2.4 sudden misfire

[EAGLIN]

I don’t even know what happened, one second the Jeep is running fine and the next it sounds like it actually wants to roll over and die. This started yesterday, my friends and I made a trip to Taco Bell and on the way I revel it out to 5k 2 or 3 times. The Jeep was running perfect, no CEL. Come back to the parking lot, still running great and as we’re eating in the car the idle slowly drops and gets really choppy while sitting at 500, then it drops under 500 and cuts out the engine. It showed a cylinder 4 misfire. So I limped it home for the night, she drove like a dog.

Now today I’ve tried diagnosing the issue and I’ve had it. Did the 2 main things, swapped the spark plug for the OEM style NGK Nickel spark plugs and swapped the upstream O2 sensor as well. No dice, still running like shit. Then I swapped the cyl 1 and 4 spark plug wires and I’m not 100% but the engine still runs like shit but it sounds a little different. But no CEL??!??

It putters around with absolutely 0 power, and wants to die but no CEL comes on. I can’t even verify if the misfire has migrated to cyl 1 from 4… I’ve had it with this stupid motor man holy.

I can’t wait to blow this thing up so I can engine swap it.

 

[macleanflood]

Clean the IAC?

IAC or Crankshaft Position Sensor.

-Mac

 

[EAGLIN]

Clean the IAC?

IAC or Crankshaft Position Sensor.

-Mac

Will do! I’ll try that tomorrow and update on if it worked or now. Thanks!

Krish

 

[EAGLIN]

Called my dad to let him know that it’s misfiring and he told me to do a coil pack test. Said that the coil pack has gone out twice on this Jeep before so I’m going to give that a whirl as wel.

 

[Jerry Bransford]

Does it run better when the engine is still cold or just as badly right after the first start of the day? As in before the engine starts warming up any at all? If so that can be caused by a bad Upstream O2 sensor.

 

[EAGLIN]

Does it run better when the engine is still cold or just as badly right after the first start of the day? As in before the engine starts warming up any at all? If so that can be caused by a bad Upstream O2 sensor.

It’s running bad from the cold start through warm. I don’t think it’s internals as it doesn’t burn a drop of oil nor coolant. I’m pretty sure it’s something electrical. Just a hunch. (Or Optimism so I don’t have to tear the engine apart)

 

[Jerry Bransford]

It’s running bad from the cold start through warm. I don’t think it’s internals as it doesn’t burn a drop of oil nor coolant. I’m pretty sure it’s something electrical. Just a hunch. (Or Optimism so I don’t have to tear the engine apart)

Could very well be the crankshaft position sensor then.

 

[EAGLIN]

Holy crap fellas, the shitbox is back in action! It was my ignition coil. But I went ahead and swapped the crank and cam sensors to NTK while I was at it.

 

[macleanflood]

What brand coil did you use? Or just swapped back to the original?

-Mac

 

[EAGLIN]

What brand coil did you use? Or just swapped back to the original?

-Mac

I was going to use Mopar, but I prefer NGK or NTK electrical, however they don’t have a coil pack for the tj2.4. So I saw advanced auto has lifetime warranty on the Carquest premium coil pack and it’s $50 cheaper than the Mopar one so I went with that. Mopar would have taken a week to get here too, was able to pick up the advanced auto one the same day!

 

[macleanflood]

Cool! Interesting to see how it works long term!

-Mac