Hey guys I'm kinda new here so pardon if i dont do this right. I have a 2001 duramax .Truck has never been to the dealer until FPRV went out in october . when truck was done it idled like a dream, but i lost 3-4 good mpg. and some good power from a dead stop. power now comes on a little later, say after 2000 rpm. went to dealer they said tech may have reflashed to update computer. then he proceeded to tell me that he couldnt go backwards . Is this just a gm requirement or what ?? I have read some where else that there are several flashes available from gm for the truck. but cant find any info on it.
Can anyone:eek: help??

Once a update is installed using a oem software update there is no way to reverse it, the old calibrations are locked as a new one is released/installed.

can i purchase new ecm with the original program, or can my old ecm be completely reprogrammed ??

You can get your ECM reprogrammed at Westers Garage, check there website. I have had mine done for 5 years now and I am very happy with it.

Hey , thanks for your input , i 'll check them out.