maybe you can answer my original question: why is this claimed as necessary when no one else (at
TheDieselGarage) doing a CR cummins swap has to do anything associated w/ the dealer?
I hope i didnt come off as saying its "necessary" . lets see if i can spew whats it my head without confusing it anything further.
the ecm is using a bunch of signals from various parts of the truck to alter injection timing, and rail pressure. if one eliminates those signals without changing the ecm accordingly the ecm will go into a pre-set fueling program . not the best, it will work, but you wont be getting what you paid for out of your programmer/tuner or engine.
IF the ecm is seeing all the signals it thinks its supposed to it goes into what is called closed loop . it will react in real time to mass airflow,manifold pressure's, tranny slippage ,egt, what ever its been programed to look for (not sure on the o3). closed loop is what you want if your going to leave an electronically controlled injector pump on. dont NEED it but you may want it.
a local diesel performance shop may even have the tools needed to alter the programing or another option may be something like a smarty
MADS Electronics - Smarty - CaTCHER - Smarty06
might be able to deal with the issues an deliver big power regardless of dtc's. you may want to contact them and see if they would be interested in helping you with a custom tune for the build. not unheard of if it showcases what they can do .
other than that the simplest way to do this kind of swap and make big power would be to p-pump it . this would take the ecm out of the fueling equation BUT also mean you would have break out the wrenches to turn the power up or down and you will want to go to a set of aftermarket gauges to properly monitor the engine.
My only reason for retaining a stock ecm is for the poops ang giggles of being able to push a button on the fly and get milage or push another button and get big coal rolling power. that and it will make a good show piece for what im working on as far as the newer 6.7 cummins.
sorry for the book just spilling the brain. may not all be 100% accurate but i hope it helps .
In the end id work backwards, ie: dont care about changing power levels on demand ? not to worried about maximizing mileage ? or wringing every drop of power out of that mill ? then p-pump it and let the coal roll.
want to play with power levels and see just how many miles per gallon you can get then work towards an ecm controlled pump/injectors and closed loop.