Cylinder 5 misfire P0305
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JK Enthusiast
Joined: May 2010
Posts: 497
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From: Hampton, VA
Cylinder 5 misfire P0305
So here's the background...I overheated my motor very bad during last summer. I started burning oil badly. I got a bad misfire the other day and it won't stop. Replaced the plugs not too long ago. I just replaced cylinder 5 plug again and sea foamed the motor today and didn't get any better. Here's a picture of the plug I pulled and any help is appreciated.
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JK Junkie
Joined: Feb 2011
Posts: 2,318
Likes: 12
From: New Hampshire
might want to explain if the plug is before or after the sea foam it looks wet to me
if that's before the sea foam its running rich to much fuel maybe a fuel injector but if after sea foam then its not a accurate way of telling anything and sea foam isn't recommended realy to start with a throttle body cleaning is a easy step as you prob already did though???? sounds to me a compression test should be done to rule out worn rings
just my guess but im no
expert either
just my guess but im no
expert either
Last edited by jeepmojo; Jan 26, 2014 at 03:59 PM.
JK Junkie
Joined: Feb 2011
Posts: 2,318
Likes: 12
From: New Hampshire
shouldnt be wet it should be tan
and dry ! you got to much fuel getting there i dont know why though others might have a better guess mine is have the compression check or at least fuel injector
Thread Starter
JK Enthusiast
Joined: May 2010
Posts: 497
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From: Hampton, VA
No. Changed the plug and switxhed a couple wires to see if the miss would move, but it stayed on cylinder 5. I bought a leak down tester to try this weekend.
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JK Enthusiast
Joined: Mar 2009
Posts: 213
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From: Northwestern Ontario
I just had the same thing two weeks ago with my #4 cyl, I replaced the plug, wires and coilpack and no more error code, I have just over 130,000 kms on my 3.8L and was running the factory coilpack and wires up til now
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JK Newbie
Joined: Sep 2007
Posts: 32
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From: Piscataway, NJ
Something to look at:
There is a known issue with some of the injector wiring harnesses on the 3.8.
I happen to have that issue. Just 2 months after I bought my JK (08) I got the electronic throttle control warning light and got an unresponsive accelerator pedal.
I called the dealer, they picked up the jeep and had it diagnosed and fixed in less than 3 hours.
Turns out my #5 injector on the harness was momentarily shorting out and confusing the computer. The computer in turn thought it was the throttle position sensor. (It was not)
They repaired it and it was fine until last year when they pulled the manifold off and disturbed the repair. Now the issue plagues me again intermittently. It's going back in sometime in the next 2 weeks to be addressed again. Possibly something for you to check.
There is a known issue with some of the injector wiring harnesses on the 3.8.
I happen to have that issue. Just 2 months after I bought my JK (08) I got the electronic throttle control warning light and got an unresponsive accelerator pedal.
I called the dealer, they picked up the jeep and had it diagnosed and fixed in less than 3 hours.
Turns out my #5 injector on the harness was momentarily shorting out and confusing the computer. The computer in turn thought it was the throttle position sensor. (It was not)
They repaired it and it was fine until last year when they pulled the manifold off and disturbed the repair. Now the issue plagues me again intermittently. It's going back in sometime in the next 2 weeks to be addressed again. Possibly something for you to check.