Ford 5.4 engine miss

[Pops15]

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?

 

[mmurphy]

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.

 

[wedge40]

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

 

[Pops15]

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.

 

[Egon]

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!

 

[wedge40]

Pops, I'm not a mechanic, I don't even play one on TV , 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

 

[Diamondpilot]

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

 

[rjkobbeman]

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.

 

[Pops15]

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

 

[Diamondpilot]

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.

 

[dstig1]

I get a blank screen with the scanner. No reading whatsoever. Makes me wonder if its a computer problem.

First thing - check your fuses. The reader port is on the same fuse as the cig lighter. If that is blown, you will get nothing plugging in a reader as there is no power to the port. Ancient SD trick

Then keep a reader with you for when you have the problem crop up.

 

[kyspartan]

when was the last time the fuel pump was changed. i would get the pressure checked on it at least i have changed more fuel pumps than i would have liked, i have a 3rd gen camaro waiting for me to put pump in and there no worse car than those. gotta drop the rearend and exhaust just to get the tank out grrr . and dont worry about unhooking the battery to clear the codes, obd2 will keep the trouble codes even with a loss power unlike obd1 computers. they have to be cleared through a scanner. check the fuse for your port.

 

[sbohan]

THose coil on plugs are notorious for startin to die around 80-100K Anything past 100K is a bonus. I've seen some hit 200, but they're a commonly failing object due to heat and age. Get your scanner reading, or try another scanner; it should point you in the right direction. For what it's worth, there some newer cheaper ones out there now that can record. I think it's autox-ray and they've got one that will log it, so you hookup and drive around, then can download the info back to your PC. It also has some basic diagnostic tests. Worth the few hundred if you've got a obd2 vehicle you're going to maintain yourself.

 

[kebo]

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

A COP is exactly what I would suspect. I also have a 2000 F150 with the Triton 5.4L V8 engine, which has the COP packs on it. My first one went bad at about 60k, have since had about 3 others to go bad. At 170k, I think another one is intermittent now. It seems to misfire at times, but if I park it for a few hours it seems to clear up. Will just keep running it until something happens, hopefully if it's a COP it will give up and quit altogether and I'll be able to look at the diagnostics and tell which one it is. My experience is that the computer doesn't log a code UNTIL you see the check engine light is lit up. Then you should be able to read the code off of it and tell which COP is bad, if that indeed is the problem.

 

[Pops15]

Cig lighter works but still get a blank screen on the scanner. Scanner works fine on the car.

I can check fuel pressure but in my experience when an elec fuel pump is bad it just plain quits.

I haven't had time to check the coils. My Lincoln has 170K+ miles on it and has only had one coil replaced. Actually the coil was good but the boot was bad and the parts store was out of boots so I just bought a coil with a boot. That was probably 50K miles ago. I've also got a '95 Grand Marquis with low miles but lots of years on it. Still has original coils and runs great.
A Ford mechanic told me the boots start to go bad when the plug gap opens or the plugs are fouled.......and the coils go bad if the bad boots aren't replaced. As soon as I get time I'll test the coils. If they check out ok then I think the computer is the next logical thing to look at.

I'll post back with results.
Thanks for the help!
Pops

 

[Diamondpilot]

While the boots on COP can cause a problem the biggest issue is heat. I still think you have a coil breaking down when it gets hot. I would buy one more coil and start at the plug that is closest to a heat source. Try it for a few days then move it to the next plug if necessary. Usually the plug right by the exhaust manifold is the culprit.

I can not explain the scanner not working.

Chris

 

[sld]

Verify what fuse the diagnostic port is on and check the fuse.

Have you change the fuel filter? With a miss under load that is the first thing I would check.

Don't throw money at it until you can get a decent diagnosis. Misfires will almost always throw a code.

 

[Pops15]

Verify what fuse the diagnostic port is on and check the fuse.

Have you change the fuel filter? With a miss under load that is the first thing I would check.

Don't throw money at it until you can get a decent diagnosis. Misfires will almost always throw a code.

Changed the fuel filter.
10-4 on checking the fuse.

 

[dstig1]

Verify what fuse the diagnostic port is on and check the fuse.

Have you change the fuel filter? With a miss under load that is the first thing I would check.

Don't throw money at it until you can get a decent diagnosis. Misfires will almost always throw a code.

Actually the Ford COPs are notorious for going bad without throwing a code until they completely fail.

And yes, actually check the fuses, despite the cig lighter working. I don't know the fuse number on the earler SDs for this. It is also possible that your reader may not work on this SD. Trucks over 8500 lb GVWR are not required to meet OBD II computer standards, and I recall (dimly) hearing that early SDs (the line started in 99) were not totally compliant. High end readers should be compatible, but probably not all the basic ones.

 

[kebo]

Pops15, can you tell me where the fuel filter is located at on the F150's?? Extended cab models, if that makes any difference. Thanks.