Short and long term fuel trim question

[markNtennessee]

what determines or controls the fuel trims and why is it I have a major difference between B1 and B2 LTFT. at idle B1 is 12.3 and B2 is 3.1 and at 2500 rpms B1 is 0 and B2 is still 3.1. I dont know how to read the fuel trims and i really dont know what could be causing the difference between the 2 banks.

 

[sngltrck1]

various things such as combustion difference between cylinders & banks, variance in injector flow, airflow into each cylinder, etc. can cause this.

Check the fuel pressure, MAF and EGR at least.

Better mechanics will chime in soon ...