What are you talking guys?
lambda reads airflow? lol
When the MAF is deactivated you run in secondary load mode = Throttle + MAP! When the engine is in idle the load 100% is calculated via throttle and in software there are many maps for airflow calculation in function of Throttle angle, throttle size, engine displacement!
Installing bigger throttle will kill your airflow calculation if you miss to recalibrate all the Throttle air flow model in the ECU and you will face too lean AFRs and too high positive fueltrims!
I do for many years MAFless setups when the turbo inlet is bigger than 80mm like PTE 6262 or 6765 in 20VTs with injectors ID1000 or ID1200 without having any issue with fueltrims, idle and fueling at all.... Of course for finetuning are needed maaaany files and hours, if you are looking for the perfection which for me is the most important.
KRKTE: I have posted a calculator .xls in NEFMOTO forum
TVUB (easy to be found over the internet for DEKAs and IDs)
FKKVS (The most important and smartest map in Motronics)
TEMIN: 0.5ms is fine for 870cc @ 3bar
cheers,
Fotis