bakulatp

I also had a P0300 code randomly for months... changed wires, spark plugs, and coil to no avail. The engine's hesitation got worse until it threw a specific cylinder code.

https://www.jk-forum.com/forums/stoc...5/#post3999937

Still to this day the jeep is driving great.

07 Rescue Green

Well I went with Granatelli wires and the Screamin Demon coil, code cleared for a week or so and now it's back. It idles rough for the first 30 seconds or so then smooths out. I'm taking it in this sat., hate the check engine light.

07 Rescue Green

Here is an update: I took it in to my local guy (not a jeep dealer), he pulled #1 plug which showed that cyl was running rich and swapped it with #4 which was good. I also filled up at a name brand station. 3 days later the check engine light is back on. He pulls the plug out of #1 and it is dark like it's running rich so he says fuel injector must be dribbling a bit in cyl #1 (it runs great after the initial 30 seconds or so). Replaced the injector in #1 and 2 miles down the road the MIL light is on again. He's doing some research to see what else to look at. I'm about ready to trade it in.

bakulatp

Please keep us updated.

I swapped #4 and 6's fuel injectors after tripping a misfire code awhile ago. Cleaned everything and problem was gone until a few weeks ago when I started the jeep after work and sitting in single digit weather. The hesitation and sputtering came back but no code has tripped yet.

07 Rescue Green

Here is an update, replaced #1 fuel injector, P0301 came back within 5 miles, the shop put some test equipment on the injector signal and spark plug wire. Definitely a spark issue, now remember I've already put new plugs, wires and a coil on it. We are going to throw a cam position sensor and crank position sensor at it on Friday (that's when the parts come in). If that doesn't fix it I'm guessing ECM? Has anyone else had this issue? It only does it immediately after startup and clears up within a minute, normally less than 30 seconds then it runs smooth until you shut it down again.

07 Rescue Green

Well, the cam sensor and crank sensor did not fix the problem. I really don't know where to go from here. ECU? Trade it in? If I could break even on it I just might do it. I love driving it, took the front panels off yesterday, it was awesome. Pulling my hair out here.

ronjenx

How much of the list in post 2 have you done?

07 Rescue Green

Ronjenx, I printed out a copy of your list and gave it to my mechanic, he ruled out plugs, wires and coil since I had already changed them, also the fuel system as it's consistently only on cyl. #1, after he replaced #1 injector he connected some test equipment to the jeep and said the injector signals were good but he could see a breakdown in the ignition signals, said the crank sensor and cam sensor signals looked irregular. Replaced those with no improvement. I know the ASD relay circuit was not checked. We talked about possible engine mechanical issues but since it clears up within 30 seconds or so he ruled that out as well. We also discussed engine accessories and how they could possibly drag the engine speed down but since it's an obvious miss for that 30 seconds or so he ruled that out as well. I'm guessing PCM. I found a "reset" procedure on here somewhere so I'm going to try that today. It'll probably go to the dealer to be diagnosed and if they can't figure it out I'll be getting rid of it. Thanks!

bakulatp

I also replaced the cam sensor, crank sensor and map sensor... no change.

Sounds like your jeep runs fine after 30 seconds or so? We may not have the same problem then...
Mine is worse in the cold... stutters while idling, hesitates when engine under load, and sometimes backfires.

Today it was 60° and no symptoms.

07 Rescue Green

yea no back fire and it runs great after a short period of time. It runs rough on startup, doesn't have to be the first one but it has to sit for awhile. Talked to my mechanic today, he's stumped. Time to take it to the dealer but I just know they are going to want to replace a bunch of the stuff I've already replaced.