Changed Cop,plug, still missing??
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New User
Joined: Mar 2005
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From: Oceanside CA
Changed Cop,plug, still missing??
Hey guys,
I have a 2000 F250 with about 110k on it. I recently changed all of the COPs because I had a couple start to miss. New boots and I also changed the plugs about 20k ago. So last week it starts missin real bad and throws a code p0303. So I replace the COP on #3 cylinder and it fixes the problem. Yesterday, same thing happens and it is the same code, p0303. So I swap the plug and COP with Cylinder #1 and I am still getting a p0303 after I cleared it. I have checked for any vacuum leaks and cleaned the MAF and replaced the fuel filter. What else could it be???
Thanks guys
I have a 2000 F250 with about 110k on it. I recently changed all of the COPs because I had a couple start to miss. New boots and I also changed the plugs about 20k ago. So last week it starts missin real bad and throws a code p0303. So I replace the COP on #3 cylinder and it fixes the problem. Yesterday, same thing happens and it is the same code, p0303. So I swap the plug and COP with Cylinder #1 and I am still getting a p0303 after I cleared it. I have checked for any vacuum leaks and cleaned the MAF and replaced the fuel filter. What else could it be???
Thanks guys
Posting Guru
Joined: Apr 2006
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And its happening on different cylinders? At different times?
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New User
Joined: Mar 2005
Posts: 6
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From: Oceanside CA
No, it only happens on cylinder #3. I swapped the plug and COP from Cylinder#3 with the plug and COP that were on cylinder #1 which are fine to see if it would fix it. I was thinking that if it was a bad COP it would throw a new code for cylinder #! since I moved it there. But threw the same code on cylinder 3. So I think the COP and plug are fine. Does anybody know what else would make it throw a missfire on #3 code (p0303)??
Thanks for replying saskdiesel
Thanks for replying saskdiesel
Posting Guru
Joined: Apr 2006
Posts: 2,216
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No, it only happens on cylinder #3. I swapped the plug and COP from Cylinder#3 with the plug and COP that were on cylinder #1 which are fine to see if it would fix it. I was thinking that if it was a bad COP it would throw a new code for cylinder #! since I moved it there. But threw the same code on cylinder 3. So I think the COP and plug are fine. Does anybody know what else would make it throw a missfire on #3 code (p0303)??
Thanks for replying saskdiesel
Thanks for replying saskdiesel
We had a 5.4 do the same thing and ended up spending over $100 for the dealer to diagnose check the wiring to the cylinder. As soon as the tech moved the plug to the cop the misfire stopped.
We went back to the campground and cleaned up the connection and it eliminated the misfire.
I would replace that plug before I did anything else. Plugs can crack anytime.
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New User
Joined: Mar 2005
Posts: 6
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From: Oceanside CA
Good idea.
I'll check the wiring and clean it up tonight.
I'll let you know if it fixes it.
Thanks again
Matt
I'll check the wiring and clean it up tonight.
I'll let you know if it fixes it.
Thanks again
Matt
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