i have a12.7 detriot in western star .people who owned truck before changed code. on ecm. any one know how to change ecm with out code. or have a pass word that will work to get in and i can make my own code. set now for 68 mph at 1450 rpm drops rpm to fast on hills.only gets about 5.,5 to 5.9 mph pulling vans gross about 77 to 80 i think it should be better. maybe im xpecting to much any thanks

You might be expecting to much from a WS......but to change ecm parameters, you have to have the Detroit 12.7 program loaded onto a laptop. That can cost you a few hundred bucks minimum. OR...you can stop at any Detriot diesel shop or Freightliner Dealership....pay the $254 and have the parameters checked and set to your likings. You could even get your ecm program updated.

You could also locate one of the many "Diesel Doctors" out there, and have them tweak your program. That generally cost's more........but you may or may not gain from it.

You should ask around about what people in the know would expect that mpg to be with your set up. Important to find out before you do anything, as the previous owner could have it set for best performance. 77 to 80 gross seems pretty heavy, especially if it is consistently that heavy. When thinking about your mpg, also don't forget to consider your speed. Of course consistently faster speeds will keep you from getting the best mpg, which I'm sure you already know.