Hi! I have a 2003 ford f250 4x4 with a 5.4 and a 6 spd manual tranny. My truck has 68,000 miles on it. Around 65,000 I changed my spark plugs. After that, my truck made a 1,300 mile trip hauling a 38' trailer with no problems. Now, three weeks later, my truck has a random sputter or miss fire under load (most easily detected when the engine is around 1000 rpm and you push on the go pedal). I have no check engine lights. So far, I have replaced the fuel filter and the spark plug boots/wires. I also replaced two coils that seemed suspcious, but none of this made any difference. Also, the oil and antifreeze look good and don't smell suspicous of a blown head gasket.

Any advice???

Please help me b/c I am lost right now...

Also, may I ask what the qualifications are for the check engine light to come on with a cylinder misfire? I can make it miss, sputter, and carry on for over 30 seconds continuously but still no light. Not real sure what's going on. Thanks for your time!
Robert

 

Clean the Mass air flow sensor. Also clean the throttle body. If neither one of those work, check the coils. From what I understand usually the #4 coil goes bad (not sure why though) Or do what I did and replace all the coils. I haven't had any issues since.

 

can you please tell me how the cylinders are numbered on the 5.4? The two coils that I replaced where the back two. One had what appeared to be moisture @ the coil pack under the boot, and the other had some slight corrosion on the posts of the plug. All the plugs on the wiring harness look great though. I'll get a can of MAF/Throttle body cleaner and see what that does.
Thanks!

Keep the advice coming!!!!

 

If I'm not mistaken it's the rear passenger side. You could have another bad coil, or moisture inside the coil boots on other plugs.

 

I replaced all 8 boots and then the rear coil on the driver and passenger bank today. Only one of the coil packs/boots had any moisture that I could tell and it was the rear drivers side (which I hence replaced). The rear on the passenger side had just the slightest amount of corrosion on the prongs where it plugs into the wire harness. I just sprayed about 1/3 of a can of throttle body cleaner in the the throttle body/ intake plenum and drove the truck home from the parts store (about 8 miles, 15-20 min) and it didn't help at all. I made it missfire/sputter for 5 solid miles, varying speed from 35 mph to 60 mph by riding the brakes and I still didn't get a CEL. Right now, my MAF sensor is drying out in the house after a heavy spray down so I'll have to let you know later if that helped.
Thanks so far!!! Once again, keep the help coming!
thanks,
Robert

 

bump for some more advice!

 

okay, update here on progress. So far I have:
1. put in new spark plugs about 3500 miles ago (about 3000 mile before symptoms)
2. put in all new coil packs/plug boots two days ago
3. clean MAF
4. Cleaned IAC
5. Changed fuel filter
6. checked ohms on injectors (all around 13.2 ohms, between 11 and 14 is normal)
7. ran the tank as empty as I could (maybe two gallon left in the tank) and filled up with mid grade and techron fuel system cleaner.
8. replaced Cranshaft Positioning Senson
9. Checked TPS
10. Tried to check Cam Positioning Sensor (can anyone tell me the proper way to check it?)
11. had pending codes checked - random missfires detected
12. finally got a cel - random missfires detected

To re-cap it's a 2003 ford 250 w/ a 5.4 and 6 sp manual with 68,500 miles. When truck is lugged or if I floor it the engine misses. If you ease into the pedal, doesn't seem to do it, or if it does, isn't much. Also I can run the truck up to 4 grand (empty or pulling a trailer) without noticing a missfire if I don't just floor it so I don't think that it's a fuel supply problem (except for possible dirty injector).

The biggest improvement seemed to happen after I put in the new mid-grade gas w/ the injector cleaner.

We are trying to farm (keeps trying to rain) and my car is broke so I have nothing else to drive to work or to use to farm/haul grain so I need to get this thing fixed. Any advice is appreciated.
Thanks,
Robert

 

I'm goin through the same thing now. 2003 F250 with the V-10 engine. Did the plugs two weeks ago and it ran great for 1 week. Then same thing started goin on again. If I stop at a stop sign or light, it dies at idle. I'm so pissed right now with this truck. I had the truck hooked up to a computer today and no codes came up. Running with a bad miss to the point that the truck almost bucks and no CEL. I'm gonna try replacing the PCV and hose and then the IAC. I'm lost

 

sounds like an IAC..

 

I agree that your's sounds more like a IAC (you can take it off and clean all the gunk out of it). But mine will start and idle fine, except for one day out of the last two weeks but the miss went away after about a minute of run time. Even when the truck warms up, the idle seems fine with no stalling when I push in the clutch or when I stop, ect. PLEASE HELP ME!!!

I am starting to think that I might need a reflash, but the truck doesn't even have 70,000 miles so nothing should be out of spec that should through the computer off...... Just frustrated.
Thanks,
Robert

 

I feel your frustration and went through everything you did and then some. Check your fuel evoporator purge solenoid valve. It should be located on the driver's side front fender at the end of the canister. Ford Only Part# F74Z-9F945-CA that is the number for my 2004 v-10. I've posted this numerous times to others but never heard a response as to whether it was the problem, so if it works please let me know.

 

did you put dielectric grease on all the high tension connections. I just went through my 05 focus with C.O.P.'s and cleaned the non combustion chamber side of the insulators, and smeared dielectric grease on everything, and picked up 6 mpg. it seemed to run fine before with no check engine light, and doesn't run any different now except it goes way further on a tank of fuel. had a 2000 focus washed the engine and it wouldn't even run til we pulled the plug wires and blew out the sparkplug wells. high humidity can be enough to cause partial high voltage shorting

 

What brand of plugs did you use? These modular engines seem to work best with the Motorcraft Platinum plugs. I have heard of other owners who have had misfires and sputters using other brands. Some owners say Autolite also works and a few have had decent luck with Champion.

As for the CEL, it about takes a dead cylinder to light a CEL. This is why a scanner that can read PENDING CODES is important. A misfire will set a pending code, but lighting a CEL seems to take an act of congress.

 

I have never heard of that before, but what would I be checking for? I am tackling the IAC this weekend and will attempt to clean it and reinstall.

 

Autolite Platinum. I took the advice of this forum and everyone said motorcraft or autolite. Sorry for hijacking the thread.I will start a new one with my issues.