Where to start???? Plugs, Coil Pack, Injectors...

[alexbrown64]

As everyone has said, your engine light is coming on so check the codes. It will most likely say its the crank sensor or cam sensor. Get quality parts.
If it is one of those, still look at getting some new plugs and coil packs.

Cheers,

[Roler]

Check for codes, it's trying to tell you something.

One of the first steps with issues like this, is to clean up all your grounds,.it's free and normal maintenance. Many running issues can be solved.

The CPS is worth getting an OEM one. Aftermarket is known to cause issues, making you think you replaced it so it can't be that.

[Fishframe]

Codes a good start, but a head gasket or even worse a cracked head, can cause misfires and not generate any codes.

[Mace1]

#3 Cylinder miss fire.

Oils clean, coolants stable....

[Sobek]

If this were any other car I would just say to check the codes, and identify which cylinder or cylinders are misfiring. 99% of the time if it's a single cylinder misfire, it's usually spark related so it's often the coil. I don't know if these Jeeps' allow for it, but if you can swap the #3 coil over with another one, then run it again, you'll know if it's the coil that's at fault as the code will follow over to whatever cylinder you swapped it to. Simplest way to diagnose that...

Coils only last so long. Some types outlive their cars, others are regular replacement items. Rule it out first, swap it around with another if you can.

[Mace1]

The culprit.... stuffed insulator.



A new set of Champions installed and living the dream again.

Even ordered a new coilpack for the old girl to show her some loving.

[Fishframe]

I pull my plugs every service (I do my own basic ones - oil, oil filter, air filter, check fluids, belts, plugs ect...). Older Jeep’s like ours are tough on plugs so I like to keep them clean and gapped. Change them out every couple years or so.