinders 1,3,4,5 and 6 are 185 psi
Cylinder 2 was 30 psi and the plug electrode-had oil on it
Iím not sure why the code was PO301

Wow. Any idea why compression is bad on cylinder 2 only?


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Snboarder113
11-11-2019, 09:10 PM
30 psi isnít really enough to run. You sure you got a good seal on the hose?
If itís actually at 30 you shouldíve had a hell of a lot more codes.


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