Code P0307

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Sep 16, 2009 | 04:20 PM

happeetxn

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Code P0307

Howdy all,
My wife's CEL (Her vehicle, 2003 5.4L, 4x4, EB Expy) came on and long story short I got a code P0307 -Cylinder 7 misfire.

So my question is which cylinder is #7 and is there any way to determine what is bad, i.e COP, wire, plug, or injector?

I read the write up for the COP replacement and will print this off prior to making the repair.

Thanks for the help.

Craig

Sep 16, 2009 | 09:48 PM

alloro

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From: 0,0,1

Quote:

Originally Posted by happeetxn

So my question is which cylinder is #7 and is there any way to determine what is bad, i.e COP, wire, plug, or injector?

Swapping the COP, plug, or injector to different cylinders and seeing which cylinder the misfire moves to, is really the only sure way to know which component is the problem.

Cylinder layout:
Back of engine
|-4--8-|
|-3--7-|
|-2--6-|
|-1--5-|
Front of engine

Sep 17, 2009 | 01:30 AM

happeetxn

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Thanks for the reply.

Craig

Sep 19, 2009 | 12:47 PM

happeetxn

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Quote:

Originally Posted by alloro

It appears that it was the COP. Replaced it and everything seems back to normal. The job wasn't near as bad as I thought it might be. Thanks to the member who did the write up on the COP replacement.

A concerning find was that the boot on the COP and the exterior of the plug had a lot of rust on them. I took pics and will post them later.

Now a follow up question. Do you wait for these to go out or do you just start replacing them? The plugs need to be changed out around by now if the original owner didn't do it right? The truck now has 110,000 miles on it, and maintenance has been done regularly to the best of my knowledge.

Craig

Sep 19, 2009 | 12:57 PM

happeetxn

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duplicate post.....

Craig

Sep 19, 2009 | 07:30 PM

alloro

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Quote:

Originally Posted by happeetxn

A concerning find was that the boot on the COP and the exterior of the plug had a lot of rust on them. I took pics and will post them later.

Now a follow up question. Do you wait for these to go out or do you just start replacing them? The plugs need to be changed out around by now if the original owner didn't do it right? The truck now has 110,000 miles on it, and maintenance has been done regularly to the best of my knowledge.

The rust on the plug and boot was because water got down into the plug hole. This usually is a sign that the boots are old and need replacing.

When I had a COP go out I replaced at 8 at the same time and kept a few of the old ones as spares. The plugs are supposed to be changed at 100K miles, so you're due for a set.