I have a 2000 f150 with a 4.2 v6 and started to miss went and had codes
pulled and it had a active #2 cylinder missfire so i replaced the coil pack
worked good for a day and came back again.checked and has same code
replaced spark plug.no help replaced the injector still will not go away.am
missing somthing here any suggestion will be a big help

 

Sounds like a bad plug wire.Change the wires.BTW,try to stay with factory Motorcraft parts.

 

Dont forget to use anti seize and dielectric grease on the plugs and wires.

 

this weekend i replaced all plugs and wires ran it down the road and started
missing again and check engine light came back on hooked up and scanned
codes came back with #2 missfire again for some reason this truck does not
want to be fixed is there a possibility that any of the wiring harness could have a problem and if there is how would you check it to be sure

 

The only other things I can think might be wrong are;
coil,which you say you have replaced.
cam position sensor
Other then that,i'm stumped.Have you tried going to the V6 forum and doing a search on this? You might have to break down and go to the dealer.

 

well you will never believe what i found on this after changing all these parts
spark plugs,wires,coil pack and injector i raised the hood at night while it was running and when it would start missing i noticed it was sparking around
that #2 wire now thats just my luck.on that brand new set of wires i took one of the old ones put it on and it aint missed at all

 

i have a 5.6 v8 but i had the same problem and i replaced just about every ignition component in my truck to try and fix it. finally i was fed up and sent it to my mechanic and there was a heater hose running over one of my plugs and it had a very slow leak which would cause it to misfire over time. that was tightened then it worked fine. well........... couple weeks later it was back and i did some research and i have performance wires and supposibly they don't seat as good as stock wires so i did what they suggested. filled the plug wire boot with dielectric grease and popped that sucker back on and wahlah no problem since