Replaced Plugs and COP, now voltage spikes?

[CharlesUSMC]

So a few weeks ago I got P0305 on my '05 Limited Edition 5.4L V8 Expedition.

As this is an upgrade from my 1st Gen 2001 5.4L V8 Expedition, i went ahead and changed the spark plugs 1st since they were long over due.

This made my truck run much much better. But then started getting misfires from P0302.

went ahead and picked up a BWD COP and replaced the COP on cylinder 2 (2nd from the front, passenger side)

I noticed the plastic clip had lost it's tab and it didn't actually 'click' when pushing the wiring harness plug onto the COP. So i used a little electrical tape to ensure it doesnt slip off while driving. It's been holding well and there is no wiggle and the COP connector does not come loose after driving.

So I replaced the COP, granted it could have been just the clip being loose before applying the tape.

Today on my way to work the Check Charging System light came on and my output voltage jumped from ~14 to ~16 volts. It went away, came back a second time, and has gone away since. Scanner didn't throwing any error codes, pending or stored.

Also noticed that this vehicle will shudder when gassing through a turn after being stopped if the engine is misfiring. Initially i thought it was something related to suspension or 4wd... but it got worse when i started getting the p0305 misfires initially. replacing the spark plugs helped stop it occasionally... but then the loose plug, replaced COP, and voltage regulation issues...all have me totally stumped on what the real problem is.


also put some Seafoam through the gas tank. As the system has never been cleaned since i've owned it. (about 30k miles). This helped my old 1st gen expedition's rough idle a lot after i swapped out COPs and plugs, so i thought i would try it again.

I'm thinking i just need to get 8 Motorcraft COPs, replace them all, and figure out how to replace the plastic clip that plugs into the COP on cyl 2.... then go from there if i keep getting issues.


Thoughts?

ps. used motorcraft spark plugs. replaced alternator w/ OEM original about 2 months ago when voltage was low around 10v and battery was dying.

 

[Stanger4Life]

So a few weeks ago I got P0305 on my '05 Limited Edition 5.4L V8 Expedition.

As this is an upgrade from my 1st Gen 2001 5.4L V8 Expedition, i went ahead and changed the spark plugs 1st since they were long over due.

This made my truck run much much better. But then started getting misfires from P0302.

went ahead and picked up a BWD COP and replaced the COP on cylinder 2 (2nd from the front, passenger side)

I noticed the plastic clip had lost it's tab and it didn't actually 'click' when pushing the wiring harness plug onto the COP. So i used a little electrical tape to ensure it doesnt slip off while driving. It's been holding well and there is no wiggle and the COP connector does not come loose after driving.

So I replaced the COP, granted it could have been just the clip being loose before applying the tape.

Today on my way to work the Check Charging System light came on and my output voltage jumped from ~14 to ~16 volts. It went away, came back a second time, and has gone away since. Scanner didn't throwing any error codes, pending or stored.

Also noticed that this vehicle will shudder when gassing through a turn after being stopped if the engine is misfiring. Initially i thought it was something related to suspension or 4wd... but it got worse when i started getting the p0305 misfires initially. replacing the spark plugs helped stop it occasionally... but then the loose plug, replaced COP, and voltage regulation issues...all have me totally stumped on what the real problem is.


also put some Seafoam through the gas tank. As the system has never been cleaned since i've owned it. (about 30k miles). This helped my old 1st gen expedition's rough idle a lot after i swapped out COPs and plugs, so i thought i would try it again.

I'm thinking i just need to get 8 Motorcraft COPs, replace them all, and figure out how to replace the plastic clip that plugs into the COP on cyl 2.... then go from there if i keep getting issues.


Thoughts?

ps. used motorcraft spark plugs. replaced alternator w/ OEM original about 2 months ago when voltage was low around 10v and battery was dying.

I don't really think this is it, but I would have your alternator and battery tested eventhough you replaced it. That and make sure your accessory belt has good tension on it. I would also go over everything you touched, make sure you plugs are on snug and haven't backed out by chance, and that they are gapped properly. The best thing you can do is start eliminating possibilities, so you can focus on a smaller amount.

 

[stamp11127]

If your reading the voltage from the cluster there is a chance that the reading is false. But if you are using another voltmeter or dmm to verify the 16 volt reading, there is only one item that can cause that. The voltage regulator is on the way out.
All of the interior lights would be brighter than normal when the vr acts up with over voltage. If that isn't happening I would suspect a faulty gauge or electronics in the cluster.

There are a few ways to handle the connector, the best way is to replace it. Or you can use rtv silicone to hold it in place. Make sure you don't get any on the contacts.