please help p0304 and p0316 only after 1st time start in the morning

[Jack50]

Can someone please give me some advise.
Me and my mechanic are lost on this 1
If my 06 Explorer 4.6 L sits more then 8 hrs when I start it. I get codes P0304 + P0316 pending.
I have changed plug, coil, injector, fuel filter, checked for vacuum leaks, cleaned MAF and throttle body and all nothing seems to work.
The plug looked clean and exactly like the other ones I check in other cylinders.
Which were all changed 3 months ago.
After the 1st start up in the morning, I clear the codes and don't come back till the next day after it has been sitting 8 plus hrs.
I even got it to pass emission tests after I cleared the codes and drove it around for 1/2 hr.
I idles smooth with no shaking at all.
Please any suggestions
Thank you

 

[Explorer_PL]

Did you replace just #4 coil or all of them ?
Did you use Motorcraft or aftermarket coils ?
#4 is under the windshield and #4 and 8 are prone to collect rain water (or carwash) in the wells causing misfire.
Can you swap the 4 coil to another cylinder and see if the code moves to some other 30x ?

 

[Flag Gibby]

So what you are saying is that on a very cold engine you get a code for a misfire on cylinder 4 only on startup? Or does it still misfire while it is running. Put a code reader on it while it is running and monitor it to see if cylinder 4 continues to misfire. If that is the case then I would say to check the switching signal wires running to that COP to make sure that there is nothing wrong with them that causes a bad connection when cold (maybe condensation inside the connector?).
This link may help you and your mechanic out: http://troubleshootmyvehicle.com/ford/4.6L-5.4L/coil-on-plug-misfire-tests-1

 

[Explorer_PL]

https://www.youtube.com/watch?v=RD4lgno-_as

 

[Jack50]

Thank you for all the replies.
I have switched coils to make sure it isn't that even though the plugs aren't old. I switched them also just in case there was a bad plug and the code still is the same.
The coils are motor craft.
As far as monitoring the code have done that also. As mentioned it only comes on after siting 8+ hrs.
Had a friend of mine who does custom work on trucks look at it last night while it was running and he said it sounds great.
But for some odd reason those codes show up every time it sits 8+ hrs

 

[Explorer_PL]

Oil getting thick ...
Valve issue ????
Can you test compression on # 4 ?

 

[Jack50]

oil was just changed recently use 5w 20
will have go do compression

 

[Flag Gibby]

I personally think that it has to do with the switching signal wires going to that COP. Cold wires = faulty contact
Have you verified the signal on a cold startup?

 

[Jack50]

haven't tried that yet

 

[Jack50]

Update. Codes seem to have gone away. Sprayed coil and injector connections with quick dry cleaner. Put chevron injector cleaner in tank. Next couple,days have been code free.
Thamk you everyone.
Good chance there was a dirty connector