4.6L V8
5 Speed Manual
4x4
74000 mi

 

May I ask what the solution to your problem ended up being? I am experiencing something similar, and would REALLY appreciate your help.

Thanks!

 

Soon after I posted the problem got much better. It was still there, but barely noticeable. As the weather got warmer the hesitation had almost disappeared. Recently I brought the truck to my mechanic for some minor brake work. When I picked it up he told me I had a couple of coils that were pretty bad. He had noticed the hesitation when he drove it before and after the brake work. I explained what had happened with the hesitating during the winter. He had hooked the truck up to the diagnostic computer and he had a code indicating the coils were misfiring. He troubleshot it to 3 coils. He is confident that is what the issue is. I am having the bad coils replaced in a few weeks. Hope this helps.

 

May I ask if the check engine light ever came on? My problem really sounds like bad coils somewhere too, but no check engine light is on, and no codes present when I had the computer checked at an auto parts store. I think the dealer has a better way of checking though...Thanks!

 

Check engine light never came on. I am not a mechanic, but there are many types of readers. Some only provide limited diagnostic capability.

 

Thanks for the info. I have an 02 F150 4.6 speed, so your input has been very helpful.

 

The answer to this kind of issue has been posted here many times.
Coils develope shorted turns from heat ageing and cause missfire under light throttle loading in OD at speeds between 45 and 60 mph.
These coils will even cause a minor hesitation flutter off ide from a stop but then goes away depending on if the engine heat is acting on them at that moment.
This condition is not a 'hard' fault so won't set a code or lamp you can see..

 

I've got almost 180K on my 2000. I've replaced 3 or 4 coils so far. What I noticed was this - take a sparkplug and connect it to the end of a new coil. Notice how the friction keeps it together. (of course, if you shake it a little bit, it will fall off, but at least it stayed on) Now, my old coils that dumped a code & triggered a Check Engine Light, a sparkplug wouldn't stay connected to it - as if the spring on the bottom of the coil was too big or something. I believe the springs are what is expanding/contracting with the heat (in addition to the electric windings of the coils themselves) and this is causing a problem. NAPA parts sells the springs & boots as a kit. But I will be ordering acomplete set of coils on ebay or something & just change them out all at the same time just to eliminate any future problems for a while.

 

I'm not getting any codes, which is very frustrating! However, I think it is a COP (coil on plug) problem, and also agree that it's probably an issue with the springs/boots. I checked all of my old coils with an ohm meter and they seemed to be ok since none of them deviated very much at all from the others in resistance. I also checked three bran new COP's and noticed that the springs on them seemed much tighter than my old ones. If you're going to replace the coils (like I am considering) I would at least take a look at the following link. I'm not sure how good they are (having never bought anything from this company yet), but they're cheaper than anything I've found anywhere else to date. If this part doesn't fit you're truck, I'll bet that have the ones that do.

2002 Ford F-150 Ignition Coil IGN1319067X30359 | GenesisAutoParts.com

 

Bluegrass7: This issue occurrs in all gears, under light of heavy throttle. However, it does go away as the RPM's increase with speed through the gear. I have a 5 speed manual.

 

I have a 2003 F150 with 160k doing the same thing. It usually does in the worst while in OD at lower RPM's with light acceleration (not enough to kick down out of OD) I figured it might be a COP but didn't have any codes. So I started off by changing the fuel filer (didn't help), then I changed the plugs since it was about time anyway (didn't help). So now I'm back to the COP's but I hated to just start changing them out without knowing which one. The plugs all looked about the same, a little white but not worn too bad. All the boots on the COP's looked pretty good as we changed the plugs. Is there a way to tell which one is bad without getting a code? Or would you buy one or two new ones and just change them one or two at a time until finding the bad one. Any ideas would be appreciated.

 

I also have a 2003 and last year my truck was doing exactly what you are describing. And it was the coil. then a few months later it was doing it again, another coil. So i went ahead and replaced all the coils and havent had any problems since.

 

I don't see why you couldn't buy a couple and start swapping them out, but what a pain in the butt! I'm gonna bight the bullet and replace them all at once and be done with it. I found them for $20 a piece online. It's never fun dropping that kind of money, but it's better than fixing this only to have it come up again in a few months or a year.

 

Here is more background info.
The coil in fault cannot be picked out with an ohm-meter test because it is not a hard failure that 'would' set a code. If it was a hard failure, there would be no mistery about it.
Replacing coils is about a 70-30 deal and some luck.
What if a new or substitute coil had the same fault? You get confused and think it's not a coil when it still is with the same miss condition.
Changing them all could result in the same situation as well.
So you take a certain amount of chance / luck doing it in any manner.
Finding which one is either by sub or by a dealer stress test to pick out the coils that are low in output.
When a dealer does it, the coil is under their warrenty. When you get them, you get what you get for results and difficult to prove within a reasonable time frame for a warrenty return.
Reason why a low output coil will cause a light load miss is as follows.
Under OD conditions in the 45 to 60 mph range, the EGR is called to open. This causes the fuel injection to be reduced, exhaust gas routed back into the intake air stream and ignition timing to be advanced.
The result of all this is a very lean mixture in the 20 to 1 range +/-.
Under these conditions the voltage from all the coils has to be high enough to fire this lean mix. It one coil is low, you feel a bucking.
When you add enough throttle, the EGR system is exitied and mixture returns richer again and the faulty coil now has enough output to fire the mix, miss goes away until the next time you put the motor under the same driving conditions and it starts all over again..
The PCM keeps track of this for just so long without setting a code unless a software thresh-hold has been exceeded.
It you add or take enough throttle such that the fault is no longer present, the PCM memory cancells the history for that cylinder "for reporting the fault' and it starts all over again, hence no code is set.
.
This is type of fault in not very well understood because of all the configurations that are set up during that driving condition..
Looking at just a part of it and clearing the fault is pure luck most of the time.
Print this out and keep/ save and take to your shop when you need it to help clear this kind of fault.

 

Thanks for such a detailed explanation. It's makes a lot more sense now. Since this is a real common problem it would be nice if this could be posted in a permanent link.