Codes p0301 p0304

ProjectWhiteTJ · 07-07-2009, 09:39 AM

Hello guys I have searched this topic to death. My jeep will pull these codes when it's cold. Once up to operating temps if I clear the codes they will not come back. The jeep seems to run at full power but every now and then will hiccup and backfire. Also it seems to shake alot at idle although it holds the rpms at ~700. The jeep has new plugs, wires, cap, rotor. Any help would be greatly appreciated.

**jeepmojo01** · 07-07-2009, 09:58 AM

If you google jeep diagnostic trouble codes it will tell you that your computer has detected a misfire in cylinder #1 and cylinder #4

ProjectWhiteTJ · 07-07-2009, 10:08 AM

Sorry I forgot to mention that I know what the codes are, i'm just trying to figure out what's causing it.

**Vigher** · 07-07-2009, 11:38 AM

Quote:

Originally Posted by ProjectWhiteTJ

Sorry I forgot to mention that I know what the codes are, i'm just trying to figure out what's causing it.

I'm gonna take a guess that you used the Double Platinum plugs, if not disregard what I'm about to say.

Remove the Platinum plugs and install standard champion or autolite plugs, your jeep will never be happier!

ProjectWhiteTJ · 07-07-2009, 11:49 AM

Quote:

Originally Posted by Vigher

I'm gonna take a guess that you used the Double Platinum plugs, if not disregard what I'm about to say.

Remove the Platinum plugs and install standard champion or autolite plugs, your jeep will never be happier!

I wish that was the reason. I used standard copper champions

**acrijos** · 07-07-2009, 12:19 PM

Check the spark-plug wires, they might be loose or not making good contact.

ProjectWhiteTJ · 07-07-2009, 12:32 PM

I've checked to make sure they are "clipped" onto the cap and plugs. Next thing I'm gonna do is check the wires out for continuity. Also I swaps the 1 and 4 cylinder plugs with 2 and 3 and it still coming up with p0301 and p0304. The #1 cylinder plug was black. But 4 was clean. I'm so lost!

**Border Dave** · 07-07-2009, 12:50 PM

Did you check the gap of your plugs?

ProjectWhiteTJ · 07-07-2009, 01:03 PM

No I haven't. They are all gapped how I bought them. I doubt it's the gap because when I swapped plugs it should have misfired on 2 and 3 then.

**Border Dave** · 07-07-2009, 01:38 PM

That's good logic, but I would check the gap nonetheless. Oftentimes, they come gapped entirely wrong. Happened to me many times.

How old are your wires? edit: I see that you said they're new. Try switching the wires around and see what happens.

ProjectWhiteTJ · 07-07-2009, 07:50 PM

ya the wire switching and i will check the gap. what is the gap "supposed to be"
thanks for the help for far. with all this rain its tough to get it on the road and drive it.

**Vigher** · 07-07-2009, 09:11 PM

Quote:

Originally Posted by ProjectWhiteTJ

ya the wire switching and i will check the gap. what is the gap "supposed to be"
thanks for the help for far. with all this rain its tough to get it on the road and drive it.

spark plug gap should be 0.035

ProjectWhiteTJ · 07-08-2009, 07:07 AM

Thank you for the info. Hopefully I get some time today to work on it.

ProjectWhiteTJ · 07-09-2009, 08:11 PM

ok guys plugs were all within .002 of each other from .035. swapped the plug wires on 1 and 4 to diffrent plugs and 1 and 4 still missfired. i am completely LOST

jeeptj19992001 · 07-09-2009, 08:20 PM

did you change out your distributor cap and rotor?
did you check the compression of those two?

07-09-2009, 08:20 PM	#15
jeeptj19992001 Registered User Join Date: Oct 2005 Location: Bushkill pa Posts: 1,087 Profile Gallery Classifieds My Jeeps	did you change out your distributor cap and rotor? did you check the compression of those two? __________________ 03 rubi....growing bigger and better every day...