Getting lean codes on both banks. My pcm is tuned for 58# fuel pressure, my avalanche engine is one of a few that runs on 50# from the factory. I have found no way to increase fuel pressure { no fpr that holds 58# will fit my rail }. I have tried everything else that will throw lean codes and found nothing. I drove the avalanche with no codes before I did the conversion.

 

If the fuel tables are not correct in the tune it could cause lean codes. If its setup for 58 and your running 50 then its going to be lean. Why not get the tune fixed?

 

Did not know if the tune would cause it, that's why I was asking.

 

A wrong tune could.