I have a 2002 F250 5.4 L with an intermittent Misfire. A little history on the truck in 2011 I replaced the motor with a Ford long block motor, only the block, I used my electronics, intake, etc, this was brand new from Ford. The truck has a total of over 300K miles. Recently it has developed an intermittent misfire. I have changed all the coils and plugs and the misfire is still present. The codes are showing a misfire in cylinder 3 but could be 4 too. The misfire is intermittent because this morning I changed the plugs and truck ran fine, drove to store and it started missing, turned truck off and started up and ran fine again. It has been doing this off and on for a few weeks.

Any ideas??????

 

Given what you have done and that it is intermittent, my first guess would be an injector is sticking, but I hate to guess. Have you pulled the codes?

 

The code was P0354

 

I bet its still a coil. Either you have a spring in the coil not making with the plug or a weak spring that has been compressed and is kinda short. Pull on the springs to lengthen them back out. ( I solved my problem like this)
Pull the coils on those cylinders and check the springs in the coil.
Make sure they are in good shape, no cracks.

 

P0354 Ignition Coil "D" Primary/Secondary Circuit

There is a possibility of #4 coil is acting up . Sometimes it runs fine when it is cold and starts internally arcing when it gets hot .

Suggestion: Swap #4 coil with #3 and see if the error code moves from P0354 to PO353 . If the error codes moves, then it is an acting COP coil that needs to be replaced .

I suggest either Motocraft COP or (its maker) Standard as a replacement .

Good luck,

 

Update: Took the truck last night be hooked up to actual diagnostic computer. Cylinder 3 is the problem, pinpointed to possible fuel injector, change the injector for cylinder 3 and problem still exists.

Pulled out spark plug in cylinder 3 and the tip is gone....

Any ideas????

 

How much of the tip? If the electrode is burned up that's not the end of the world. If the little bent piece that stets the gap (name slips my mind) Id be worried it's in the motor.

 

The 5.4L plugs don't have a "little bent piece that stets the gap". They look like this:



A missing electrode tip would indicate a very high combustion chamber temperature. That would point to a lean condition, which would be very possibly caused by a bad injector.

The tip burned off while the injector was bad, so even after you replaced the injector you still have a miss. I think if you replace the spark plug you'll be OK now.

 

Redford- what years are those plugs for? I just bought plugs for my 99 5.4, and they don't look like that. They are Motorcraft SP-479 and DO have the "little bent piece that stets the gap".

 

3V engine, I guess.

 

Yup, that is a 3V plug.

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