- Jul 6, 2014
- 9,265
Hey guys, as you remember I had the issue with the tune on the sierra and basically bought a pcm from a junker. Scan numbers and everything correct and it's from a 2500hd. But ever since that swap the truck hasn't been... how do I put it... the same. Power is down, fuel economy dropped by about 1 mpg and shift points don't seem right. I had the scanner on it and one of the upstream o2 sensors is more of a box wave then a sine wave. Being the originals with about 160k on them would it be a safe bet that it could cause the loss of fuel economy? Motor mounts also seem to be on their way out...
6.0l vortec
6.0l vortec