Bluegrass7:

I drove my truck again today, and am experiencing this intermittent missing in gears 2,3,4, & 5 during acceleration. I also once again noted that the "Theft" light flashed on an off (at least once, and many times more than once) during each episode of missing. Your previous comments that I have read regarding this have always noted missing caused by the COP in OD, which I think means 5th gear on my manual transmission. Am I correct about OD being 5th gear on a manual, and is your explanation also true for others gears? Thanks for taking the time to help people like myself that are not as knowledgeable about this!<?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o></o>

 

Some of the other guys may be able to speak to this better than me. But a friend of mine works at a Ford Dealership (body shop painter), but he told me that the mechanic there advised him to be careful with the aftermarket COP's that they are not very reliable. He said they get alot of them in that were just changed that are failing again in a short period of time. For me based on that advice I ordered Motorcraft from Rock-Auto for around $50. If they will last another 160K I will be happy, but I don't want to be changing them again in another 20k if I can help it to save $25. I am just replacing them as they go bad. Not buying them all at once.

 

I haven't spoken about all the areas this type of miss can affect.
On a manuel or auto, the actual PCM actions to set up the driving conditions are controlled by a number of inputs to the PCM.
1. The road speed.
2. The throttle position.
3. Engine RPM.
4 A timing function.
This way the PCM can handle the function with nearly any transmission without actual reguard to the gear.
How it generaly goes:
When within a road speed range, RPM range, and throttle position, the PCM begins a short timer to see if these conditions are stable (mainly by driver action with the throttle).
If the timer times out, the EGR routine is called and all the actions follow.
If the throttle position is advanced causing a down shift and calling for more power, the PCM sees the advanced throttle position and exits the EGR routine back to normal engine conditions, to provide for that power request.
You can see from this that the type of transmission makes no real difference.
The coil fault is most always apparent in OD so the auto trans gets the nod but incorrectly. Only a minor point. It can happen in 3rd gear as well.
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5th gear in a manuel is usually an OD gearing depending on the make of transmission and the application.
For example a 6 speed manuel in a car could have at least 2 levels of OD. In a truck, it can be different.
Bottom line is a motor could be driven lightly in a lower gear and still call the EGR routine within narrower limits if all the items above are met and still missfire due to a faulity coil..
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Btw, something little known while driving in the 50 to 70 mph range is, if you let off the throttle quickly, the transmission lock-up comes "off" the RPM will increase about 300 rpm when some throttle is given again, then the trans will re-lock and the RPM drops again.
This action is for a different reason and also under a short timer if no other driving actions are detected. The brake application may also get in on the action.
The reason for this is in a panic braking situation, the PCM will unlock the converter so the motor won't add to the braking distance in a real emergency situation. This action has been in effect since at least 1984 and the first transmissions with electric converter lockup using PCM control.
Hint! one reason the trucks are so hard on front brake life. (no engine retard like old times).
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..As for your theift lamp flashing, it's a new one for me in relation to a missing condition.
As stated in a previous reply, the Thieft system is the PATS system that stands alone but has a "bus" to the PCM to exchange data that tells the PCM and the PATS that all the data matches so ok to allow the PCM to allow the engine to start by setting a 'BIT' in a software word address. If this bit is intermittant, it may be part of the issue.
I would be looking at the Dash for codes set and turning the ignition to RUN a few minutes without starting and see if the Thieft lamp flashes without starting the motor. This would be an indication the PATS detects a fault.
Trying to explain dash testing is best left to another post because I have to review it after a long time of not doing it and haveing to look up the code responses.
A good internet search will find the info if you want to try. Or some one here may have an easy reference to the info.
The PATS system has a number of versions and is quite complex so not a way to explain it very easy nor is it really needed here.

 

Sorry it has taken me so long to respond. I usually get an email when someone has responded to my post, but didn’t this last time. Anyway, I’ve been disgusted with not being able to get this fixed! Just to keep you up to date with my efforts. Since my last reply, I changed all the spark plug boots / springs and put a nice coat of dielectric grease before reassembly. Sadly, there has been no change in the stumbling problems.<?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o></o>
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I am not getting any codes thus far, but will keep looking for one. I will also get into the truck and turn the key to run and wait several minutes before starting to look for the theft light to flash. Since the issue occurs only during acceleration and in all gears (even 1st at times), doesn’t it sound more and more like a PATS problem to you. Can the dealer find out what the issue is if it’s with the PATS as part of the testing they will do for $89? If there’s anyone with PATS expertise that could give me some input, I would really appreciate it. <o></o>
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I purchased and installed (8) new coil on plugs and the problem is gone. I found and purchased mine on ebay for $90 total including shipping, and so far so good. They are much more at the Ford house, Autozone or Oreilly auto parts.

 

Good to hear you found the issue.
I bet you felt it more as a 'skip' than an outright miss.
Coils that have shorted turns that are not hard failures won't set a lamp and code, as you found out.
Good luck.

 

I have not herd this fix before on any forums, so I thought I would post it. My son's 99 Ford V6 F150 was misfiring and had poor gas milage. He replaced the spark plugs and plug wires, and it did not fix the problem. He took it into Corky's Auto Repair in Quartz Hill and paid $65 for a Diagnostic. They said that cylinder number 6 was the problem and that it needed a new Ignition Coil. My son bought a new ignition coil at AutoZone and it still had the problem. He took it back to Corky's for a free recheck, and they replaced the number 6 spark plug and it RUNS GREAT! The bad coil ruined the first new plug he put in. So, I would suggest putting new Plugs, Wires and Ignition Coil on the truck AT THE SAME TIME so the bad part doesn't ruin the new parts. Ignition coils are about half price ($35) on Ebay. Good luck to all.

 

Hey man, I have an 01 5.4 4x4, 136,000mi. Its done this about 3 times over the past year n a half, its been the coils every time. It hesitates in overdrive, bout 2 weeks later it runs like total crap. So I got on ebay and ordered 8 brand new ones for 100 bucks and had them put on and she's doin great.

 

Ford using multiple coils is obviously a bunch of baloney! It used to be engines had one coil and you hardly ever had to replace it! Swap my ride indeed!

 

My 2003 F150 4.6 had the same problem. It was the coils previous posters mentioned. The bad news is once the coils start to fail, they seem to continue. After 4 had failed, I had them all replaced and the problem disappeared. Several other owners I spoke with had similar stories. If you wait long enough, the check engine light comes on and the failure produces a code on the machine. You might as well bite the bullet and replace them all. It will save you a lot of labor cost or time doing it yourself.