The LS1 in my Monte Carlo started misfiring and running rich only in bank two all of a sudden one day and I can’t figure out why, I’ve swapped injectors, coilpacks and plugs from side to side and it didn’t follow so I can rule those out, it also has good compression in every cylinder and all of the wiring looks okay

car has never had o2’s and has driven fine for a year so isn’t that either

is it possible the ecu took a ****? There’s nothing else I can think of

 

There's a forum for this kind of question..Tuning/diagnostics.

https://ls1tech.com/forums/pcm-diagnostics-tuning-7/

 

Posted there