So while out running some errands today all of a sudden my truck started acting like it had a miss. I limped it home and pulled the codes to find a P0602 - ECM fueling calibration error. I cleared the code reset the ecm to stock settings and started the truck up and it's still there. I reprogrammed the truck to lvl 6 started it back up and still no change. Is there a way to check if its VP or the ECM? Thanks in advance to the help everyone.

P0602 is a Smarty thing.

 

Now if the error code comes back while stock then you might want to read over the error code.

http://articles.mopar1973man.com/2nd-generation-24v-dodge-cummins/59-obdii-error-codes-cummins/203-p0602-ecm-fueling-calibration

Thanks Mike thats where I started with that info and returned everything to stock from the smarty but it was still there. I'm going to try and do a battery disconnect and reset to see if this changes anything.

Battery disconnect does nothing. All you need to do is turn your key OFF to reset the computers. Even time you turn the key ON the computers do a fresh reboot. This tells me the ECM does indeed have internal issues and should consider re-flashing the ECM with true stock software and seeing if that fixes it. If not the on-board flash PROM is damaged and not holding data properly.

Ok so I somehow managed to clear the code but the rpm's are still surging and the truck isn't feeling correct.

Fuel pressure? Miles on VP? Is it one cylinder or many?

Fuel pressure is 18 at idle and 16 at wot. VP has about 120k on it. I used a modis and shut off each cylinder and it changes but once returned to operating it doesn't fix the rough idle.