CM2350 derate 6255 only no fault codes

[greg1227]

Thanks for the response
It is not de mandated all factory . We had replaced exhaust sensor recently ( month or so ) with a Cummins sensor . We have the latest ECM update from a friend with a factory Cummins computer . We did see oil in the valve cover connector so that will be something we will deal with . Did not do rail test will do that as well . We ohmd the wiring from ecm to connector at valve cover all exactly the same and wiggled wires during test . Will address all of your concerns on Monday when i get back to shop . Still wondering why it would show a single count for the misfire fault and then show derate in 30 minutes . Now no code except derate code and instantly when doin a injector performance test . Will do all testing Monday and get back thanks again