On my 04 fx4 screw cab 5.4L with 75,000 miles on it, When traveling down the road, after the truck already goes into overdrive, I can press the accelerator slightly (not enough to make it jump out of overdrive) and It has a slight skip...Its not constant, itll just skip a few times...Itll only do it at a low RPM also.. Once the RPM's go up it will quit..I havent washed the engine lately so I know that nothing is wet under there..Could it be something in the tranny or in the engine..What could the problem be????

 

There is one faulty coil.
Not a total failure but faulty.
Stress test is in order to find which one it is.

 

I was just coming on here to post the exact same thing...and your post was on the top of the list...go figure.


I have the exact same problem. I replaced all of my cops with globals four weeks ago (put new plugs in too). So I guess one of my globals is faulty? I knew $69 was too good to be true...shame on me for listening to you guys here, lol.

So the question is, how do I perform this stress test? I have no codes, been running like this for about three weeks and still no codes.


kev

 

Here it is the background again for those who don't find it by searching.
The reason no code and CEL lamp will appear is the fault in not in long enough to satisfy the diagnostic program and set a logic fault.
The varying conditions that bring on the fault come and go as you drive and the load changes.
During cruise in OD and light loads, and low throttle conditions, the fuel is cut back, the EGR operates and ignition timing is advanced.
This results in very lean conditions of nearly 20 to 1 in air/fuel ratios.
It take more voltage from the coils and good plug condition to reliably fire these lean mixtures.
This set of condition is generated by design to effect two end results. One is reduction in emmissions of NOX, second it to enhance fuel mileage possable with leaner mixtures.
These conditions result in increased demand on the ignition system as discribed above.
If one coil has shorted turns it's voltage output will be to low or marginal for that cyclinder such that a missfire occurrs only during the time these conditions are present.
As soon as extra engine load is called, the mixture conditions richen up to the point the faulty coil will now be able to fire that cylinder and the miss goes away.
As this happens the fault count for logic failure is cleared out of memory buffer that would set a code and light the CEL lamp. Then it starts all over again the next time the conditions are entered.
This being considered an intermittant type of issue, the diagnostic program cannot determine what cylinder (the record keeps getting cleared) it is unless a deeper look is taken with a 'diagnostic' scanner (not a reader) by one who knows what to look at, then there is possably of no varifiable record if the issue has not been stored in that location of which there are 8, one for each cylinder.
The only other way to detect the faulty coil is with an output test called a stress test.
You cannot perform this test as a dyi under normal conditions. A resistance test will not find shorted turns unless there is an absolute short /or open then the cylinder will miss permantly and set a code and lamp that can be seen.
Coil fault occurs mainly because the wire is only enamel covered. If during heating/cooling cycles over time there is a rub-though failure due to the turns laying upon each other , a short between 'two turns' occurs. This alters the total magnetic field intensity in the downward direction and lowers the output voltage, as a result.
Lastly, mass replacement has the hazzard of one new coil being faulty such that you are back to the same condition again unless that coil is an outright failure or failure occurrs again at some later time. This can be the results of mass production parts for which you have to accept.

The average owner is not usually knowledgable in enough depth about these systems and often a dealer tech is not and/ or not allowed to go to these levels in troubleshooting, so places parts with a short road test to get the vehichle out the door only to result in recall and confusion.
Thought these systems should make it easy? It won't get better anytime soon.
Better hope your doctor dosent just replace parts when your ill without knowing what he's doing.
Reread this reply several times to get the understanding of what goes on with this type of miss and the 'total' of it's cause and where you have to be, in order to solve it.
I have been here and done this with all experiences.

 

So how do I need to go about fixing it?? Buy a coil and replace each coil with the good one, one at a time to see which one is bad??

 

Bluegrass,

Thanks you for the detailed reply! Is there a FAQ section on these boards? Can a moderator make your reply a 'sticky'? It just seems like everyone I know who owns a modular ford v8 has had trouble with COPS (I live in western PA, humid and wet all of the time). Yet nobody has been able to describe the reasoning behind it like you did!

Thanks,
kev


BTW; Albritton,

After re-reading his reply about 8 times, I believe that is the easiest option even though it is time consuming. I'm still not sold it not being a cop brand issue though. I'm kicking myself for not purchasing the Motorcrafts or MSD's.

 

MY truck is going back in for this exact same issue. I went in a month or so ago and the service manager told me the miss was a transmission issue and I should do a flush. ~$180 later, problem still exists. I took it RIGHT back to the dealer and told them the problem still exists so a tech comes out with a laptop and we go for a ride. He asks me to make the miss happen and when it does, he turns the laptop towards me and says, "Here's your problem. Watch #1 when the miss happens." I watch the screen as the #1 cylinder value drops off the screen as the miss occurs. He said it's a bad COP and I should do the plug for that cylinder as well. As we get back to the dealer, he told me to ask for him every time I come in and don't trust the counter guys since they don't actually WORK on these trucks.

We are scheduling a time for the work to be done and calls are being made to my warranty company. The warranty will cover the COP, but not the plug change costs.

Just my experience, take it as you wish.

 

Jim, you proved the point very nicely.
None of these issues are impossable to find if the tech is willing/allowed/ and able to do the investigation correctly.
It also demenstrates that any issue that is more than 'very evident' cannot be serviced by the owner except for some kind of luck throwing parts at it that most always ends up costing more than if a proper technical fix were done at the beginning.
The service writers cost the customer more money than is gererally realized by their guessing and excuses that snow's the customer and takes advantage, due to there lack of knowledge.
Very nice end result you got.
.
Now if we can only take back our country from the pending socialism that none of you will ever like when is finally hits home.
Bottom line is get educated as to what is happening and reject it.
It's like a live Lobster in cold water on the stove; it does not know what is happening until it's to late.
Good luck.

 

I sent the truck to the shop today to get the spark plugs and told them to find the bad coil and replace that too..I hope that fixes the problem..Those spark plugs are $10.00 each..WOW!!!

 

He replaced the #1 coil and all the spark plugs ad so far so good..the skip is gone..The plugs were actually a little over $13.00 each!!! Thats crazy...I hope they at least give me a little better gas milage

 

I took mine in for a laundry list of work to be done:

COP and plug on cylinder 1 changed, injector flow tested and replaced if needed
4x4 hubs and/or vacuum module
new pass exhaust manifold...2 studs snapped and warped the mani
headliner rattle

The service manager called today and let me know it will be ready Fri.

Can't wait...if it comes back all fixed, PHP will be getting my Edge for a Gryphon upgrade.

 

My skip in OD was the fuel filter.

 

I changed mine 100 miles ago...I was hoping it was something as simple as that and could be fixed in 10 minutes for $15, but not so lucky.

 

My extended warranty company covered everything except the exhaust manifold leak, it was determined as a pre-existing condition since the warranty was purchased separately after my factory warranty expired.

I forgot about getting the pass lower ball joint replaced as well. Tab came to over 8 bills and all I paid was my $100 deductible. I even got a free rental truck while mine was in the shop.

The truck runs great...absolutely no hesitation when slight throttle applied in OD, just goes down smooth into the right gear and pulls as it should. My MPG seems to be a bit better...I averaged 15.9 for about 100 miles of city driving. I'll just have to finally have the problem resolved.