As I'm tuning an Evo 7 using Tephra V7, I kept getting p0107 CEL, 'fuel trim low' always read 12.5. The car has a new set of ID1050x injectors & I thought that the issue must be injectors scaling/latencies related, AFR was a bit rich during cruise. So I kept adjusting both the latencies & scaling until it resulted to satisfactory idle & cruise AFR (around 14.7). But no matter what, I kept getting p0107 with fuel trim low always at 12.5! The car has a rear o2 sensor while the rear o2 simulator option is enabled by default in the rom, could that be the cause? Can this CEL be disabled via ECU periphery?

 

If the time is maxed, you need to adjust the ROM more. Should he shooting for +/-5% on the trim.

 

I'm aware of that, but as I mentioned the trim low percentage (at max) won't budge no matter how I adjust injector scaling!