I need some info please when testing the ficm key on engine off 48.5 volts .
will the voltage increase when the engine warms up?

 

It shouldn't increase much if any, 48 volts is spot on. The FICM volts need to be greater than 45 at all times from KOEO, cranking, idle and WOT.

 

Mine will vary slightly when running my Dashboss testing. It will move from 48.0 to 48.5 to 49.0, and back again. Never seen it below 48.0.

 

Thanks I am having problems when the truck sits all night the next morning it misses and rattles but when it warms up it runs like a champ I just change the oil and filters and added RevX got about 100 miles on it hope that it works
I tested the Ficm this morning ad the voltage wa about 49 Koeo and also with it running

 

Voltage KOEO, Cranking and running need to be 48v, the colder it is outside the better the test. If your FICMholds 48v below freezing it's perfect.

If you pass that, i'd say your suffering from some injector stiction, could take a bit more than 100 miles to work itself into your injectors and clean em up

 

Symptoms of the 6.0 Common Cold.

Rx;
2 bottles of Rev-X
5w-40 Synthetic Oil
and hope for the best as injector stiction is common to the 6.0

 

Check this you tube video on how to help eliminate that stiction which causes that cold start roughness.