I have a 2018 3.5L Ecoboost with P21D2 and P0304 codes. I know the following:

P21D2 - Cylinder 4 Injector B circuit / open
P0304 - Misfire on Cylinder 4

So I know I am looking at cylinder 4. I plan on doing a complete check of the plugs (changed a few months ago truck has 102k on it), coils and injectors and harnesses. What i am trying to figure out is which injector set is identified as the "B" injectors? Interestingly enough Im not seeing any conclusive information on which is which, even after searching the internet for hours. The closest I got was a mention that it may be the high presure injectors that i assume are on the top. I am competent enough to do this service myself as long as i know which i am replacing. Can some of you fine people pont me in the correct direction?

Thank You

 

Injector B would be the high pressure.
No need to do anything else unless you want to.
The 304 code will go away when the Injector issue is fixed. It's a natural reaction to the Injector failure because the program Blends the use of both, depending on conditions.
The 30x codes are set because the Crank sensor measures Crank rotation time that if too Slow, sets the code from lack of Combustion pressure above the expected min level in program.
Good luck..

 

Ok great thanks for the reply. Just to be clear the High pressure injectors are the PFI or the DI injectors?

 

DI direct injection, hi pressure, into the cylinder, a closed space
port injection PI, low pressure in the intake port and carried in with the airflow.
.
Low pressure fuel from the tank feeds the high pressure pump to raise the pressure.
On the top of the engine you see a short hose from the low rail to the HP pump.
Good luck.

 

You are the man. Much appreciated.