6.8 V10 misfire

[tempobernese]

I have a 2000 F250 6.8 V10 with a misfire on cyl. #3. We have changed the spark plugs,coil,and fuel injector on that cyl. We have also checked the compression and it is 150psi. No codes are listed, the check engine light has never been on. All of the fuel delivery info looks good on the scan tool. Also there are no vacuum leaks. Any other suggestions???? Thanks, Dave

[rhandwor]

Did you install new rubber o-rings on the injector. Spray around the injector base and check for a leak. The engine will smooth right out if you have a leak and the carb spray hits it. Use a noid light and check for power to the injector. If one of your noid lights fits check for power to the coil. A COP coil on plug tester works fine for this. The injector tester is also a big help. I have used a stethoscope and you can hear them.
I was helping a friend on a big block chevy with a misfire and when enriching the mixture it worked fine. He got a couple of small block injectors at the junk yard.
If all this checks out check the fuel pressure a bad regulator will lean out a couple of cylinders.
I think you have a bad electrical connection or a couple of injector wires mixed up if you replaced an intake gasket.

[rhandwor]

What did you find on this vehicle?

[JDFFMechanic]

Having the same issue on a '99 f350 6.8L V10. I have narrowed it down to the primary side of the ignition system and am trying to trace the wiring back. This occurred secondary to a motor replacement, but have not found any wire pinches, yet. Check at the wires going into the coil with a test light or noid light and see if you are getting power. If not, time to trace wires back to the PCM... That is if you get no spark from a known good coil...