Some of you know that I had some extensive experience with COP coils and plugs over nearly a year's time, with a lot of accumulated findings.
The issue was light throttle missing/stumbling.
I went thru 4 sets of plugs of three different makes and found the plug issue that is suposed to be present for these motors and the exclusive use of Motorcraft plugs is a myth. They all did there job.
Finally replaced all coils and still had the remenants of the miss.
It wasn't until I had to have dealer service on suspension and exhaust header bolt warrenty that I had them stress test the ignition.
It was found that two of the 8 new coils were failures.
I replaced those two with two originals and the miss is gone.
As it turns out, not all the original coils were faulty.
I now have a good full set of after markets in place and have not had my issue return.
You can have any coil old of new fail and the only way to solve for the fault is either some luck at changing them or have them all stress tested to find the absolute one/s in fault.
As for spark plugs, I have found absolutly no issues using Motorcraft, Autolite or Bosch (single) plat types, for reliability.
Installed properly, they have no issues that I have been able to see.
Lastly, my missing issue and how it showed never sets a code or brings on a CEL lamp due to the nature of the problem.
The nature of the problem was that the plugs could not fire a very 'lean' mixture under the peticular driving conditions due to one or more coils that apparently had some shorted turns in their windings that did not render the coil in a dead state or degraded enough not to fire the plugs under richer conditions. This stems from the fact that a lean mix in the plug gap is very hard to fire because the 'dielectric' constant is high as opposed to a richer mix that is lower. The combination of the two conditions the weak coils and the lean mix become ' a marginal' condition for ignition reliability, therfore set no code because there is not enough short term history stored before is goes away clearing the history to only start over again for the next time it happens.
With this special condition present, once in awhile the truck would act as if you turned the igntion off and back on then run again. My theroy is that the bad coils propagated interference back to the PCM to the point it upset program processing momentarily causing program signal interference, then any results are likely until the program recovers.
This is how it all fell out for my trials and testing. Truck runs really good now for well near 10,000 miles with the BOSCH plugs in place (not the 2 or 4 ground type).
Not that I have a preference for plugs in this motor but the BOSCH were the easier to fire under the original trouble conditions so left them in until it's time to put new ones in.
Additionaly I found that new plugs, under the fault condition, would clear the miss for roughly 500 to 2000 miles before the miss came back because they simply were easy to fire in a new condition but that the BOSCH held the longest time before the miss returned with their fine wire tips.
Bottom line is the coils have to be good or nothing else works.
Bewhere of the tendency to condem a part on the basis of circumstancial evidence rather than proof. It often comes back to bite again, if you do.
Long reply post but I think there is something important here to offer on a number of points.

 

amen!
i have wasted olot of money learning these things about all the brands.
i decided to catch up on eec : the sysytms that i own. because i kept getting raped by mechanics.
It seem to be all about the vaccum,

Tumba god of f150 vacuum

 

Thanks for the in depth post.

Don't want to hijack the thread, but I think this question fits here. If I wanted to have my cops "stress tested". What do I ask for? Who can do this? What does it cost if I bring the COPs in a bag and not installed in the truck?

Thanks.

 

To keep it short -

I tested as well with far different results . I used the same coils and tested 3name brands of plugs.

Bosch - Truck fired once - that was it. NO START

Autolite - P303 ,P305 and a multiple misfire code..All within 40 miles time.

Motorcraft - No Problems.

That's was with a 98 5.4L motor and my personal experience.

Testing low grade misfires is possible for the DIY - easier at the dealer. But it's possible. I posted all the info, how to's so much if you search your bound to stumble across them..

 

its no hijack. that is what this post is about. after reading you post i wanted to learn to diagnos that myself. My 97 has 167,000 on it and has the original coil packs.
When i quit mech work HEI was the big deal. i'm trying to learn eec now

by the way i've got a dwell meter if you need to use one! lol

 

i don't know about stress testing coils. these other guys know more about that

 

Stress test is done at the dealership.

Theres a Mode 6 test that looks into cylinder history as well - they might be one in the same.

Mode 6 - Channel 3 , I think is stress.. Not sure , but it something like that.

Bluegrass will know - I'm not a tech, just work on my own stuff. I test during the drive cycle and monitor that way.

 

i have the same prob with the autolite plugs within 40 or so miles

 

has anyone else ever seen a message like that on their obdii code scanner "large leak" i didnt know they were capable of something like that

 

Seems like I read somewhere there is a code for "large leak". I think it had to do with vacuum testing the fuel tank. The "large leak" code went along with missing gas cap.

 

when i saw this code i found the pcv line off the back of the intake i didn't listen to it run before i checked codes.
, it may ahve been the tank, but i hooked that line up and sent him on his way. i was just surprized to see that message thanks for the reply.
i'm kinda new at eec but learning fast
thanks

 

Make's me wonder if setting the sparkplugs gap to .035 would help too

 

[QUOTE=jbrew]Ford swapped the COP boots in 99 . That was mistake - don't know the reasoning behind it . I use my 98 boots on a set 2000 Factory COPs - (the Yellow labled COP's). The older style boots are twice the thickness in material , the insides are solid brass and copper with a shorter stainless spring.
/[QUOTE] <<<< i tried to cut this quote 3 times
give an e for effort

guess thats why i haven't had any problems with that


thanks
i re read allot to guys!