7.3L injector problems
I'm a new member here, I've browsed a few of the threads and I found some great info in the past, thanks for all your help so far. I am having some injector problems and I was hoping for some info. My truck developed a hard shake at low rpm and cannot build speed when upshifting. Feels like I'm driving on grooved pavement. I've changed the fuel filter and checked the fuel pressure, and since I run home made biodiesel i emptied the tank and put pump diesel in for now. None of that seemed to make any difference so I bought the auto enginuity program today and ran a buzz test and a cylinder contribution test. Buzz test sounded like injector 7 is weak, but I have no experience. Contribution test indicated the following:
P0269 Cylinder 3 Injector Circuit Contribution / Balance Fault
P0281 Cylinder 7 Injector Circuit Contribution / Balance Fault
P0284 Cylinder 8 Injector Circuit Contribution / Balance Fault
I'm not sure I should go replacing injectors if the problem is elsewhere, 3 injectors at once sounds a little unusual to me. Could it be the FICM? If so how do I test that? I have a friend with the same truck and can swap a few parts if necessary to diagnose. Any ideas?