My truck started to act up about a month ago. It is an 02 F150 Supercrew 5.4 with about 110K miles on it. I was on my way to the lake and it started to miss under load on the hills. Unfortunately, I disconnected the battery and lost the codes so I can't say what the service engine light had in mind. In any event, I pulled a plug and determined that they needed to be replaced. Put 8 new Motorcraft plugs and boots in. Seemed to be fixed. I drove it out to the lake and back again without incident. A 350 mile round trip. Drove it around town without incident for another couple of weeks. Then, last week we took it out of town and it acted up again. Not as bad as the first time but missing again - idling rough and missing and shaking a bit under acceleration. It set codes again and I checked them out. 171 and 352. The first is too lean on bank one and 352 is bad coil on number 2. I assumed that the 171 might be the computer trying to adjust for the misfire. Bought a new coil from the dealer and put it in. Reset the codes. Now, no 171 but still getting 352 after a couple of short trips. Wondered if I got a defective coil, so I swapped one and two. The new coil was now in one and I got a code of 351 so it moved from two to one. I took the coil back to the dealer and they gave me a new one. I have now put it in and am back where I started with code 352 again. So, now I guess my next step is to examine the wiring harness that feeds number two as it is still telling me it is the coil but I don't think it is. Will check to see if there is voltage and if wiggling the plug affects it. Can trace the wires back a bit to see if there appears to be any damage.

Anyone have any other good ideas? Anyone know if the plugs for the harness connection to the coils is available for replacement?

Randy

 

Have you looked at your injectors. I had a problem a wile back similar to what you have and i found i had a defective injector. Also check for moister on the spark plug boots. Hope this helps.

 

I think I have likely determined the source of the problem. I bought the truck used and one thing it has but I have not used, is an aftermarket command start setup. I did not get the remote control for that with the truck and have not tried to get one.
I looked a bit closer at the wiring this morning as I have begun to assume that this must be the source of the problem. I now see that there is a wire from this command start system that is soldered onto one of the leads to coil #2 which is the one that keeps coming up in the codes. So, I am going to completely remove the command start system from the vehicle and am guessing that may well solve my problems.

Will post again to advise if I am right.

Randy

 

Problem solved. There was a wire from the command start setup running through the engine bay to the leads to #2 coil. The wire had drooped down onto the engine and the plastic melted off. That let it short out. Apparently, that fries the COP. I had to replace the #2 COP again and now the truck seems to be fine.

Randy

 

Yes I to have recently had this prob., 2003 F150 5.4L, but our truck only has 98K miles on it. Drove it to town and got in it to come home and started missing and such. I took mine to the local parts house and ran a scan for free and ours came back with the following (1) ignition system fault-spark plugs ignition wires, coil (2) Vacume leak, (3) injector fault, (4) High or low fuel preassure. I started with the fuel filter that was the cheapest way to start. No good there, so I guess the next step is what you done replace the coil pack and plug wire and plug wich incidently mine is #6 . If any one else can help solve my prob. I would greatly appreciate it.