Had a misfire on #4 the other day that finally was bad enough to throw a code. It started as I would get a slight feel like I was going over a rumble strip without the sound. I would give it gas and it would go away. I pulled the COP and replaced the plug. Plug that came out only has 12k on them. Looked very "ashy" and the point on the electrode is gone. A couple of questions:
What is the resistance for the COP?
Would a stuck fuel injector cause these symptoms?

2004 F150 FX4 Screw 212k

PS. I have already done the trans flush for another shaking issue.

 

Coil resistance: https://www.f150online.com/forums/el...-question.html

But heed Jbrew's caution - COPS usually fail under load - static resistance may read fine and you still have a bad COP.

Stuck injector - plug would not be firing and it would likely be wet. And if it persists and is bad enough, hydrolocking and cat damage ( there is a link to a thread on it in the link below )

Check them like this: https://www.f150online.com/forums/ar...-new-post.html

Buy a spare COP ( Visteon or Motorcrat to test with in #4, or swap with another cylinder to see if misfire follows.

Was the plug loose? Plug brand & part #? Pic?

 

Plug seemed to come out fairly easy, it might have been loose. Motorcraft SP-515. It was not wet. I might have a combination of problems. I will pick up a new COP tomorrow and install. Is there a way to test the injectors? I have a set of injector lights that plug into the connection to make sure they are getting power, but what about the injectors themselves? If I have an injector that is not working 100%, would it cause the same symptoms?

 

Mornin';

Other than the simple 'drip' leak bench test as described in that PDF, dynamic injector testing/cleaning needs to be done by a shop with experience and equipment. Not sure if there is an end-user in-circuit testing equivalent to spark 'noid' lights for injectors.

On Rare occasions the drivers in the PCM can go bad - or harness/connector issues occur - those are more common.

BTW - plugs need to be @ 25 ft-lbs, dry.

As for symptoms - I'd say yes.

May be prudent to get a Ford shop to run full IDS diags on fuel system/ignition system components, signals and operation. You don't want to go by SWAG here - too much risk to the motor and downstream components.

If fuel leakage turns out to be the culprit - or even of it's erratic spark, remember to change your oil to remove dilution when it's fixed.

Good luck.

MGD