missing and sputtering all the time

[derrad]

I have been having problems with my 2005 f250. Started about a month a go. Started to get a miss or sputter when driving at normal speeds. It got worse until the truck was not drivable. Brought it to my tech and he told me that i had a bad injector #7. Replaced that and drove the truck for 3 weeks and same problem came back. This time he says that the # 7 injector is bad again and the ficm had caused the problem. He told me that because one of my batteries was on its way out that it causes a spike in the system and shorts out the ficm. Any advice would be appreciated.

[dannyboy950]

I know I sound like a broken record but check the wires/plug is completely seated on that injector, check also the plug to the FICM. Low voltages will cause the FICM to not operate properly. Low voltage and voltage spike are oposits of each other.

The only way a low voltage condition can cause a spike is if a cell in a battery is dead and the alternator has to charge constantly, it can cause the volt regulator in the alt.to fry and cause an overcharge condition. This is caused by the alternator not the FICM.