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2004 F250 V10 misfiring


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My 2004 F250 with a V10 has begun misfiring on a couple of cylinders.  I replaced a couple of coils with the “economy grade” from NAPA to no avail.  I then replaced those with OEM quality ignition coils that cured one cylinder, but not the other.  Additionally I lost another cylinder.  Has anyone else had any experience with this that could point me in the right direction?

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Yes.  First it showed 9 & 10 misfiring so I replaced those coils with the cheap, in stock coils.  After driving it still showed 9 & 10 misfiring.   So I replaced them with Denso OEM grade coils.  9 cleared up, but 8 & 10 now misfire.

Roughly a month ago I replaced the coil in 10 along with a spark plug and a thread repair kit because it ejected spark plug 10.

I had gone through a rash of coils 5 years ago, but not recently.

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The multiple misses and the miss moving to different cyls makes me think the ground signal that excite the coils coming from the ecm may be intermittent.

Pull the big connector off the ecm and look for corrosion.

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1 minute ago, MTO said:

The multiple misses and the miss moving to different cyls makes me think the ground signal that excite the coils coming from the ecm may be intermittent.

Pull the big connector off the ecm and look for corrosion.

Will do.  Thank you Mark!

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35 minutes ago, 1586 Jeff said:

Is there such a thing as a coil tester?  Something like a noid light that is used for testing injector pulses?

Wait a ford shot a spark plug out the head? No way.... 

Jk I had a work truck that shot them out on a weekly basis. Sometimes I'd drive it that way a day anyway. Hated that engine but it kept on keeping on 

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1 hour ago, MTO said:

How did you determine the missing cylinders? Scan tool?

 

1 hour ago, 1586 Jeff said:

Yes.  First it showed 9 & 10 misfiring so I replaced those coils with the cheap, in stock coils.  After driving it still showed 9 & 10 misfiring.   So I replaced them with Denso OEM grade coils.  9 cleared up, but 8 & 10 now misfire.

Roughly a month ago I replaced the coil in 10 along with a spark plug and a thread repair kit because it ejected spark plug 10.

I had gone through a rash of coils 5 years ago, but not recently.

Not sure what scanner you are using and it shouldn’t matter but I go into the mode 6 section and there is a PID for engine misfire.  It’s like 54 maybe? It shows the total misfire for each cylinder.  This has worked for me.  The cylinder contribution test on the snap on scanner has never helped me much.  

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Worked on a buddies 5.4 that showed misfire, we swapped coils around with no change. Pulled fuel injectors out and just blew them out with compressed air, put them back and has been running great for 5k now and counting

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Swap coil from missing cylinders to non missing cylinders ie coil 10 to cyl5 and move plug 10 to cyl4. Drive and see if misfire follows a component. If not suspect an injector on the misfiring cylinder, wiring or compression related cause. Ford's can also be a pain. Sometimes they attribute a miss to the wrong cylinder. If firing order is 1-3-4-2 and the misfire code is for 3, on ford's sometimes the true miss is on 1 or 4 and the ecm assigns it to an neighboring cylinder in the firing order. So remember this when moving components and move them to non neighboring (in the firing order) cylinders. 

An oscilloscope can be used to monitor the the ecm driver to see if it is burnt up or functioning properly. But the same can be achieved by using a spark tester and a known good coil plugged into the coil connector in question. Also don't rule out a possible miss from a vacuum leak. Cylinders 8 9 and 10 are all on the same bank and next to each other. You could have a leaking intake gasket in that area. How are the fuel trims on that bank. I have seen leaks that aren't bad enough to trigger a light cause issues on one cylinder before. 

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40 minutes ago, 885 said:

Swap coil from missing cylinders to non missing cylinders ie coil 10 to cyl5 and move plug 10 to cyl4. Drive and see if misfire follows a component. If not suspect an injector on the misfiring cylinder, wiring or compression related cause. Ford's can also be a pain. Sometimes they attribute a miss to the wrong cylinder. If firing order is 1-3-4-2 and the misfire code is for 3, on ford's sometimes the true miss is on 1 or 4 and the ecm assigns it to an neighboring cylinder in the firing order. So remember this when moving components and move them to non neighboring (in the firing order) cylinders. 

An oscilloscope can be used to monitor the the ecm driver to see if it is burnt up or functioning properly. But the same can be achieved by using a spark tester and a known good coil plugged into the coil connector in question. Also don't rule out a possible miss from a vacuum leak. Cylinders 8 9 and 10 are all on the same bank and next to each other. You could have a leaking intake gasket in that area. How are the fuel trims on that bank. I have seen leaks that aren't bad enough to trigger a light cause issues on one cylinder before. 

Hmmmm.  That gives me something else to look at.

And I have been fishing in the dark by forgetting that the cylinders run 1-5 on the right bank and 6-10 on the left (driver’s) side bank.

 Thank you!

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i have replaced coils in my 5.4s and sometimes they are bad out of the box napas ebays and oem. had them quit after a couple hours.  its maddening. sh*tty import crap

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Just now, edwardporter1 said:

i have replaced coils in my 5.4s and sometimes they are bad out of the box napas ebays and oem. had them quit after a couple hours.  its maddening. sh*tty import crap

No kidding!!!!

 I have been swapping coils around in an attempt to prove out coils and I now have numerous coils labeled in various manners.  I want to wash my hands of this truck for so many reasons, but I cannot afford to do so.

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On 10/1/2020 at 9:43 PM, 1586 Jeff said:

No kidding!!!!

 I have been swapping coils around in an attempt to prove out coils and I now have numerous coils labeled in various manners.  I want to wash my hands of this truck for so many reasons, but I cannot afford to do so.

Did you cure it?

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Take the radiator cap off, drive 6.8 ferd out and pull 6.0 Chevy in.  Reinstall radiator cap.

 

If you insist on fixing then use genuine Motorcraft coils, boots and plugs.  Denso is good but that's for GM, not ford.  One thing I've learned over the years is some parts are very sensitive to certain manufacturers.  Not saying generic parts house parts don't work.  Lots of people get by.  I've had too many comebacks over the years with certain brands of parts so certain problems get specific brand parts.  Coils on fords are one of those.

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On 10/1/2020 at 11:28 AM, Missouri Mule said:

Wait a ford shot a spark plug out the head? No way.... 

Jk I had a work truck that shot them out on a weekly basis. Sometimes I'd drive it that way a day anyway. Hated that engine but it kept on keeping on 

Weekly? Jeez. Had my '05 mountaineer eject a plug. Used the calvan kit to rethread new in and its still holding strong 3 years later. 

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