I have a 03 F250 with 5.4. Yesterday it seemed to be missing like a sparkplug wasnt firing. Shaking pretty bad when under a load, when excelerating on the highway ocassionaly in the middle of the shakes it pickes up and goes. About 2 months ago i had FORD replace the #5 plug and coil that went bad. Its showing the same signs now. I went around while the engin was running unpluging each coil seperately to see if the engin stayed at the same tone while unhooked. I thought this would narrow it down. After all 8, each one i unhooked the engin died down a little. Which means in theory all 8 plugs are fireing. So now im left with fuel injectors. Can anyone help??? Its driving me nuts...

 

Sounds like your coil test was done when it was working. You have to do it when its skipping...If it did work then your inj is working also. Its not suggested to play with connectors with the engine running although I've never heard of anyone breaking anything. Sounds like a coil for sure.

 

Yeah im sure its not to smart, but it was the only thing i could think of short of 80 bucks for FORD to test it for me. Everything seemed to work afterwards. If a coil goes bad though how would it work sometimes and not others? I figured once it wend bad it was done for.

 

I've never had any problems with any of my 3 modular motors and coils but IF I did I'd do the following:

Inspect the electrical connectors that plug into the coils. Clean them with electronic solvent, dry them and put a dab of dielectric grease in the plug.

Take each coil out and look for signs of water or coolant having filled the spark plug cavity. That will short out a COP and destroy it over time.

While you have the coils out, look at the boot leading to the spark plug. Check for signs of arcing to ground. The boot may be torn or have holes or burn marks in it. If so, replace the boot.

Use an ohm-meter on each coil to determine the resistance. They should be between 0.5 Ohm and 1.5 Ohm. All 8 on my 2003 are at 0.8 Ohm. If they are outside thoses specs, then the coil is most likely defective. Maybe you got a marginal replacement coil.

Having found no problems, I would then take out and inspect each spark plugs to see if they are dirty or the electrode is rounded or worn out, or the gap is larger than .054". That being the case, I'd put new spark plugs all around and gap them, tighten them at 13 ft/lbs. If not, put them back at 13 ft/lbs.

When putting the coils back on, put dielectric grease on the spring that contacts the spark plug so that you won't get corrosion and a bad connection.

ON EDIT: Blow out the spark plug cavity before you take out the spark plugs. There always tons of crap in there when I take the coils out.

 

Moisture around the plug boot is very tempermental. Did it just rain in your area?
If it dries up it'al run better. esp if boots are cracked.

Dick

On edit Ya what he said.. LOL

 

Thanks for your help. I was afraid to even look under the hood of my new truck. I have worked on engins b4 but all those coils and STUFF on top overwelmed me. After i got in to er it doesnt seem to bad. Im goin to start at the top of your list. lol hopefully its the rain like you said and its just the weather. Thanks again for your help.

 

No luck yet. Each coil read 1.3 Ohms. Im going to check the plugs this weekend. Is it possible its fuel related?

 

It could be, who knows. In that case, you can check the electrical connectors on the injectors for dirt too and clean them/put dielectric grease on them. What about the fuel filter, how long ago was it replaced? (I replace mine once a year.)

 

WEEELLLLLLLL. I have had the truck for about 4 months. Havent changed it yet. I bet its due. It just doesnt seam like the filter could be the case. I think ill go ahead and change it. Couldn't hurt. Will see if either that or cleaning the connectors does the trick. The thing that gets me is that the check engin light hasn't came on yet.

 

Takes quite awhile for it to come on for a miss.

 

Something else I just remembered. Last year, my boss asked me why his truck was missing really bad. We took a test drive and it felt like the truck was cutting out or missing really badly. We replaced the fuel filter, spark plugs, checked the coils but it still did it. Finally, we got a break: the check engine light came on. You wouldn't believe it but the IAC had a fault code. A short trip to Ford, the IAC replaced and the missing/cutting out was gone.

 

By the way things are goin now i wouldnt be supprised it thats it. Ill just keep on messing with the plugs and connectors and get that filter changed until that light pops on. Even when i had the truck running and unpluged the coil the light still didnt come on. I prolly need to clear it so that all 8 coils show a missfire if i do have to take it in. They might wonder how i drove it there. I dont know how the brain on it works though. Do i need to clear the memory so i get an acurate reading on the coad reader?

 

You need to have the condition for 3 driving cycles. Unplugging it just once or twice won't log anything. Here's what Ford considers a driving cycle from their books:

Idle vehicle for 15 seconds. Drive at 64 Km/h (40 MPH) until ECT is at least 76.7°C (170° F).

Cruise at 64 Km/h (40 MPH) for up to 4 minutes.

Cruise at 72 to 104 Km/h (45 to 65 MPH) for 10 minutes (avoid sharp turns and hills) Note, to initiate the monitor: TP MODE should =PT, EVAPDC must be >75%, and FLI must be between 15 and 85%

Drive in stop and go traffic conditions. Include five different constant cruise speeds, ranging from 40 to 72 Km/h (25 to 45 MPH) over a 10 minute period.

From a stop, accelerate to 72 Km/h (45 MPH) at 1/2 to 3/4 throttle. Repeat 3 times.

Bring the vehicle to a stop. Idle with transmission in drive (neutral for M/T) for 2 minutes.

For M/T, accelerate from 0 to 80 Km/h (o to 50 MPH), continue to step 11. For A/T, from a stop and in overdrive, moderately accelerate to 80 Km/h (50 MPH) and cruise for at least 15 seconds. Stop vehicle and repeat without overdrive to 64 Km/h (40 MPH) cruising for at least 30 seconds. While at 64 Km/h (40 MPH) , activate overdrive and accelerate to 80 Km/h (50 MPH) and cruise for at least 15 seconds. Stop for at least 20 seconds and repeat step 10 five times.

From a stop, accelerate to 104 Km/h (65 MPH). Decelerate at closed throttle until 64 Km/h (40 MPH) (no brakes). Repeat this 3 times.

 

This thread is exactly what I was "lurking" to find.

I have a 97 Ford Expedition w 200,000 miles. No leaks, no oil burning. The best running truck I've ever owned. Last year about March m,y truck started missing, so I figure it's got 150,000 miles so I'll have the plugs replaced. More power, but still got a miss under acceleration or going up a hill. So I take it back to the Ford dealership, and they tell me # 2 and #6 coils need to be replaced. I replace them both and the problem occurs almost as soon as I drive off the lot. I take it back, and they tell me #6 is not working properly and to bring it back and they would replace it. I scheduled an apppointment for 1 week later, but the missing stopped in the meantime. After a few months it started missing again, only to stop missing the next day. 1 YEAR PASSES, and finally it misses so bad the check engine light comes on....but before I can get it to the dealership Monday morning the light goes off. Ford dealership hooks it up and runs diagnostics and finds nothing wrong. So we test drive and sure enough truck begins to miss. So dealership recommends I do a 30,000 mile maintenance and replace air filters, fuel filters, clean injectors, flush transmission etc. I get it done, and the dang thing is still missing. ANY SUGGESTIONS PLEASE...THIS IS DRIVING MEW NUTS

Also, I read on this thread about an IAC...WHAT IS THAT.

Thanks, THE NATURAL

 

IAC=Idle Air Control. It's on the back of the throttle body. On an F150/Expedition, you'll have to take the "beauty cover" off to see it better. It faces the firewall and has a hose running from it and then to the air filter intake tubing right after where it attaches to the throttle body. (Don't confuse it with the EGR valve which had tubing coming from the exhaust manifold.) First, go to Autozone or someplace that can pull the codes once the check engine light is on. (Or you can pull "pending" codes even if the check engine light isn't on too.) Make sure the code relates to the IAC, in this case you should get a P0505. It's a simple replacement, just two bolts holding it on and the part only costs $54 at Napa.

If you get a P0301 through P0308, you still have an ignition problem, namely misfires. P0301 = cyl 1, P0302 = cyl #2 etc... If you get P0351 through P0358, you have a coil failure. P0301-P0308 don't necessarely mean the coil it at fault. My co-worker brough me his truck last week, and he had a really bad miss especially under acceleration. I pulled the codes and came up with a P0304 which is misfire on cylinder 4 (last cylinder near the firewall on the passenger side) I tested his coil (Got 1.10 Ohms which is good) I then pulled the spark plug and there was all kinds of rust on top where the coil spring makes electrical contact on it. I sanded the spark plug connector clean, put dielectric grease on the spring, put the spark plug and coil back on and the problem was gone.

It could also be a small vacuum leak either on the PCV hose or on the IAC hose so check these two hoses for small cracks. (but that's less likely)

THE SYNTHETIC