How to test Injector Failure?

[Trekman]

Service engine light came on and engine runs rough. Pulled codes and came up with P1274, P1119, P0605. The last two are probably due to my Western Diesel tow chip, but the P1274 is cylinder 4 being out. Pulled the valve cover expecting to see the wire harness loose, but it is clipped tight. Started motor and injector #4 is not exhausting any oil, so code is correct.

Pulled the connector on the injector #4 and hooked up volt meter and reads 3DC volt or 7.5 AC with engine running

Does this mean the electric is fine and the injector solenoid is bad?

How do I test the solenoid?
What should the voltage be at the injector?

Is there anything else I should check?
Should I do an OHM test on the valve cover gasket connector?

The injector wire harness was replaced about two years ago and still looks new.
Could the Valve cover wire connector be bad and still read voltage at the connector?

Thanks

[ridiculously_necessary]

buzz test will test the solenoid. i know AE will do it, there are a few other scanners as well. typical OBDII wil not. I forget, does a wire go to the injector or is it plug itsself in to a socked when install? wonder if a wire came loose?

if not the solenoid or harness then it sounds like a failing injector.

[Trekman]

I tested the wire harness from the IDM to the Injector #4 and it has good continuity on both sides. Also checked the resistance on each Drivers side Injector coil from the IDM and they all read 3.3 ohms. No shorts to ground

I swapped the Injector Coils between #2 & #4 and the problem remains on #4.

With the wires having good continuity-does this mean the IDM must be the problem?
Could the Injector itself be the problem?

The truck has 170,000 miles on it

I do not have a scanner or buzz tester. The codes were pulled by a local shop for me

[ELT]

The wiring plug can get loose on the injector and cause low voltage. You may need to drop in a reman injector.

[Trekman]

It cannot be the plug at the injector since I swapped the injector coils between #2 & #4 and the problem stayed on #4
The connector is part of the coil, so if that was the problem it would have moved to #2

So it seems like I have isolated it down to the Injector or the IDM. How can I determine which one it is?

[ELT]

The plug in the harness that goes onto the injector kind of wallows out and gets slightly loose where it plugs onto the injector. This makes a poor conection and low voltage to the injector. If this is a problem the power is not even getting to the coils you swapped. My local ford dealer told me this in my search for a low cylinder contribution on cyl. 8 on one of my trucks.

[mcbadwish]

Swap the injectors and see if it follows