I have a 2001 F150 with a 5.4. 55,000 miles. It was running well before I changed the spark plugs today. I installed the Motorcraft platinum gapped at .054. After I finished I took it for a drive and it ran fine until it warmed up. Then it developed a miss and a bad hesitation. I checked all coil and fuel injector connections, also searched for vacuum leaks, everything was fine. I then removed each coil and injector connector one at a time with the truck running. The idle got rough each time so I presume the coils and injectors are working correctly. While it was idleing the check engine light came on. Does anyone have any ideas? I am taking it to Autozone in the morning to see if they can scan it. Does anyone know where the OBD connector is on the truck? I have changed plugs at least a hundred times in my time and this is the first time I have ever had a problem, your help would be appreciated.

 

The connector is under the dash on the driver's side, to the left of the transmission hump. Get those codes from Autozone and we'll go from there.

 

Clear the codes and run it again.
You may have caused code by unplugging things while the engine was running.
Sure the plug boots are seated on right?

 

 

Very hard to even guess at this point, but I do not remember reading that you pulled the plugs back out and inspected them. Might be worth a try. If one of them was cracked...possibly from shipping and handling or installation, or possibly just quality control, the crack would only get worse as the engine warms up. Heat equals expansion in just about any material. Be sure to let us know what those codes read.

 

Waiting for Autozone to open. I checked the plugs, they are all fine. I also made sure that all the cop's were seated correctly when reinstalled, they are. I will post the code/codes as soon as I get them. I used diaelectric grease on the boots and anti-seize on the cop holddown bolts. I thought I did everything correctly but it would be quite a coincidence to have something unrelated show up at this time.

 

I had the scan done. It showed three codes. po307, po304 and po113. For pl307 and po304 I will take the coil off test it, remove the plug and reinstall. What do I do for po113?

 

P0113 is an IAT code I think, high input. Fix your misfires first and worry about that one afterwards. Of course though, make sure you hooked the sensor back up.

 

motorcraft plugs, well theres your problem right there. its my understanding autolite makes ford plugs pure junk IMO.

 

I think you're confused. Motorcrafts or Autolites are usually the best bet for plugs in these motors; everything else is hit and miss, in some they work great, in others they don't. The greatest chance for success is using Motorcrafts or Autolites.

 

Forget the plugs for now. There's probably nothing wrong with them.

I think that you should double check everything you removed. Make sure the IAT is plugged in correctly, and reset the codes. Then run the truck again and see what comes up. There's no telling what codes you threw by pulling injectors and coils off.

The IAT on my truck is located in the intake tube. It is a sensor that is stuck in the intake pipe. It has a wire that plugs into it. It is not the cause of your missfire. (IMHO)

P.S. My owner's manual recommends replacing the spark plugs at 100,000 miles. (I think) It's a good idea to stick to what the service manual says until you have a problem.

 

OK, I swapped the 4 and 7 coils with 1 and 2. I still have the bad miss and hesitation but after a 10 mile drive the service engine light did not come on. So, do I start at the simple stuff and change the fuel filter? I have tested each coil for resistance, primary and secondary, I have looked at each spark plug, I have checked each injector connection. There are no vacuum leaks. What else could it be? Does the dealer have a way to diagnose without check engine codes? I would hate to spend a fortune on diagnosis.

 

It's not your fuel filter, or air filter, so don't bother. Check the #4 and #7 spark plugs. If they look fine, then ride it around until a light comes on. I think there's a way to check pending codes but I don't know how. Maybe somebody will chime in.....

 

Autolite is owned by Allied Signal,which is owned by Honeywell.Motorcraft and Autolite plugs are made in the same factory,but,Motorcraft plugs are made to strict Ford specs.How do I know this? I e-mailed Autolite and they e-mailed me back that response.

 

not confused at all, and i dont care who owns who frankly. ive had problems with these plugs in every ford ive owned from cracked insulations to bad misfires that couldnt be explained, solved only by changing them.