Ford 5.4 engine miss

   / Ford 5.4 engine miss #1  

Pops15

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Ford 555 TLB, Caterpillar Motor Grader, Kubota L245, Ford LGT 125, FABTEK aerial platform
I've got a 2000 F250 5.4 that has an intermittent miss. Truck has about 110K on it. I've been chasing the problem for awhile. The thing is it will run fine for weeks at a time, then it will suddenly develop a miss and has very little power under acceleration. If I back off the gas it will smooth out some.
Truck has had recent plugs, boots, one coil, injector cleaner, replaced a few suspicious looking injectors, fuel filter, air filter. There doesn't seem to be any rhyme or reason as to when it will start running badly. Sometimes it will run rough for a day or two then run fine for several weeks. Sometimes it will run bad for weeks then suddenly run fine. I have a scanner but I don't get any reading. The scanner works fine on my '98 Lincoln. Am I looking at a computer problem? I figured if it was a computer problem it wouldn't run at all. Could it be one or more sensors? I cleaned the mass airflow sensor. Didn't make any difference. Any ideas?
 
   / Ford 5.4 engine miss #2  
When it acts up is it rough at idle? EGR valve sticking is a good one for that if it has one.
Check with a hand vac pump at idle to see if it stumbles as vaccum is put on it. If it does not change, it is probably stuck open. I have bought new plug wires before at an Irish name auto parts store that did not help problem, but found out it still was problem.
 
   / Ford 5.4 engine miss #3  
Not sure if you have coil on plug, but if so I would guess you have an intermittent "COP" going bad or a plug wire that is shorting out. New plug wires do go bad. At 110K, when the first COP went bad you should have changed them all. I would keep the scanner in the truck, possibly even hooked up and read what going on when it misses.

Wedge
 
   / Ford 5.4 engine miss
  • Thread Starter
#4  
Has new EGR valve. Found a bad boot on one coil. I replaced all of the boots on the coils. Also replaced one coil. At $40+ each I don't want to replace the other 7 coils if don't have to. How common is it for a COP to have an intermittent problem?

I get a blank screen with the scanner. No reading whatsoever. Makes me wonder if its a computer problem.
 
   / Ford 5.4 engine miss #5  
I get a blank screen with the scanner. No reading whatsoever. Makes me wonder if its a computer problem.

There in could lie the problem. It's an area where troubleshooting is much different than what we were used to and at times impossible without all the correct gear. The Times they have changed!:D
 
   / Ford 5.4 engine miss #6  
Pops, I'm not a mechanic, I don't even play one on TV :D, but I'm relaying what happened to me on two different vehicles.
I know you have a F250, but you may be able to get some answeres here.

F150online.

This where is where I learned about the COP's. I had two go bad at once. I think around 100K and just had them replace all 8 when they worked on it. Cha-Ching. If the scanner is blank that would worry me, you could have a short somewhere. The intermttent problems are the worse. Just break already would ya. Good luck.. Let us know what fixes it.

Wedge
 
   / Ford 5.4 engine miss #7  
Find a Ford guy at a garage. He will know the common issues and where to look. Usually the COP near the exhaust will go first. I think its on the #5 cylinder. They break down internally due to heat but check this with the guys who know. It would be worth another $40 to me to try it then if there is no change you can move it around to all the cylinders to see if it cures the issue.

The first thing I would try is a new fuel cap. They have the vent in them and go bad from time to time. Its a cheap try. My sister had a similar problem on a 97 Blazer and that was all it was.

Still does not explain the issue with the code scanner not working????
Chris
 
   / Ford 5.4 engine miss #8  
Not sure if you have coil on plug, but if so I would guess you have an intermittent "COP" going bad or a plug wire that is shorting out. New plug wires do go bad. At 110K, when the first COP went bad you should have changed them all. I would keep the scanner in the truck, possibly even hooked up and read what going on when it misses.

Wedge

Just replaced couple of mine on our Expy. Same symptoms. Ours just wasn't running that good. Could tell things weren't running right... but not missing "enough" to be obvious. No engine light so I coulnd't pick anything up on my scanning tool.

Ended up being one or two bad coils. Not totally dead, just missing every now and then. Ran like a dream when we got it back from the dealer. That is, until a little rubber hose broke on our EGR/DPFE broke. I was able to catch that one.
 
   / Ford 5.4 engine miss
  • Thread Starter
#9  
I have a buddy that works at a dealer. He ran the symptoms by a couple mechanics. They basically said throw parts at it until the problem is fixed. It's easy to spend others people's money.
I also unhooked the battery so the computer could reset. That didn't help.

It's my understanding that the COP's go bad when the boots get burned....and the boots get burned when the plugs need to be changed. All the boots were in good shape except for one. I replaced that coil as the spring/wire looked bad. I replaced all the boots at that time.

I unplugged one coil at a time thinking I could isolate a bad coil that way. Did the same with the injectors. I couldn't isolate the problem that way. It usually idles ok, but not always. The real issue is under acceleration. I'm beginning to think the problem is with the computer. I'll do some research and find out how to test the coils. I think it's a simple resistance test. If the coils check out ok then I guess that will narrow it down to the computer. I doubt that it's the gas cap. I thought that might be the problem as I had an issue with the gas cap on the Continental, so I ran the truck with the cap off. No change in performance.

Thanks for the help. I'll let you know what I find out.
Pops
 
   / Ford 5.4 engine miss #10  
Good luck, but I think you will need one new Cop. The reason is heat. Things break down under heat. I fought a similar issue with a 454 years ago in a boat and fiscally broke down and bought a new ignition system which cured all.
 
 
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